2012 Amateur Extra Class Question Pool

Front 1

When using a transceiver that displays the carrier frequency of phone signals, which of the following displayed frequencies represents the highest frequency at which a properly adjusted USB emission will be totally within the band?

Back 1

D. 3 kHz below the upper band edge

Front 2

When using a transceiver that displays the carrier frequency of phone signals, which of the following displayed frequencies represents the lowest frequency at which a properly adjusted LSB emission will be totally within the band?

Back 2

D. 3 kHz above the lower band edge

Front 3

With your transceiver displaying the carrier frequency of phone signals, you hear a DX station's CQ on 14.349 MHz USB. Is it legal to return the call using upper sideband on the same frequency?

Back 3

C. No, my sidebands will extend beyond the band edge

Front 4

With your transceiver displaying the carrier frequency of phone signals, you hear a DX station calling CQ on 3.601 MHz LSB. Is it legal to return the call using lower sideband on the same frequency?

Back 4

C. No, my sidebands will extend beyond the edge of the phone band segment

Front 5

What is the maximum power output permitted on the 60 meter band?

Back 5

C. 100 watts PEP effective radiated power relative to the gain of a half-wave dipole

Front 6

Which of the following describes the rules for operation on the 60 meter band?

Back 6

B. Operation is restricted to specific emission types and specific channels

Front 7

What is the only amateur band where transmission on specific channels rather than a range of frequencies is permitted?

Back 7

D. 60 meter band

Front 8

If a station in a message forwarding system inadvertently forwards a message that is in violation of FCC rules, who is primarily accountable for the rules violation?

Back 8

B. The control operator of the originating station

Front 9

What is the first action you should take if your digital message forwarding station inadvertently forwards a communication that violates FCC rules?

Back 9

A. Discontinue forwarding the communication as soon as you become aware of it

Front 10

If an amateur station is installed aboard a ship or aircraft, what condition must be met before the station is operated?

Back 10

A. Its operation must be approved by the master of the ship or the pilot in command of the aircraft

Front 11

What authorization or licensing is required when operating an amateur station aboard a US-registered vessel in international waters?

Back 11

B. Any FCC-issued amateur license or a reciprocal permit for an alien amateur licensee

Front 12

With your transceiver displaying the carrier frequency of CW signals, you hear a DX station's CQ on 3.500 MHz. Is it legal to return the call using CW on the same frequency?

Back 12

C. No, sidebands from the CW signal will be out of the band.

Front 13

Who must be in physical control of the station apparatus of an amateur station aboard any vessel or craft that is documented or registered in the United States?

Back 13

B. Any person holding an FCC-issued amateur license or who is authorized for alien reciprocal operation

Front 14

Which of the following constitutes a spurious emission?

Back 14

D. An emission outside its necessary bandwidth that can be reduced or eliminated without affecting the information transmitted

Front 15

Which of the following factors might cause the physical location of an amateur station apparatus or antenna structure to be restricted?

Back 15

D. The location is of environmental importance or significant in American history, architecture, or culture

Front 16

Within what distance must an amateur station protect an FCC monitoring facility from harmful interference?

Back 16

A. 1 mile

Front 17

What must be done before placing an amateur station within an officially designated wilderness area or wildlife preserve, or an area listed in the National Register of Historical Places?

Back 17

C. An Environmental Assessment must be submitted to the FCC

Front 18

What is the maximum bandwidth for a data emission on 60 meters?

Back 18

D. 2.8 kHz

Front 19

Which of the following additional rules apply if you are installing an amateur station antenna at a site at or near a public use airport?

Back 19

A. You may have to notify the Federal Aviation Administration and register it with the FCC as required by Part 17 of FCC rules

Front 20

Where must the carrier frequency of a CW signal be set to comply with FCC rules for 60 meter operation?

Back 20

B. At the center frequency of the channel

Front 21

What limitations may the FCC place on an amateur station if its signal causes interference to domestic broadcast reception, assuming that the receiver(s) involved are of good engineering design?

Back 21

D. The amateur station must avoid transmitting during certain hours on frequencies that cause the interference

Front 22

Which amateur stations may be operated in RACES?

Back 22

C. Any FCC-licensed amateur station certified by the responsible civil defense organization for the area served

Front 23

What frequencies are authorized to an amateur station participating in RACES?

Back 23

A. All amateur service frequencies authorized to the control operator

Front 24

What is the permitted mean power of any spurious emission relative to the mean power of the fundamental emission from a station transmitter or external RF amplifier installed after January 1, 2003, and transmitting on a frequency below 30 MHZ?

Back 24

A. At least 43 dB below

Front 25

What is the highest modulation index permitted at the highest modulation frequency for angle modulation?

Back 25

B. 1.0

Front 26

What is a remotely controlled station?

Back 26

D. A station controlled indirectly through a control link

Front 27

What is meant by automatic control of a station?

Back 27

A. The use of devices and procedures for control so that the control operator does not have to be present at a control point

Front 28

How do the control operator responsibilities of a station under automatic control differ from one under local control?

Back 28

B. Under automatic control the control operator is not required to be present at the control point

Front 29

When may an automatically controlled station retransmit third party communications?

Back 29

B. Only when transmitting RTTY or data emissions

Front 30

When may an automatically controlled station originate third party communications?

Back 30

A. Never

Front 31

Which of the following statements concerning remotely controlled amateur stations is true?

Back 31

C. A control operator must be present at the control point

Front 32

What is meant by local control?

Back 32

C. Direct manipulation of the transmitter by a control operator

Front 33

What is the maximum permissible duration of a remotely controlled station's transmissions if its control link malfunctions?

Back 33

B. 3 minutes

Front 34

Which of these frequencies are available for an automatically controlled repeater operating below 30 MHz?

Back 34

D. 29.500 - 29.700 MHz

Front 35

What types of amateur stations may automatically retransmit the radio signals of other amateur stations?

Back 35

B. Only auxiliary, repeater or space stations

Front 36

What is the definition of the term telemetry?

Back 36

A. One-way transmission of measurements at a distance from the measuring instrument

Front 37

What is the amateur satellite service?

Back 37

C. A radio communications service using amateur radio stations on satellites

Front 38

What is a telecommand station in the amateur satellite service?

Back 38

B. An amateur station that transmits communications to initiate, modify or terminate functions of a space station

Front 39

What is an Earth station in the amateur satellite service?

Back 39

A. An amateur station within 50 km of the Earth's surface intended for communications with amateur stations by means of objects in space

Front 40

What class of licensee is authorized to be the control operator of a space station?

Back 40

C. All classes

Front 41

Which of the following special provisions must a space station incorporate in order to comply with space station requirements?

Back 41

A. The space station must be capable of terminating transmissions by telecommand when directed by the FCC

Front 42

Which amateur service HF bands have frequencies authorized to space stations?

Back 42

A. Only 40m, 20m, 17m, 15m, 12m and 10m

Front 43

Which VHF amateur service bands have frequencies available for space stations?

Back 43

D. 2 meters

Front 44

Which amateur service UHF bands have frequencies available for a space station?

Back 44

B. 70 cm, 23 cm, 13 cm

Front 45

Which amateur stations are eligible to be telecommand stations?

Back 45

B. Any amateur station so designated by the space station licensee, subject to the privileges of the class of operator license held by the control operator

Front 46

Which amateur stations are eligible to operate as Earth stations?

Back 46

D. Any amateur station, subject to the privileges of the class of operator license held by the control operator

Front 47

What is the minimum number of qualified VEs required to administer an Element 4 amateur operator license examination?

Back 47

D. 3

Front 48

Where are the questions for all written US amateur license examinations listed?

Back 48

C. In a question pool maintained by all the VECs

Front 49

What is a Volunteer Examiner Coordinator?

Back 49

C. An organization that has entered into an agreement with the FCC to coordinate amateur operator license examinations

Front 50

Which of the following best describes the Volunteer Examiner accreditation process?

Back 50

D. The procedure by which a VEC confirms that the VE applicant meets FCC requirements to serve as an examiner

Front 51

What is the minimum passing score on amateur operator license examinations?

Back 51

B. Minimum passing score of 74%

Front 52

Who is responsible for the proper conduct and necessary supervision during an amateur operator license examination session?

Back 52

C. Each administering VE

Front 53

What should a VE do if a candidate fails to comply with the examiner's instructions during an amateur operator license examination?

Back 53

B. Immediately terminate the candidate's examination

Front 54

To which of the following examinees may a VE not administer an examination?

Back 54

C. Relatives of the VE as listed in the FCC rules

Front 55

What may be the penalty for a VE who fraudulently administers or certifies an examination?

Back 55

A. Revocation of the VE's amateur station license grant and the suspension of the VE's amateur operator license grant

Front 56

What must the administering VEs do after the administration of a successful examination for an amateur operator license?

Back 56

C. They must submit the application document to the coordinating VEC according to the coordinating VEC instructions

Front 57

What must the VE team do if an examinee scores a passing grade on all examination elements needed for an upgrade or new license?

Back 57

B. Three VEs must certify that the examinee is qualified for the license grant and that they have complied with the administering VE requirements

Front 58

What must the VE team do with the application form if the examinee does not pass the exam?

Back 58

A. Return the application document to the examinee

Front 59

What are the consequences of failing to appear for re-administration of an examination when so directed by the FCC?

Back 59

A. The licensee's license will be cancelled

Front 60

For which types of out-of-pocket expenses do the Part 97 rules state that VEs and VECs may be reimbursed?

Back 60

A. Preparing, processing, administering and coordinating an examination for an amateur radio license

Front 61

On what frequencies are spread spectrum transmissions permitted?

Back 61

B. Only on amateur frequencies above 222 MHz

Front 62

Which of the following operating arrangements allows an FCC-licensed US citizen to operate in many European countries, and alien amateurs from many European countries to operate in the US?

Back 62

A. CEPT agreement

Front 63

Under what circumstances may a dealer sell an external RF power amplifier capable of operation below 144 MHz if it has not been granted FCC certification?

Back 63

A. It was purchased in used condition from an amateur operator and is sold to another amateur operator for use at that operator's station

Front 64

Which of the following geographic descriptions approximately describes "Line A"?

Back 64

A. A line roughly parallel to and south of the US-Canadian border

Front 65

Amateur stations may not transmit in which of the following frequency segments if they are located in the contiguous 48 states and north of Line A?

Back 65

D. 420 - 430 MHz

Front 66

What is the National Radio Quiet Zone?

Back 66

C. An area surrounding the National Radio Astronomy Observatory

Front 67

When may an amateur station send a message to a business?

Back 67

D. When neither the amateur nor his or her employer has a pecuniary interest in the communications

Front 68

Which of the following types of amateur station communications are prohibited?

Back 68

A. Communications transmitted for hire or material compensation, except as otherwise provided in the rules

Front 69

Which of the following conditions apply when transmitting spread spectrum emission?

Back 69

D. All of these choices are correct

Front 70

What is the maximum transmitter power for an amateur station transmitting spread spectrum communications?

Back 70

C. 10 W

Front 71

Which of the following best describes one of the standards that must be met by an external RF power amplifier if it is to qualify for a grant of FCC certification?

Back 71

D. It must satisfy the FCC's spurious emission standards when operated at the lesser of 1500 watts, or its full output power

Front 72

Who may be the control operator of an auxiliary station?

Back 72

B. Only Technician, General, Advanced or Amateur Extra Class operators

Front 73

What types of communications may be transmitted to amateur stations in foreign countries?

Back 73

C. Communications incidental to the purpose of the amateur service and remarks of a personal nature

Front 74

Under what circumstances might the FCC issue a "Special Temporary Authority" (STA) to an amateur station?

Back 74

A. To provide for experimental amateur communications

Front 75

What is the direction of an ascending pass for an amateur satellite?

Back 75

C. From south to north

Front 76

What is the direction of a descending pass for an amateur satellite?

Back 76

A. From north to south

Front 77

What is the orbital period of an Earth satellite?

Back 77

C. The time it takes for a satellite to complete one revolution around the Earth

Front 78

What is meant by the term mode as applied to an amateur radio satellite?

Back 78

B. The satellite's uplink and downlink frequency bands

Front 79

What do the letters in a satellite's mode designator specify?

Back 79

D. The uplink and downlink frequency ranges

Front 80

On what band would a satellite receive signals if it were operating in mode U/V?

Back 80

A. 435-438 MHz

Front 81

Which of the following types of signals can be relayed through a linear transponder?

Back 81

D. All of these choices are correct

Front 82

Why should effective radiated power to a satellite which uses a linear transponder be limited?

Back 82

B. To avoid reducing the downlink power to all other users

Front 83

What do the terms L band and S band specify with regard to satellite communications?

Back 83

A. The 23 centimeter and 13 centimeter bands

Front 84

Why may the received signal from an amateur satellite exhibit a rapidly repeating fading effect?

Back 84

A. Because the satellite is spinning

Front 85

What type of antenna can be used to minimize the effects of spin modulation and Faraday rotation?

Back 85

B. A circularly polarized antenna

Front 86

What is one way to predict the location of a satellite at a given time?

Back 86

D. By calculations using the Keplerian elements for the specified satellite

Front 87

What type of satellite appears to stay in one position in the sky?

Back 87

B. Geostationary

Front 88

How many times per second is a new frame transmitted in a fast-scan (NTSC) television system?

Back 88

A. 30

Front 89

How many horizontal lines make up a fast-scan (NTSC) television frame?

Back 89

C. 525

Front 90

How is an interlaced scanning pattern generated in a fast-scan (NTSC) television system?

Back 90

D. By scanning odd numbered lines in one field and even numbered ones in the next

Front 91

What is blanking in a video signal?

Back 91

B. Turning off the scanning beam while it is traveling from right to left or from bottom to top

Front 92

Which of the following is an advantage of using vestigial sideband for standard fast- scan TV transmissions?

Back 92

C. Vestigial sideband reduces bandwidth while allowing for simple video detector circuitry

Front 93

What is vestigial sideband modulation?

Back 93

A. Amplitude modulation in which one complete sideband and a portion of the other are transmitted

Front 94

What is the name of the signal component that carries color information in NTSC video?

Back 94

B. Chroma

Front 95

Which of the following is a common method of transmitting accompanying audio with amateur fast-scan television?

Back 95

D. All of these choices are correct

Front 96

What hardware, other than a receiver with SSB capability and a suitable computer, is needed to decode SSTV using Digital Radio Mondiale (DRM)?

Back 96

D. No other hardware is needed

Front 97

Which of the following is an acceptable bandwidth for Digital Radio Mondiale (DRM) based voice or SSTV digital transmissions made on the HF amateur bands?

Back 97

A. 3 KHz

Front 98

What is the function of the Vertical Interval Signaling (VIS) code transmitted as part of an SSTV transmission?

Back 98

B. To identify the SSTV mode being used

Front 99

How are analog SSTV images typically transmitted on the HF bands?

Back 99

D. Varying tone frequencies representing the video are transmitted using single sideband

Front 100

How many lines are commonly used in each frame on an amateur slow-scan color television picture?

Back 100

C. 128 or 256

Front 101

What aspect of an amateur slow-scan television signal encodes the brightness of the picture?

Back 101

A. Tone frequency

Front 102

What signals SSTV receiving equipment to begin a new picture line?

Back 102

A. Specific tone frequencies

Front 103

Which of the following is the video standard used by North American Fast Scan ATV stations?

Back 103

D. NTSC

Front 104

What is the approximate bandwidth of a slow-scan TV signal?

Back 104

B. 3 kHz

Front 105

On which of the following frequencies is one likely to find FM ATV transmissions?

Back 105

D. 1255 MHz

Front 106

What special operating frequency restrictions are imposed on slow scan TV transmissions?

Back 106

C. They are restricted to phone band segments and their bandwidth can be no greater than that of a voice signal of the same modulation type

Front 107

Which of the following is true about contest operating?

Back 107

A. Operators are permitted to make contacts even if they do not submit a log

Front 108

Which of the following best describes the term "self-spotting" in regards to contest operating?

Back 108

A. The generally prohibited practice of posting one's own call sign and frequency on a call sign spotting network

Front 109

From which of the following bands is amateur radio contesting generally excluded?

Back 109

A. 30 meters

Front 110

On which of the following frequencies is an amateur radio contest contact generally discouraged?

Back 110

D. 146.52 MHz

Front 111

What is the function of a DX QSL Manager?

Back 111

B. To handle the receiving and sending of confirmation cards for a DX station

Front 112

During a VHF/UHF contest, in which band segment would you expect to find the highest level of activity?

Back 112

C. In the weak signal segment of the band, with most of the activity near the calling frequency

Front 113

What is the Cabrillo format?

Back 113

A. A standard for submission of electronic contest logs

Front 114

Why are received spread-spectrum signals resistant to interference?

Back 114

A. Signals not using the spectrum-spreading algorithm are suppressed in the receiver

Front 115

How does the spread-spectrum technique of frequency hopping work?

Back 115

D. The frequency of the transmitted signal is changed very rapidly according to a particular sequence also used by the receiving station

Front 116

Why might a DX station state that they are listening on another frequency?

Back 116

D. All of these choices are correct

Front 117

How should you generally identify your station when attempting to contact a DX station working a pileup or in a contest?

Back 117

A. Send your full call sign once or twice

Front 118

What might help to restore contact when DX signals become too weak to copy across an entire HF band a few hours after sunset?

Back 118

B. Switch to a lower frequency HF band

Front 119

Which of the following digital modes is especially designed for use for meteor scatter signals?

Back 119

B. FSK441

Front 120

What is the definition of baud?

Back 120

A. The number of data symbols transmitted per second

Front 121

Which of the following digital modes is especially useful for EME communications?

Back 121

D. JT65

Front 122

What is the purpose of digital store-and-forward functions on an Amateur Radio satellite?

Back 122

C. To store digital messages in the satellite for later download by other stations

Front 123

Which of the following techniques is normally used by low Earth orbiting digital satellites to relay messages around the world?

Back 123

B. Store-and-forward

Front 124

Which of the following is a commonly used 2-meter APRS frequency?

Back 124

A. 144.39 MHz

Front 125

Which of the following digital protocols is used by APRS?

Back 125

C. AX.25

Front 126

Which of the following types of packet frames is used to transmit APRS beacon data?

Back 126

A. Unnumbered Information

Front 127

Under clear communications conditions, which of these digital communications modes has the fastest data throughput?

Back 127

D. 300-baud packet

Front 128

How can an APRS station be used to help support a public service communications activity?

Back 128

C. An APRS station with a GPS unit can automatically transmit information to show a mobile station's position during the event

Front 129

Which of the following data are used by the APRS network communicate your location?

Back 129

D. Latitude and longitude

Front 130

How does JT65 improve EME communications?

Back 130

A. It can decode signals many dB below the noise floor using FEC

Front 131

Which type of modulation is common for data emissions below 30 MHz?

Back 131

B. FSK

Front 132

What do the letters FEC mean as they relate to digital operation?

Back 132

A. Forward Error Correction

Front 133

How is Forward Error Correction implemented?

Back 133

C. By transmitting extra data that may be used to detect and correct transmission errors

Front 134

What is indicated when one of the ellipses in an FSK crossed-ellipse display suddenly disappears?

Back 134

A. Selective fading has occurred

Front 135

How does ARQ accomplish error correction?

Back 135

D. If errors are detected, a retransmission is requested

Front 136

What is the most common data rate used for HF packet communications?

Back 136

C. 300 baud

Front 137

What is the typical bandwidth of a properly modulated MFSK16 signal?

Back 137

B. 316 Hz

Front 138

Which of the following HF digital modes can be used to transfer binary files?

Back 138

B. PACTOR

Front 139

Which of the following HF digital modes uses variable-length coding for bandwidth efficiency?

Back 139

D. PSK31

Front 140

Which of these digital communications modes has the narrowest bandwidth?

Back 140

C. PSK31

Front 141

What is the difference between direct FSK and audio FSK?

Back 141

A. Direct FSK applies the data signal to the transmitter VFO

Front 142

Which type of digital communication does not support keyboard-to-keyboard operation?

Back 142

A. Winlink

Front 143

What is the approximate maximum separation measured along the surface of the Earth between two stations communicating by Moon bounce?

Back 143

D. 12,000 miles, as long as both can "see" the Moon

Front 144

What characterizes libration fading of an Earth-Moon-Earth signal?

Back 144

B. A fluttery irregular fading

Front 145

When scheduling EME contacts, which of these conditions will generally result in the least path loss?

Back 145

A. When the Moon is at perigee

Front 146

What type of receiving system is desirable for EME communications?

Back 146

D. Equipment with very low noise figures

Front 147

Which of the following describes a method of establishing EME contacts?

Back 147

A. Time synchronous transmissions with each station alternating

Front 148

What frequency range would you normally tune to find EME signals in the 2 meter band?

Back 148

B. 144.000 - 144.100 MHz

Front 149

What frequency range would you normally tune to find EME signals in the 70 cm band?

Back 149

D. 432.000 - 432.100 MHz

Front 150

When a meteor strikes the Earth's atmosphere, a cylindrical region of free electrons is formed at what layer of the ionosphere?

Back 150

A. The E layer

Front 151

Which of the following frequency ranges is well suited for meteor-scatter communications?

Back 151

C. 28 - 148 MHz

Front 152

Which of the following is a good technique for making meteor-scatter contacts?

Back 152

D. All of these choices are correct

Front 153

What is transequatorial propagation?

Back 153

A. Propagation between two mid-latitude points at approximately the same distance north and south of the magnetic equator

Front 154

What is the approximate maximum range for signals using transequatorial propagation?

Back 154

C. 5000 miles

Front 155

What is the best time of day for transequatorial propagation?

Back 155

C. Afternoon or early evening

Front 156

What type of propagation is probably occurring if an HF beam antenna must be pointed in a direction 180 degrees away from a station to receive the strongest signals?

Back 156

A. Long-path

Front 157

Which amateur bands typically support long-path propagation?

Back 157

C. 160 to 10 meters

Front 158

Which of the following amateur bands most frequently provides long-path propagation?

Back 158

B. 20 meters

Front 159

Which of the following could account for hearing an echo on the received signal of a distant station?

Back 159

D. Receipt of a signal by more than one path

Front 160

What type of HF propagation is probably occurring if radio signals travel along the terminator between daylight and darkness?

Back 160

D. Gray-line

Front 161

At what time of day is gray-line propagation most likely to occur?

Back 161

A. At sunrise and sunset

Front 162

What is the cause of gray-line propagation?

Back 162

B. At twilight, D-layer absorption drops while E-layer and F-layer propagation remain strong

Front 163

Which of the following describes gray-line propagation?

Back 163

C. Long distance communications at twilight on frequencies less than 15 MHz

Front 164

Which of the following effects does Aurora activity have on radio communications?

Back 164

D. All of these choices are correct

Front 165

What is the cause of Aurora activity?

Back 165

C. The interaction of charged particles from the Sun with the Earth's magnetic field and the ionosphere

Front 166

Where in the ionosphere does Aurora activity occur?

Back 166

D. In the E-region

Front 167

Which emission mode is best for Aurora propagation?

Back 167

A. CW

Front 168

Which of the following describes selective fading?

Back 168

B. Partial cancellation of some frequencies within the received pass band

Front 169

By how much does the VHF/UHF radio-path horizon distance exceed the geometric horizon?

Back 169

A. By approximately 15% of the distance

Front 170

How does the radiation pattern of a horizontally polarized 3-element beam antenna vary with its height above ground?

Back 170

B. The main lobe takeoff angle decreases with increasing height

Front 171

What is the name of the high-angle wave in HF propagation that travels for some distance within the F2 region?

Back 171

B. Pedersen ray

Front 172

Which of the following is usually responsible for causing VHF signals to propagate for hundreds of miles?

Back 172

C. Tropospheric ducting

Front 173

How does the performance of a horizontally polarized antenna mounted on the side of a hill compare with the same antenna mounted on flat ground?

Back 173

B. The main lobe takeoff angle decreases in the downhill direction

Front 174

From the contiguous 48 states, in which approximate direction should an antenna be pointed to take maximum advantage of aurora propagation?

Back 174

B. North

Front 175

How does the maximum distance of ground-wave propagation change when the signal frequency is increased?

Back 175

C. It decreases

Front 176

What type of polarization is best for ground-wave propagation?

Back 176

A. Vertical

Front 177

Why does the radio-path horizon distance exceed the geometric horizon?

Back 177

D. Downward bending due to density variations in the atmosphere

Front 178

How does a spectrum analyzer differ from an oscilloscope?

Back 178

C. A spectrum analyzer displays signals in the frequency domain; an oscilloscope displays signals in the time domain

Front 179

Which of the following parameters would a spectrum analyzer display on the horizontal axis?

Back 179

D. Frequency

Front 180

Which of the following parameters would a spectrum analyzer display on the vertical axis?

Back 180

A. Amplitude

Front 181

Which of the following test instruments is used to display spurious signals from a radio transmitter?

Back 181

A. A spectrum analyzer

Front 182

Which of the following test instruments is used to display intermodulation distortion products in an SSB transmission?

Back 182

B. A spectrum analyzer

Front 183

Which of the following could be determined with a spectrum analyzer?

Back 183

D. All of these choices are correct

Front 184

Which of the following is an advantage of using an antenna analyzer compared to an SWR bridge to measure antenna SWR?

Back 184

B. Antenna analyzers do not need an external RF source

Front 185

Which of the following instruments would be best for measuring the SWR of a beam antenna?

Back 185

D. An antenna analyzer

Front 186

Which of the following describes a good method for measuring the intermodulation distortion of your own PSK signal?

Back 186

A. Transmit into a dummy load, receive the signal on a second receiver, and feed the audio into the sound card of a computer running an appropriate PSK program

Front 187

Which of the following tests establishes that a silicon NPN junction transistor is biased on?

Back 187

C. Measure base-to-emitter voltage with a voltmeter; it should be approximately

Front 188

Which of these instruments could be used for detailed analysis of digital signals?

Back 188

B. Oscilloscope

Front 189

Which of the following procedures is an important precaution to follow when connecting a spectrum analyzer to a transmitter output?

Back 189

B. Attenuate the transmitter output going to the spectrum analyzer

Front 190

Which of the following factors most affects the accuracy of a frequency counter?

Back 190

B. Time base accuracy

Front 191

What is an advantage of using a bridge circuit to measure impedance?

Back 191

C. The measurement is based on obtaining a signal null, which can be done very precisely

Front 192

If a frequency counter with a specified accuracy of +/- 1.0 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?

Back 192

C. 146.52 Hz

Front 193

If a frequency counter with a specified accuracy of +/- 0.1 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?

Back 193

A. 14.652 Hz

Front 194

If a frequency counter with a specified accuracy of +/- 10 ppm reads 146,520,000 Hz, what is the most the actual frequency being measured could differ from the reading?

Back 194

D. 1465.20 Hz

Front 195

How much power is being absorbed by the load when a directional power meter connected between a transmitter and a terminating load reads 100 watts forward power and 25 watts reflected power?

Back 195

D. 75 watts

Front 196

Which of the following is good practice when using an oscilloscope probe?

Back 196

A. Keep the signal ground connection of the probe as short as possible

Front 197

Which of the following is a characteristic of a good DC voltmeter?

Back 197

C. High impedance input

Front 198

What is indicated if the current reading on an RF ammeter placed in series with the antenna feed line of a transmitter increases as the transmitter is tuned to resonance?

Back 198

D. There is more power going into the antenna

Front 199

Which of the following describes a method to measure intermodulation distortion in an SSB transmitter?

Back 199

B. Modulate the transmitter with two non-harmonically related audio frequencies and observe the RF output with a spectrum analyzer

Front 200

How should a portable antenna analyzer be connected when measuring antenna resonance and feed point impedance?

Back 200

D. Connect the antenna feed line directly to the analyzer's connector

Front 201

What is the significance of voltmeter sensitivity expressed in ohms per volt?

Back 201

A. The full scale reading of the voltmeter multiplied by its ohms per volt rating will provide the input impedance of the voltmeter

Front 202

How is the compensation of an oscilloscope probe typically adjusted?

Back 202

A. A square wave is displayed and the probe is adjusted until the horizontal portions of the displayed wave are as nearly flat as possible

Front 203

What happens if a dip meter is too tightly coupled to a tuned circuit being checked?

Back 203

B. A less accurate reading results

Front 204

Which of the following can be used as a relative measurement of the Q for a series-tuned circuit?

Back 204

C. The bandwidth of the circuit's frequency response

Front 205

What is an effect of excessive phase noise in the local oscillator section of a receiver?

Back 205

D. It can cause strong signals on nearby frequencies to interfere with reception of weak signals

Front 206

Which of the following portions of a receiver can be effective in eliminating image signal interference?

Back 206

A. A front-end filter or pre-selector

Front 207

What is the term for the blocking of one FM phone signal by another, stronger FM phone signal?

Back 207

C. Capture effect

Front 208

What is the definition of the noise figure of a receiver?

Back 208

D. The ratio in dB of the noise generated by the receiver compared to the theoretical minimum noise

Front 209

What does a value of -174 dBm/Hz represent with regard to the noise floor of a receiver?

Back 209

B. The theoretical noise at the input of a perfect receiver at room temperature

Front 210

A CW receiver with the AGC off has an equivalent input noise power density of -174 dBm/Hz. What would be the level of an unmodulated carrier input to this receiver that would yield an audio output SNR of 0 dB in a 400 Hz noise bandwidth?

Back 210

D. -148 dBm

Front 211

What does the MDS of a receiver represent?

Back 211

B. The minimum discernible signal

Front 212

How might lowering the noise figure affect receiver performance?

Back 212

B. It would improve weak signal sensitivity

Front 213

Which of the following choices is a good reason for selecting a high frequency for the design of the IF in a conventional HF or VHF communications receiver?

Back 213

C. Easier for front-end circuitry to eliminate image responses

Front 214

Which of the following is a desirable amount of selectivity for an amateur RTTY HF receiver?

Back 214

B. 300 Hz

Front 215

Which of the following is a desirable amount of selectivity for an amateur SSB phone receiver?

Back 215

B. 2.4 kHz

Front 216

What is an undesirable effect of using too wide a filter bandwidth in the IF section of a receiver?

Back 216

D. Undesired signals may be heard

Front 217

How does a narrow-band roofing filter affect receiver performance?

Back 217

C. It improves dynamic range by attenuating strong signals near the receive frequency

Front 218

On which of the following frequencies might a signal be transmitting which is generating a spurious image signal in a receiver tuned to 14.300 MHz and which uses a 455 kHz IF frequency?

Back 218

D. 15.210 MHz

Front 219

What is the primary source of noise that can be heard from an HF receiver with an antenna connected?

Back 219

D. Atmospheric noise

Front 220

What is meant by the blocking dynamic range of a receiver?

Back 220

A. The difference in dB between the noise floor and the level of an incoming signal which will cause 1 dB of gain compression

Front 221

Which of the following describes two problems caused by poor dynamic range in a communications receiver?

Back 221

A. Cross-modulation of the desired signal and desensitization from strong adjacent signals

Front 222

How can intermodulation interference between two repeaters occur?

Back 222

B. When the repeaters are in close proximity and the signals mix in the final amplifier of one or both transmitters

Front 223

Which of the following may reduce or eliminate intermodulation interference in a repeater caused by another transmitter operating in close proximity?

Back 223

B. A properly terminated circulator at the output of the transmitter

Front 224

What transmitter frequencies would cause an intermodulation-product signal in a receiver tuned to 146.70 MHz when a nearby station transmits on 146.52 MHz?

Back 224

A. 146.34 MHz and 146.61 MHz

Front 225

What is the term for unwanted signals generated by the mixing of two or more signals?

Back 225

D. Intermodulation interference

Front 226

Which of the following describes the most significant effect of an off-frequency signal when it is causing cross-modulation interference to a desired signal?

Back 226

D. The off-frequency unwanted signal is heard in addition to the desired signal

Front 227

What causes intermodulation in an electronic circuit?

Back 227

C. Nonlinear circuits or devices

Front 228

What is the purpose of the preselector in a communications receiver?

Back 228

C. To increase rejection of unwanted signals

Front 229

What does a third-order intercept level of 40 dBm mean with respect to receiver performance?

Back 229

C. A pair of 40 dBm signals will theoretically generate a third-order intermodulation product with the same level as the input signals

Front 230

Why are third-order intermodulation products created within a receiver of particular interest compared to other products?

Back 230

A. The third-order product of two signals which are in the band of interest is also likely to be within the band

Front 231

What is the term for the reduction in receiver sensitivity caused by a strong signal near the received frequency?

Back 231

A. Desensitization

Front 232

Which of the following can cause receiver desensitization?

Back 232

B. Strong adjacent-channel signals

Front 233

Which of the following is a way to reduce the likelihood of receiver desensitization?

Back 233

A. Decrease the RF bandwidth of the receiver

Front 234

Which of the following types of receiver noise can often be reduced by use of a receiver noise blanker?

Back 234

A. Ignition noise

Front 235

Which of the following types of receiver noise can often be reduced with a DSP noise filter?

Back 235

D. All of these choices are correct

Front 236

Which of the following signals might a receiver noise blanker be able to remove from desired signals?

Back 236

B. Signals which appear across a wide bandwidth

Front 237

How can conducted and radiated noise caused by an automobile alternator be suppressed?

Back 237

D. By connecting the radio's power leads directly to the battery and by installing coaxial capacitors in line with the alternator leads

Front 238

How can noise from an electric motor be suppressed?

Back 238

B. By installing a brute-force AC-line filter in series with the motor leads

Front 239

What is a major cause of atmospheric static?

Back 239

B. Thunderstorms

Front 240

How can you determine if line noise interference is being generated within your home?

Back 240

C. By turning off the AC power line main circuit breaker and listening on a battery operated radio

Front 241

What type of signal is picked up by electrical wiring near a radio antenna?

Back 241

A. A common-mode signal at the frequency of the radio transmitter

Front 242

What undesirable effect can occur when using an IF noise blanker?

Back 242

C. Nearby signals may appear to be excessively wide even if they meet emission standards

Front 243

What is a common characteristic of interference caused by a touch controlled electrical device?

Back 243

D. All of these choices are correct

Front 244

Which of the following is the most likely cause if you are hearing combinations of local AM broadcast signals within one or more of the MF or HF ham bands?

Back 244

B. Nearby corroded metal joints are mixing and re-radiating the broadcast signals

Front 245

What is one disadvantage of using some types of automatic DSP notch-filters when attempting to copy CW signals?

Back 245

A. The DSP filter can remove the desired signal at the same time as it removes interfering signals

Front 246

What might be the cause of a loud roaring or buzzing AC line interference that comes and goes at intervals?

Back 246

D. All of these choices are correct

Front 247

What is one type of electrical interference that might be caused by the operation of a nearby personal computer?

Back 247

C. The appearance of unstable modulated or unmodulated signals at specific frequencies

Front 248

What can cause the voltage across reactances in series to be larger than the voltage applied to them?

Back 248

A. Resonance

Front 249

What is resonance in an electrical circuit?

Back 249

C. The frequency at which the capacitive reactance equals the inductive reactance

Front 250

What is the magnitude of the impedance of a series RLC circuit at resonance?

Back 250

D. Approximately equal to circuit resistance

Front 251

What is the magnitude of the impedance of a circuit with a resistor, an inductor and a capacitor all in parallel, at resonance?

Back 251

A. Approximately equal to circuit resistance

Front 252

What is the magnitude of the current at the input of a series RLC circuit as the frequency goes through resonance?

Back 252

B. Maximum

Front 253

What is the magnitude of the circulating current within the components of a parallel LC circuit at resonance?

Back 253

B. It is at a maximum

Front 254

What is the magnitude of the current at the input of a parallel RLC circuit at resonance?

Back 254

A. Minimum

Front 255

What is the phase relationship between the current through and the voltage across a series resonant circuit at resonance?

Back 255

C. The voltage and current are in phase

Front 256

What is the phase relationship between the current through and the voltage across a parallel resonant circuit at resonance?

Back 256

C. The voltage and current are in phase

Front 257

What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 1.8 MHz and a Q of 95?

Back 257

A. 18.9 kHz

Front 258

What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 7.1 MHz and a Q of 150?

Back 258

C. 47.3 kHz

Front 259

What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 3.7 MHz and a Q of 118?

Back 259

C. 31.4 kHz

Front 260

What is the half-power bandwidth of a parallel resonant circuit that has a resonant frequency of 14.25 MHz and a Q of 187?

Back 260

B. 76.2 kHz

Front 261

What is the resonant frequency of a series RLC circuit if R is 22 ohms, L is 50 microhenrys and C is 40 picofarads?

Back 261

C. 3.56 MHz

Front 262

What is the resonant frequency of a series RLC circuit if R is 56 ohms, L is 40 microhenrys and C is 200 picofarads?

Back 262

B. 1.78 MHz

Front 263

What is the resonant frequency of a parallel RLC circuit if R is 33 ohms, L is 50 microhenrys and C is 10 picofarads?

Back 263

D. 7.12 MHz

Front 264

What is the resonant frequency of a parallel RLC circuit if R is 47 ohms, L is 25 microhenrys and C is 10 picofarads?

Back 264

A. 10.1 MHz

Front 265

What is the term for the time required for the capacitor in an RC circuit to be charged to 63.2% of the applied voltage?

Back 265

B. One time constant

Front 266

What is the term for the time it takes for a charged capacitor in an RC circuit to discharge to 36.8% of its initial voltage?

Back 266

D. One time constant

Front 267

The capacitor in an RC circuit is discharged to what percentage of the starting voltage after two time constants?

Back 267

D. 13.5%

Front 268

What is the time constant of a circuit having two 220-microfarad capacitors and two 1-megohm resistors, all in parallel?

Back 268

D. 220 seconds

Front 269

How long does it take for an initial charge of 20 V DC to decrease to 7.36 V DC in a 0.01-microfarad capacitor when a 2-megohm resistor is connected across it?

Back 269

A. 0.02 seconds

Front 270

How long does it take for an initial charge of 800 V DC to decrease to 294 V DC in a 450-microfarad capacitor when a 1-megohm resistor is connected across it?

Back 270

C. 450 seconds

Front 271

What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 500 ohms, R is 1 kilohm, and XL is 250 ohms?

Back 271

C. 14.0 degrees with the voltage lagging the current

Front 272

What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 100 ohms, R is 100 ohms, and XL is 75 ohms?

Back 272

A. 14 degrees with the voltage lagging the current

Front 273

What is the relationship between the current through a capacitor and the voltage across a capacitor?

Back 273

D. Current leads voltage by 90 degrees

Front 274

What is the relationship between the current through an inductor and the voltage across an inductor?

Back 274

A. Voltage leads current by 90 degrees

Front 275

What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 25 ohms, R is 100 ohms, and XL is 50 ohms?

Back 275

B. 14 degrees with the voltage leading the current

Front 276

What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 75 ohms, R is 100 ohms, and XL is 50 ohms?

Back 276

C. 14 degrees with the voltage lagging the current

Front 277

What is the phase angle between the voltage across and the current through a series RLC circuit if XC is 250 ohms, R is 1 kilohm, and XL is 500 ohms?

Back 277

D. 14.04 degrees with the voltage leading the current

Front 278

In polar coordinates, what is the impedance of a network consisting of a 100-ohm-reactance inductor in series with a 100-ohm resistor?

Back 278

B. 141 ohms at an angle of 45 degrees

Front 279

In polar coordinates, what is the impedance of a network consisting of a 100-ohm-reactance inductor, a 100-ohm-reactance capacitor, and a 100-ohm resistor, all connected in series?

Back 279

D. 100 ohms at an angle of 0 degrees

Front 280

In polar coordinates, what is the impedance of a network consisting of a 300-ohm-reactance capacitor, a 600-ohm-reactance inductor, and a 400-ohm resistor, all connected in series?

Back 280

A. 500 ohms at an angle of 37 degrees

Front 281

In polar coordinates, what is the impedance of a network consisting of a 400-ohm-reactance capacitor in series with a 300-ohm resistor?

Back 281

D. 500 ohms at an angle of -53.1 degrees

Front 282

In polar coordinates, what is the impedance of a network consisting of a 400-ohm-reactance inductor in parallel with a 300-ohm resistor?

Back 282

A. 240 ohms at an angle of 36.9 degrees

Front 283

In polar coordinates, what is the impedance of a network consisting of a 100-ohm-reactance capacitor in series with a 100-ohm resistor?

Back 283

D. 141 ohms at an angle of -45 degrees

Front 284

In polar coordinates, what is the impedance of a network comprised of a 100-ohm-reactance capacitor in parallel with a 100-ohm resistor?

Back 284

C. 71 ohms at an angle of -45 degrees

Front 285

In polar coordinates, what is the impedance of a network comprised of a 300-ohm-reactance inductor in series with a 400-ohm resistor?

Back 285

B. 500 ohms at an angle of 37 degrees

Front 286

When using rectangular coordinates to graph the impedance of a circuit, what does the horizontal axis represent?

Back 286

A. Resistive component

Front 287

When using rectangular coordinates to graph the impedance of a circuit, what does the vertical axis represent?

Back 287

B. Reactive component

Front 288

What do the two numbers represent that are used to define a point on a graph using rectangular coordinates?

Back 288

C. The coordinate values along the horizontal and vertical axes

Front 289

If you plot the impedance of a circuit using the rectangular coordinate system and find the impedance point falls on the right side of the graph on the horizontal axis, what do you know about the circuit?

Back 289

D. It is equivalent to a pure resistance

Front 290

What coordinate system is often used to display the resistive, inductive, and/or capacitive reactance components of an impedance?

Back 290

D. Rectangular coordinates

Front 291

What coordinate system is often used to display the phase angle of a circuit containing resistance, inductive and/or capacitive reactance?

Back 291

D. Polar coordinates

Front 292

In polar coordinates, what is the impedance of a circuit of 100 -j100 ohms impedance?

Back 292

A. 141 ohms at an angle of -45 degrees

Front 293

In polar coordinates, what is the impedance of a circuit that has an admittance of 7.09 millisiemens at 45 degrees?

Back 293

B. 141 ohms at an angle of -45 degrees

Front 294

In rectangular coordinates, what is the impedance of a circuit that has an admittance of 5 millisiemens at -30 degrees?

Back 294

C. 173 +j100 ohms

Front 295

In polar coordinates, what is the impedance of a series circuit consisting of a resistance of 4 ohms, an inductive reactance of 4 ohms, and a capacitive reactance of 1 ohm?

Back 295

B. 5 ohms at an angle of 37 degrees

Front 296

Which point on Figure E5-2 best represents that impedance of a series circuit consisting of a 400 ohm resistor and a 38 picofarad capacitor at 14 MHz?

Back 296

B. Point 4

Front 297

Which point in Figure E5-2 best represents the impedance of a series circuit consisting of a 300 ohm resistor and an 18 microhenry inductor at 3.505 MHz?

Back 297

B. Point 3

Front 298

Which point on Figure E5-2 best represents the impedance of a series circuit consisting of a 300 ohm resistor and a 19 picofarad capacitor at 21.200 MHz?

Back 298

A. Point 1

Front 299

In rectangular coordinates, what is the impedance of a network consisting of a 10-microhenry inductor in series with a 40-ohm resistor at 500 MHz?

Back 299

A. 40 + j31,400

Front 300

Which point on Figure E5-2 best represents the impedance of a series circuit consisting of a 300-ohm resistor, a 0.64-microhenry inductor and an 85-picofarad capacitor at 24.900 MHz?

Back 300

D. Point 8

Front 301

What is the result of skin effect?

Back 301

A. As frequency increases, RF current flows in a thinner layer of the conductor, closer to the surface

Front 302

Why is the resistance of a conductor different for RF currents than for direct currents?

Back 302

C. Because of skin effect

Front 303

What device is used to store electrical energy in an electrostatic field?

Back 303

C. A capacitor

Front 304

What unit measures electrical energy stored in an electrostatic field?

Back 304

B. Joule

Front 305

Which of the following creates a magnetic field?

Back 305

B. Electric current

Front 306

In what direction is the magnetic field oriented about a conductor in relation to the direction of electron flow?

Back 306

D. In a direction determined by the left-hand rule

Front 307

What determines the strength of a magnetic field around a conductor?

Back 307

D. The amount of current

Front 308

What type of energy is stored in an electromagnetic or electrostatic field?

Back 308

B. Potential energy

Front 309

What happens to reactive power in an AC circuit that has both ideal inductors and ideal capacitors?

Back 309

B. It is repeatedly exchanged between the associated magnetic and electric fields, but is not dissipated

Front 310

How can the true power be determined in an AC circuit where the voltage and current are out of phase?

Back 310

A. By multiplying the apparent power times the power factor

Front 311

What is the power factor of an R-L circuit having a 60 degree phase angle between the voltage and the current?

Back 311

C. 0.5

Front 312

How many watts are consumed in a circuit having a power factor of 0.2 if the input is 100-V AC at 4 amperes?

Back 312

B. 80 watts

Front 313

How much power is consumed in a circuit consisting of a 100 ohm resistor in series with a 100 ohm inductive reactance drawing 1 ampere?

Back 313

B. 100 Watts

Front 314

What is reactive power?

Back 314

A. Wattless, nonproductive power

Front 315

What is the power factor of an RL circuit having a 45 degree phase angle between the voltage and the current?

Back 315

D. 0.707

Front 316

What is the power factor of an RL circuit having a 30 degree phase angle between the voltage and the current?

Back 316

C. 0.866

Front 317

How many watts are consumed in a circuit having a power factor of 0.6 if the input is 200V AC at 5 amperes?

Back 317

D. 600 watts

Front 318

How many watts are consumed in a circuit having a power factor of 0.71 if the apparent power is 500 VA?

Back 318

B. 355 W

Front 319

In what application is gallium arsenide used as a semiconductor material in preference to germanium or silicon?

Back 319

C. At microwave frequencies

Front 320

Which of the following semiconductor materials contains excess free electrons?

Back 320

A. N-type

Front 321

What are the majority charge carriers in P-type semiconductor material?

Back 321

C. Holes

Front 322

What is the name given to an impurity atom that adds holes to a semiconductor crystal structure?

Back 322

C. Acceptor impurity

Front 323

What is the alpha of a bipolar junction transistor?

Back 323

C. The change of collector current with respect to emitter current

Front 324

What is the beta of a bipolar junction transistor?

Back 324

B. The change in collector current with respect to base current

Front 325

In Figure E6-1, what is the schematic symbol for a PNP transistor?

Back 325

A. 1

Front 326

What term indicates the frequency at which the grounded-base current gain of a transistor has decreased to 0.7 of the gain obtainable at 1 kHz?

Back 326

D. Alpha cutoff frequency

Front 327

What is a depletion-mode FET?

Back 327

A. An FET that exhibits a current flow between source and drain when no gate voltage is applied

Front 328

In Figure E6-2, what is the schematic symbol for an N-channel dual-gate MOSFET?

Back 328

B. 4

Front 329

In Figure E6-2, what is the schematic symbol for a P-channel junction FET?

Back 329

A. 1

Front 330

Why do many MOSFET devices have internally connected Zener diodes on the gates?

Back 330

D. To reduce the chance of the gate insulation being punctured by static discharges or excessive voltages

Front 331

What do the initials CMOS stand for?

Back 331

C. Complementary Metal-Oxide Semiconductor

Front 332

How does DC input impedance at the gate of a field-effect transistor compare with the DC input impedance of a bipolar transistor?

Back 332

C. An FET has high input impedance; a bipolar transistor has low input impedance

Front 333

Which of the following semiconductor materials contains an excess of holes in the outer shell of electrons?

Back 333

B. P-type

Front 334

What are the majority charge carriers in N-type semiconductor material?

Back 334

B. Free electrons

Front 335

What are the names of the three terminals of a field-effect transistor?

Back 335

D. Gate, drain, source

Front 336

What is the most useful characteristic of a Zener diode?

Back 336

B. A constant voltage drop under conditions of varying current

Front 337

What is an important characteristic of a Schottky diode as compared to an ordinary silicon diode when used as a power supply rectifier?

Back 337

D. Less forward voltage drop

Front 338

What special type of diode is capable of both amplification and oscillation?

Back 338

C. Tunnel

Front 339

What type of semiconductor device is designed for use as a voltage-controlled capacitor?

Back 339

A. Varactor diode

Front 340

What characteristic of a PIN diode makes it useful as an RF switch or attenuator?

Back 340

D. A large region of intrinsic material

Front 341

Which of the following is a common use of a hot-carrier diode?

Back 341

D. As a VHF / UHF mixer or detector

Front 342

What is the failure mechanism when a junction diode fails due to excessive current?

Back 342

B. Excessive junction temperature

Front 343

Which of the following describes a type of semiconductor diode?

Back 343

A. Metal-semiconductor junction

Front 344

What is a common use for point contact diodes?

Back 344

C. As an RF detector

Front 345

In Figure E6-3, what is the schematic symbol for a light-emitting diode?

Back 345

B. 5

Front 346

What is used to control the attenuation of RF signals by a PIN diode?

Back 346

A. Forward DC bias current

Front 347

What is one common use for PIN diodes?

Back 347

C. As an RF switch

Front 348

What type of bias is required for an LED to emit light?

Back 348

B. Forward bias

Front 349

What is the recommended power supply voltage for TTL series integrated circuits?

Back 349

C. 5 volts

Front 350

What logic state do the inputs of a TTL device assume if they are left open?

Back 350

A. A logic-high state

Front 351

Which of the following describes tri-state logic?

Back 351

A. Logic devices with 0, 1, and high impedance output states

Front 352

Which of the following is the primary advantage of tri-state logic?

Back 352

B. Ability to connect many device outputs to a common bus

Front 353

Which of the following is an advantage of CMOS logic devices over TTL devices?

Back 353

D. Lower power consumption

Front 354

Why do CMOS digital integrated circuits have high immunity to noise on the input signal or power supply?

Back 354

C. The input switching threshold is about one-half the power supply voltage

Front 355

In Figure E6-5, what is the schematic symbol for an AND gate?

Back 355

A. 1

Front 356

In Figure E6-5, what is the schematic symbol for a NAND gate?

Back 356

B. 2

Front 357

In Figure E6-5, what is the schematic symbol for an OR gate?

Back 357

B. 3

Front 358

In Figure E6-5, what is the schematic symbol for a NOR gate?

Back 358

D. 4

Front 359

In Figure E6-5, what is the schematic symbol for the NOT operation (inverter)?

Back 359

C. 5

Front 360

What is BiCMOS logic?

Back 360

D. An integrated circuit logic family using both bipolar and CMOS transistors

Front 361

Which of the following is an advantage of BiCMOS logic?

Back 361

C. It has the high input impedance of CMOS and the low output impedance of bipolar transistors

Front 362

What is cathode ray tube (CRT) persistence?

Back 362

D. The length of time the image remains on the screen after the beam is turned off

Front 363

Exceeding what design rating can cause a cathode ray tube (CRT) to generate X-rays?

Back 363

B. The anode voltage

Front 364

Which of the following is true of a charge-coupled device (CCD)?

Back 364

C. It samples an analog signal and passes it in stages from the input to the output

Front 365

What function does a charge-coupled device (CCD) serve in a modern video camera?

Back 365

A. It stores photogenerated charges as signals corresponding to pixels

Front 366

What is a liquid-crystal display (LCD)?

Back 366

B. A display using a crystalline liquid which, in conjunction with polarizing filters, becomes opaque when voltage is applied

Front 367

What core material property determines the inductance of a toroidal inductor?

Back 367

D. Permeability

Front 368

What is the usable frequency range of inductors that use toroidal cores, assuming a correct selection of core material for the frequency being used?

Back 368

B. From less than 20 Hz to approximately 300 MHz

Front 369

What is one important reason for using powdered-iron toroids rather than ferrite toroids in an inductor?

Back 369

B. Powdered-iron toroids generally maintain their characteristics at higher currents

Front 370

What devices are commonly used as VHF and UHF parasitic suppressors at the input and output terminals of transistorized HF amplifiers?

Back 370

C. Ferrite beads

Front 371

What is a primary advantage of using a toroidal core instead of a solenoidal core in an inductor?

Back 371

A. Toroidal cores confine most of the magnetic field within the core material

Front 372

How many turns will be required to produce a 1-mH inductor using a ferrite toroidal core that has an inductance index (A L) value of 523 millihenrys/1000 turns?

Back 372

C. 43 turns

Front 373

How many turns will be required to produce a 5-microhenry inductor using a powdered-iron toroidal core that has an inductance index (A L) value of 40 microhenrys/100 turns?

Back 373

A. 35 turns

Front 374

What type of CRT deflection is better when high-frequency waveforms are to be displayed on the screen?

Back 374

D. Electrostatic

Front 375

Which is NOT true of a charge-coupled device (CCD)?

Back 375

C. It is commonly used as an analog-to-digital converter

Front 376

What is the principle advantage of liquid-crystal display (LCD) devices over other types of display devices?

Back 376

A. They consume less power

Front 377

What is one reason for using ferrite toroids rather than powdered-iron toroids in an inductor?

Back 377

C. Ferrite toroids generally require fewer turns to produce a given inductance value

Front 378

What is a crystal lattice filter?

Back 378

D. A filter with narrow bandwidth and steep skirts made using quartz crystals

Front 379

Which of the following factors has the greatest effect in helping determine the bandwidth and response shape of a crystal ladder filter?

Back 379

A. The relative frequencies of the individual crystals

Front 380

What is one aspect of the piezoelectric effect?

Back 380

A. Physical deformation of a crystal by the application of a voltage

Front 381

What is the most common input and output impedance of circuits that use MMICs?

Back 381

A. 50 ohms

Front 382

Which of the following noise figure values is typical of a low-noise UHF preamplifier?

Back 382

A. 2 dB

Front 383

What characteristics of the MMIC make it a popular choice for VHF through microwave circuits?

Back 383

D. Controlled gain, low noise figure, and constant input and output impedance over the specified frequency range

Front 384

Which of the following is typically used to construct a MMIC-based microwave amplifier?

Back 384

B. Microstrip construction

Front 385

How is power-supply voltage normally furnished to the most common type of monolithic microwave integrated circuit (MMIC)?

Back 385

A. Through a resistor and/or RF choke connected to the amplifier output lead

Front 386

Which of the following must be done to insure that a crystal oscillator provides the frequency specified by the crystal manufacturer?

Back 386

B. Provide the crystal with a specified parallel capacitance

Front 387

What is the equivalent circuit of a quartz crystal?

Back 387

A. Motional capacitance, motional inductance and loss resistance in series, with a shunt capacitance representing electrode and stray capacitance

Front 388

Which of the following materials is likely to provide the highest frequency of operation when used in MMICs?

Back 388

D. Gallium nitride

Front 389

What is a "Jones filter" as used as part of a HF receiver IF stage?

Back 389

B. A variable bandwidth crystal lattice filter

Front 390

What is photoconductivity?

Back 390

B. The increased conductivity of an illuminated semiconductor

Front 391

What happens to the conductivity of a photoconductive material when light shines on it?

Back 391

A. It increases

Front 392

What is the most common configuration of an optoisolator or optocoupler?

Back 392

D. An LED and a phototransistor

Front 393

What is the photovoltaic effect?

Back 393

B. The conversion of light to electrical energy

Front 394

Which of the following describes an optical shaft encoder?

Back 394

A. A device which detects rotation of a control by interrupting a light source with a patterned wheel

Front 395

Which of these materials is affected the most by photoconductivity?

Back 395

A. A crystalline semiconductor

Front 396

What is a solid state relay?

Back 396

B. A device that uses semiconductor devices to implement the functions of an electromechanical relay

Front 397

Why are optoisolators often used in conjunction with solid state circuits when switching 120 VAC?

Back 397

C. Optoisolators provide a very high degree of electrical isolation between a control circuit and the circuit being switched

Front 398

What is the efficiency of a photovoltaic cell?

Back 398

D. The relative fraction of light that is converted to current

Front 399

What is the most common type of photovoltaic cell used for electrical power generation?

Back 399

B. Silicon

Front 400

Which of the following is the approximate open-circuit voltage produced by a fully-illuminated silicon photovoltaic cell?

Back 400

B. 0.5 V

Front 401

What absorbs the energy from light falling on a photovoltaic cell?

Back 401

C. Electrons

Front 402

Which of the following is a bistable circuit?

Back 402

C. A flip-flop

Front 403

How many output level changes are obtained for every two trigger pulses applied to the input of a T flip-flop circuit?

Back 403

C. Two

Front 404

Which of the following can divide the frequency of a pulse train by 2?

Back 404

B. A flip-flop

Front 405

How many flip-flops are required to divide a signal frequency by 4?

Back 405

B. 2

Front 406

Which of the following is a circuit that continuously alternates between two states without an external clock?

Back 406

D. Astable multivibrator

Front 407

What is a characteristic of a monostable multivibrator?

Back 407

A. It switches momentarily to the opposite binary state and then returns, after a set time, to its original state

Front 408

What logical operation does a NAND gate perform?

Back 408

D. It produces a logic "0" at its output only when all inputs are logic "1"

Front 409

What logical operation does an OR gate perform?

Back 409

A. It produces a logic "1" at its output if any or all inputs are logic "1"

Front 410

What logical operation is performed by a two-input exclusive NOR gate?

Back 410

C. It produces a logic "0" at its output if any single input is a logic "1"

Front 411

What is a truth table?

Back 411

C. A list of inputs and corresponding outputs for a digital device

Front 412

What is the name for logic which represents a logic "1" as a high voltage?

Back 412

D. Positive Logic

Front 413

What is the name for logic which represents a logic "0" as a high voltage?

Back 413

C. Negative logic

Front 414

What is an SR or RS flip-flop?

Back 414

B. A set/reset flip-flop whose output is low when R is high and S is low, high when S is high and R is low, and unchanged when both inputs are low

Front 415

What is a JK flip-flop?

Back 415

A. A flip-flop similar to an RS except that it toggles when both J and K are high

Front 416

What is a D flip-flop?

Back 416

A. A flip-flop whose output takes on the state of the D input when the clock signal transitions from low to high

Front 417

For what portion of a signal cycle does a Class AB amplifier operate?

Back 417

A. More than 180 degrees but less than 360 degrees

Front 418

What is a Class D amplifier?

Back 418

A. A type of amplifier that uses switching technology to achieve high efficiency

Front 419

Which of the following forms the output of a class D amplifier circuit?

Back 419

A. A low-pass filter to remove switching signal components

Front 420

Where on the load line of a Class A common emitter amplifier would bias normally be set?

Back 420

A. Approximately half-way between saturation and cutoff

Front 421

What can be done to prevent unwanted oscillations in an RF power amplifier?

Back 421

C. Install parasitic suppressors and/or neutralize the stage

Front 422

Which of the following amplifier types reduces or eliminates even-order harmonics?

Back 422

B. Push-pull

Front 423

Which of the following is a likely result when a Class C amplifier is used to amplify a single-sideband phone signal?

Back 423

D. Signal distortion and excessive bandwidth

Front 424

How can an RF power amplifier be neutralized?

Back 424

C. By feeding a 180-degree out-of-phase portion of the output back to the input

Front 425

Which of the following describes how the loading and tuning capacitors are to be adjusted when tuning a vacuum tube RF power amplifier that employs a pi-network output circuit?

Back 425

D. The tuning capacitor is adjusted for minimum plate current, while the loading capacitor is adjusted for maximum permissible plate current

Front 426

In Figure E7-1, what is the purpose of R1 and R2?

Back 426

B. Fixed bias

Front 427

In Figure E7-1, what is the purpose of R3?

Back 427

D. Self bias

Front 428

What type of circuit is shown in Figure E7-1?

Back 428

C. Common emitter amplifier

Front 429

In Figure E7-2, what is the purpose of R?

Back 429

A. Emitter load

Front 430

In Figure E7-2, what is the purpose of C2?

Back 430

A. Output coupling

Front 431

What is one way to prevent thermal runaway in a bipolar transistor amplifier?

Back 431

C. Use a resistor in series with the emitter

Front 432

What is the effect of intermodulation products in a linear power amplifier?

Back 432

A. Transmission of spurious signals

Front 433

Why are third-order intermodulation distortion products of particular concern in linear power amplifiers?

Back 433

A. Because they are relatively close in frequency to the desired signal

Front 434

Which of the following is a characteristic of a grounded-grid amplifier?

Back 434

C. Low input impedance

Front 435

What is a klystron?

Back 435

D. A VHF, UHF, or microwave vacuum tube that uses velocity modulation

Front 436

What is a parametric amplifier?

Back 436

B. A low-noise VHF or UHF amplifier relying on varying reactance for amplification

Front 437

Which of the following devices is generally best suited for UHF or microwave power amplifier applications?

Back 437

A. Field effect transistor

Front 438

How are the capacitors and inductors of a low-pass filter Pi-network arranged between the network's input and output?

Back 438

D. A capacitor is connected between the input and ground, another capacitor is connected between the output and ground, and an inductor is connected between input and output

Front 439

A T-network with series capacitors and a parallel shunt inductor has which of the following properties?

Back 439

C. It is a high-pass filter

Front 440

What advantage does a Pi-L-network have over a Pi-network for impedance matching between the final amplifier of a vacuum-tube transmitter and an antenna?

Back 440

A. Greater harmonic suppression

Front 441

How does an impedance-matching circuit transform a complex impedance to a resistive impedance?

Back 441

C. It cancels the reactive part of the impedance and changes the resistive part to a desired value

Front 442

Which filter type is described as having ripple in the passband and a sharp cutoff?

Back 442

D. A Chebyshev filter

Front 443

What are the distinguishing features of an elliptical filter?

Back 443

C. Extremely sharp cutoff with one or more notches in the stop band

Front 444

What kind of filter would you use to attenuate an interfering carrier signal while receiving an SSB transmission?

Back 444

B. A notch filter

Front 445

What kind of digital signal processing audio filter might be used to remove unwanted noise from a received SSB signal?

Back 445

A. An adaptive filter

Front 446

What type of digital signal processing filter might be used to generate an SSB signal?

Back 446

C. A Hilbert-transform filter

Front 447

Which of the following filters would be the best choice for use in a 2 meter repeater duplexer?

Back 447

B. A cavity filter

Front 448

Which of the following is the common name for a filter network which is equivalent to two L networks connected back-to-back with the inductors in series and the capacitors in shunt at the input and output?

Back 448

D. Pi

Front 449

Which of the following describes a Pi-L network used for matching a vacuum-tube final amplifier to a 50-ohm unbalanced output?

Back 449

B. A Pi network with an additional series inductor on the output

Front 450

What is one advantage of a Pi matching network over an L matching network consisting of a single inductor and a single capacitor?

Back 450

A. The Q of Pi networks can be varied depending on the component values chosen

Front 451

Which of these modes is most affected by non-linear phase response in a receiver IF filter?

Back 451

C. Digital

Front 452

What is one characteristic of a linear electronic voltage regulator?

Back 452

D. The conduction of a control element is varied to maintain a constant output voltage

Front 453

What is one characteristic of a switching electronic voltage regulator?

Back 453

C. The control device's duty cycle is controlled to produce a constant average output voltage

Front 454

What device is typically used as a stable reference voltage in a linear voltage regulator?

Back 454

A. A Zener diode

Front 455

Which of the following types of linear voltage regulator usually make the most efficient use of the primary power source?

Back 455

B. A series regulator

Front 456

Which of the following types of linear voltage regulator places a constant load on the unregulated voltage source?

Back 456

D. A shunt regulator

Front 457

What is the purpose of Q1 in the circuit shown in Figure E7-3?

Back 457

C. It increases the current-handling capability of the regulator

Front 458

What is the purpose of C2 in the circuit shown in Figure E7-3?

Back 458

A. It bypasses hum around D1

Front 459

What type of circuit is shown in Figure E7-3?

Back 459

C. Linear voltage regulator

Front 460

What is the purpose of C1 in the circuit shown in Figure E7-3?

Back 460

D. It filters the supply voltage

Front 461

What is the purpose of C3 in the circuit shown in Figure E7-3?

Back 461

A. It prevents self-oscillation

Front 462

What is the purpose of R1 in the circuit shown in Figure E7-3?

Back 462

C. It supplies current to D1

Front 463

What is the purpose of R2 in the circuit shown in Figure E7-3?

Back 463

D. It provides a constant minimum load for Q1

Front 464

What is the purpose of D1 in the circuit shown in Figure E7-3?

Back 464

B. To provide a voltage reference

Front 465

What is one purpose of a "bleeder" resistor in a conventional (unregulated) power supply?

Back 465

C. To improve output voltage regulation

Front 466

What is the purpose of a "step-start" circuit in a high-voltage power supply?

Back 466

D. To allow the filter capacitors to charge gradually

Front 467

When several electrolytic filter capacitors are connected in series to increase the operating voltage of a power supply filter circuit, why should resistors be connected across each capacitor?

Back 467

D. All of these choices are correct

Front 468

What is the primary reason that a high-frequency inverter type high-voltage power supply can be both less expensive and lighter in weight than a conventional power supply?

Back 468

C. The high frequency inverter design uses much smaller transformers and filter components for an equivalent power output

Front 469

Which of the following can be used to generate FM phone emissions?

Back 469

B. A reactance modulator on the oscillator

Front 470

What is the function of a reactance modulator?

Back 470

D. To produce PM signals by using an electrically variable inductance or capacitance

Front 471

How does an analog phase modulator function?

Back 471

C. By varying the tuning of an amplifier tank circuit to produce PM signals

Front 472

What is one way a single-sideband phone signal can be generated?

Back 472

A. By using a balanced modulator followed by a filter

Front 473

What circuit is added to an FM transmitter to boost the higher audio frequencies?

Back 473

D. A pre-emphasis network

Front 474

Why is de-emphasis commonly used in FM communications receivers?

Back 474

A. For compatibility with transmitters using phase modulation

Front 475

What is meant by the term baseband in radio communications?

Back 475

B. The frequency components present in the modulating signal

Front 476

What are the principal frequencies that appear at the output of a mixer circuit?

Back 476

C. The two input frequencies along with their sum and difference frequencies

Front 477

What occurs when an excessive amount of signal energy reaches a mixer circuit?

Back 477

A. Spurious mixer products are generated

Front 478

How does a diode detector function?

Back 478

A. By rectification and filtering of RF signals

Front 479

Which of the following types of detector is well suited for demodulating SSB signals?

Back 479

C. Product detector

Front 480

What is a frequency discriminator stage in a FM receiver?

Back 480

D. A circuit for detecting FM signals

Front 481

Which of the following describes a common means of generating an SSB signal when using digital signal processing?

Back 481

D. The quadrature method

Front 482

What is meant by direct conversion when referring to a software defined receiver?

Back 482

C. Incoming RF is mixed to "baseband" for analog-to-digital conversion and subsequent processing

Front 483

What is the purpose of a prescaler circuit?

Back 483

D. It divides a higher frequency signal so a low-frequency counter can display the input frequency

Front 484

Which of the following would be used to reduce a signal's frequency by a factor of ten?

Back 484

B. A prescaler

Front 485

What is the function of a decade counter digital IC?

Back 485

A. It produces one output pulse for every ten input pulses

Front 486

What additional circuitry must be added to a 100-kHz crystal-controlled marker generator so as to provide markers at 50 and 25 kHz?

Back 486

C. Two flip-flops

Front 487

Which of the following is a technique for providing high stability oscillators needed for microwave transmission and reception?

Back 487

D. All of these choices are correct

Front 488

What is one purpose of a marker generator?

Back 488

C. To provide a means of calibrating a receiver's frequency settings

Front 489

What determines the accuracy of a frequency counter?

Back 489

A. The accuracy of the time base

Front 490

Which of the following is performed by a frequency counter?

Back 490

C. Counting the number of input pulses occurring within a specific period of time

Front 491

What is the purpose of a frequency counter?

Back 491

A. To provide a digital representation of the frequency of a signal

Front 492

What alternate method of determining frequency, other than by directly counting input pulses, is used by some counters?

Back 492

B. Period measurement plus mathematical computation

Front 493

What is an advantage of a period-measuring frequency counter over a direct-count type?

Back 493

C. It provides improved resolution of low-frequency signals within a comparable time period

Front 494

What primarily determines the gain and frequency characteristics of an op-amp RC active filter?

Back 494

B. The values of capacitors and resistors external to the op-amp

Front 495

What is the effect of ringing in a filter?

Back 495

D. Undesired oscillations added to the desired signal

Front 496

Which of the following is an advantage of using an op-amp instead of LC elements in an audio filter?

Back 496

D. Op-amps exhibit gain rather than insertion loss

Front 497

Which of the following is a type of capacitor best suited for use in high-stability op-amp RC active filter circuits?

Back 497

C. Polystyrene

Front 498

How can unwanted ringing and audio instability be prevented in a multi-section op-amp RC audio filter circuit?

Back 498

A. Restrict both gain and Q

Front 499

Which of the following is the most appropriate use of an op-amp active filter?

Back 499

D. As an audio filter in a receiver

Front 500

What magnitude of voltage gain can be expected from the circuit in Figure E7-4 when R1 is 10 ohms and RF is 470 ohms?

Back 500

C. 47

Front 501

How does the gain of an ideal operational amplifier vary with frequency?

Back 501

D. It does not vary with frequency

Front 502

What will be the output voltage of the circuit shown in Figure E7-4 if R1 is 1000 ohms, RF is 10,000 ohms, and 0.23 volts dc is applied to the input?

Back 502

D. -2.3 volts

Front 503

What absolute voltage gain can be expected from the circuit in Figure E7-4 when R1 is 1800 ohms and RF is 68 kilohms?

Back 503

C. 38

Front 504

What absolute voltage gain can be expected from the circuit in Figure E7-4 when R1 is 3300 ohms and RF is 47 kilohms?

Back 504

B. 14

Front 505

What is an integrated circuit operational amplifier?

Back 505

A. A high-gain, direct-coupled differential amplifier with very high input and very low output impedance

Front 506

What is meant by the term op-amp input-offset voltage?

Back 506

C. The differential input voltage needed to bring the open-loop output voltage to zero

Front 507

What is the typical input impedance of an integrated circuit op-amp?

Back 507

D. Very high

Front 508

What is the typical output impedance of an integrated circuit op-amp?

Back 508

A. Very low

Front 509

What are three oscillator circuits used in Amateur Radio equipment?

Back 509

D. Colpitts, Hartley and Pierce

Front 510

What condition must exist for a circuit to oscillate?

Back 510

C. It must have positive feedback with a gain greater than 1

Front 511

How is positive feedback supplied in a Hartley oscillator?

Back 511

A. Through a tapped coil

Front 512

How is positive feedback supplied in a Colpitts oscillator?

Back 512

C. Through a capacitive divider

Front 513

How is positive feedback supplied in a Pierce oscillator?

Back 513

D. Through a quartz crystal

Front 514

Which of the following oscillator circuits are commonly used in VFOs?

Back 514

B. Colpitts and Hartley

Front 515

What is a magnetron oscillator?

Back 515

D. A reference standard oscillator in which the oscillations are synchronized by magnetic coupling to a rubidium gas tube

Front 516

What is a Gunn diode oscillator?

Back 516

A. An oscillator based on the negative resistance properties of properly-doped semiconductors

Front 517

What type of frequency synthesizer circuit uses a phase accumulator, lookup table, digital to analog converter and a low-pass anti-alias filter?

Back 517

A. A direct digital synthesizer

Front 518

What information is contained in the lookup table of a direct digital frequency synthesizer?

Back 518

B. The amplitude values that represent a sine-wave output

Front 519

What are the major spectral impurity components of direct digital synthesizers?

Back 519

C. Spurious signals at discrete frequencies

Front 520

Which of the following is a principal component of a direct digital synthesizer (DDS)?

Back 520

D. Phase accumulator

Front 521

What is the capture range of a phase-locked loop circuit?

Back 521

A. The frequency range over which the circuit can lock

Front 522

What is a phase-locked loop circuit?

Back 522

C. An electronic servo loop consisting of a phase detector, a low-pass filter, a voltage-controlled oscillator, and a stable reference oscillator

Front 523

Which of these functions can be performed by a phase-locked loop?

Back 523

D. Frequency synthesis, FM demodulation

Front 524

Why is the short-term stability of the reference oscillator important in the design of a phase locked loop (PLL) frequency synthesizer?

Back 524

B. Any phase variations in the reference oscillator signal will produce phase noise in the synthesizer output

Front 525

Why is a phase-locked loop often used as part of a variable frequency synthesizer for receivers and transmitters?

Back 525

C. It makes it possible for a VFO to have the same degree of frequency stability as a crystal oscillator

Front 526

What are the major spectral impurity components of phase-locked loop synthesizers?

Back 526

A. Phase noise

Front 527

What type of wave is made up of a sine wave plus all of its odd harmonics?

Back 527

A. A square wave

Front 528

What type of wave has a rise time significantly faster than its fall time (or vice versa)?

Back 528

C. A sawtooth wave

Front 529

What type of wave is made up of sine waves of a given fundamental frequency plus all its harmonics?

Back 529

A. A sawtooth wave

Front 530

What is equivalent to the root-mean-square value of an AC voltage?

Back 530

C. The DC voltage causing the same amount of heating in a resistor as the corresponding RMS AC voltage

Front 531

What would be the most accurate way of measuring the RMS voltage of a complex waveform?

Back 531

D. By measuring the heating effect in a known resistor

Front 532

What is the approximate ratio of PEP-to-average power in a typical single-sideband phone signal?

Back 532

A. 2.5 to 1

Front 533

What determines the PEP-to-average power ratio of a single-sideband phone signal?

Back 533

B. The characteristics of the modulating signal

Front 534

What is the period of a wave?

Back 534

A. The time required to complete one cycle

Front 535

What type of waveform is produced by human speech?

Back 535

C. Irregular

Front 536

Which of the following is a distinguishing characteristic of a pulse waveform?

Back 536

B. Narrow bursts of energy separated by periods of no signal

Front 537

What is one use for a pulse modulated signal?

Back 537

D. Digital data transmission

Front 538

What type of information can be conveyed using digital waveforms?

Back 538

D. All of these choices are correct

Front 539

What is an advantage of using digital signals instead of analog signals to convey the same information?

Back 539

C. Digital signals can be regenerated multiple times without error

Front 540

Which of these methods is commonly used to convert analog signals to digital signals?

Back 540

A. Sequential sampling

Front 541

What would the waveform of a stream of digital data bits look like on a conventional oscilloscope?

Back 541

B. A series of pulses with varying patterns

Front 542

What is the term for the ratio between the frequency deviation of an RF carrier wave, and the modulating frequency of its corresponding FM-phone signal?

Back 542

D. Modulation index

Front 543

How does the modulation index of a phase-modulated emission vary with RF carrier frequency (the modulated frequency)?

Back 543

D. It does not depend on the RF carrier frequency

Front 544

What is the modulation index of an FM-phone signal having a maximum frequency deviation of 3000 Hz either side of the carrier frequency, when the modulating frequency is 1000 Hz?

Back 544

A. 3

Front 545

What is the modulation index of an FM-phone signal having a maximum carrier deviation of plus or minus 6 kHz when modulated with a 2-kHz modulating frequency?

Back 545

B. 3

Front 546

What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus-or-minus 5 kHz when the maximum modulation frequency is 3 kHz?

Back 546

D. 1.67

Front 547

What is the deviation ratio of an FM-phone signal having a maximum frequency swing of plus or minus 7.5 kHz when the maximum modulation frequency is 3.5 kHz?

Back 547

A. 2.14

Front 548

When using a pulse-width modulation system, why is the transmitter's peak power greater than its average power?

Back 548

A. The signal duty cycle is less than 100%

Front 549

What parameter does the modulating signal vary in a pulse-position modulation system?

Back 549

D. The time at which each pulse occurs

Front 550

What is meant by deviation ratio?

Back 550

B. The ratio of the maximum carrier frequency deviation to the highest audio modulating frequency

Front 551

Which of these methods can be used to combine several separate analog information streams into a single analog radio frequency signal?

Back 551

C. Frequency division multiplexing

Front 552

Which of the following describes frequency division multiplexing?

Back 552

B. Two or more information streams are merged into a "baseband", which then modulates the transmitter

Front 553

What is digital time division multiplexing?

Back 553

B. Two or more signals are arranged to share discrete time slots of a data transmission

Front 554

Which one of the following digital codes consists of elements having unequal length?

Back 554

D. Morse code

Front 555

What are some of the differences between the Baudot digital code and ASCII?

Back 555

B. Baudot uses five data bits per character, ASCII uses seven or eight; Baudot uses two characters as shift codes, ASCII has no shift code

Front 556

What is one advantage of using the ASCII code for data communications?

Back 556

C. It is possible to transmit both upper and lower case text

Front 557

What technique is used to minimize the bandwidth requirements of a PSK31 signal?

Back 557

C. Use of sinusoidal data pulses

Front 558

What is the necessary bandwidth of a 13-WPM international Morse code transmission?

Back 558

C. Approximately 52 Hz

Front 559

What is the necessary bandwidth of a 170-hertz shift, 300-baud ASCII transmission?

Back 559

C. 0.5 kHz

Front 560

What is the necessary bandwidth of a 4800-Hz frequency shift, 9600-baud ASCII FM transmission?

Back 560

A. 15.36 kHz

Front 561

What term describes a wide-bandwidth communications system in which the transmitted carrier frequency varies according to some predetermined sequence?

Back 561

D. Spread-spectrum communication

Front 562

Which of these techniques causes a digital signal to appear as wide-band noise to a conventional receiver?

Back 562

A. Spread-spectrum

Front 563

What spread-spectrum communications technique alters the center frequency of a conventional carrier many times per second in accordance with a pseudo-random list of channels?

Back 563

A. Frequency hopping

Front 564

What spread-spectrum communications technique uses a high speed binary bit stream to shift the phase of an RF carrier?

Back 564

B. Direct sequence

Front 565

What is the advantage of including a parity bit with an ASCII character stream?

Back 565

D. Some types of errors can be detected

Front 566

What is one advantage of using JT-65 coding?

Back 566

B. The ability to decode signals which have a very low signal to noise ratio

Front 567

Which of the following is the easiest voltage amplitude parameter to measure when viewing a pure sine wave signal on an analog oscilloscope?

Back 567

A. Peak-to-peak voltage

Front 568

What is the relationship between the peak-to-peak voltage and the peak voltage amplitude of a symmetrical waveform?

Back 568

B. 2:1

Front 569

What input-amplitude parameter is valuable in evaluating the signal-handling capability of a Class A amplifier?

Back 569

A. Peak voltage

Front 570

What is the PEP output of a transmitter that develops a peak voltage of 30 volts into a 50-ohm load?

Back 570

B. 9 watts

Front 571

If an RMS-reading AC voltmeter reads 65 volts on a sinusoidal waveform, what is the peak-to-peak voltage?

Back 571

D. 184 volts

Front 572

What is the advantage of using a peak-reading wattmeter to monitor the output of a SSB phone transmitter?

Back 572

B. It gives a more accurate display of the PEP output when modulation is present

Front 573

What is an electromagnetic wave?

Back 573

C. A wave consisting of an electric field and a magnetic field oscillating at right angles to each other

Front 574

Which of the following best describes electromagnetic waves traveling in free space?

Back 574

D. Changing electric and magnetic fields propagate the energy

Front 575

What is meant by circularly polarized electromagnetic waves?

Back 575

B. Waves with a rotating electric field

Front 576

What type of meter should be used to monitor the output signal of a voice-modulated single-sideband transmitter to ensure you do not exceed the maximum allowable power?

Back 576

D. A peak-reading wattmeter

Front 577

What is the average power dissipated by a 50-ohm resistive load during one complete RF cycle having a peak voltage of 35 volts?

Back 577

A. 12.2 watts

Front 578

What is the peak voltage of a sinusoidal waveform if an RMS-reading voltmeter reads 34 volts?

Back 578

D. 48 volts

Front 579

Which of the following is a typical value for the peak voltage at a standard U.S. household electrical outlet?

Back 579

B. 170 volts

Front 580

Which of the following is a typical value for the peak-to-peak voltage at a standard U.S. household electrical outlet?

Back 580

C. 340 volts

Front 581

Which of the following is a typical value for the RMS voltage at a standard U.S. household electrical power outlet?

Back 581

A. 120V AC

Front 582

What is the RMS value of a 340-volt peak-to-peak pure sine wave?

Back 582

A. 120V AC

Front 583

Which of the following describes an isotropic antenna?

Back 583

C. A theoretical antenna used as a reference for antenna gain

Front 584

How much gain does a 1/2-wavelength dipole in free space have compared to an isotropic antenna?

Back 584

B. 2.15 dB

Front 585

Which of the following antennas has no gain in any direction?

Back 585

D. Isotropic antenna

Front 586

Why would one need to know the feed point impedance of an antenna?

Back 586

A. To match impedances in order to minimize standing wave ratio on the transmission line

Front 587

Which of the following factors may affect the feed point impedance of an antenna?

Back 587

B. Antenna height, conductor length/diameter ratio and location of nearby conductive objects

Front 588

What is included in the total resistance of an antenna system?

Back 588

D. Radiation resistance plus ohmic resistance

Front 589

What is a folded dipole antenna?

Back 589

C. A dipole constructed from one wavelength of wire forming a very thin loop

Front 590

What is meant by antenna gain?

Back 590

A. The ratio relating the radiated signal strength of an antenna in the direction of maximum radiation to that of a reference antenna

Front 591

What is meant by antenna bandwidth?

Back 591

B. The frequency range over which an antenna satisfies a performance requirement

Front 592

How is antenna efficiency calculated?

Back 592

B. (radiation resistance / total resistance) x 100%

Front 593

Which of the following choices is a way to improve the efficiency of a ground-mounted quarter-wave vertical antenna?

Back 593

A. Install a good radial system

Front 594

Which of the following factors determines ground losses for a ground-mounted vertical antenna operating in the 3-30 MHz range?

Back 594

C. Soil conductivity

Front 595

How much gain does an antenna have compared to a 1/2-wavelength dipole when it has 6 dB gain over an isotropic antenna?

Back 595

A. 3.85 dB

Front 596

How much gain does an antenna have compared to a 1/2-wavelength dipole when it has 12 dB gain over an isotropic antenna?

Back 596

B. 9.85 dB

Front 597

What is meant by the radiation resistance of an antenna?

Back 597

C. The value of a resistance that would dissipate the same amount of power as that radiated from an antenna

Front 598

In the antenna radiation pattern shown in Figure E9-1, what is the 3-dB beamwidth?

Back 598

B. 50 degrees

Front 599

In the antenna radiation pattern shown in Figure E9-1, what is the front-to-back ratio?

Back 599

B. 18 dB

Front 600

In the antenna radiation pattern shown in Figure E9-1, what is the front-to-side ratio?

Back 600

B. 14 dB

Front 601

What may occur when a directional antenna is operated at different frequencies within the band for which it was designed?

Back 601

D. The gain may change depending on frequency

Front 602

What usually occurs if a Yagi antenna is designed solely for maximum forward gain?

Back 602

B. The front-to-back ratio decreases

Front 603

If the boom of a Yagi antenna is lengthened and the elements are properly retuned, what usually occurs?

Back 603

A. The gain increases

Front 604

How does the total amount of radiation emitted by a directional gain antenna compare with the total amount of radiation emitted from an isotropic antenna, assuming each is driven by the same amount of power?

Back 604

C. They are the same

Front 605

How can the approximate beamwidth in a given plane of a directional antenna be determined?

Back 605

A. Note the two points where the signal strength of the antenna is 3 dB less than maximum and compute the angular difference

Front 606

What type of computer program technique is commonly used for modeling antennas?

Back 606

B. Method of Moments

Front 607

What is the principle of a Method of Moments analysis?

Back 607

A. A wire is modeled as a series of segments, each having a uniform value of current

Front 608

What is a disadvantage of decreasing the number of wire segments in an antenna model below the guideline of 10 segments per half-wavelength?

Back 608

C. The computed feed point impedance may be incorrect

Front 609

What is the far-field of an antenna?

Back 609

D. The region where the shape of the antenna pattern is independent of distance

Front 610

What does the abbreviation NEC stand for when applied to antenna modeling programs?

Back 610

B. Numerical Electromagnetics Code

Front 611

What type of information can be obtained by submitting the details of a proposed new antenna to a modeling program?

Back 611

D. All of these choices are correct

Front 612

What is the radiation pattern of two 1/4-wavelength vertical antennas spaced 1/2-wavelength apart and fed 180 degrees out of phase?

Back 612

D. A figure-8 oriented along the axis of the array

Front 613

What is the radiation pattern of two 1/4-wavelength vertical antennas spaced 1/4-wavelength apart and fed 90 degrees out of phase?

Back 613

A. A cardioid

Front 614

What is the radiation pattern of two 1/4-wavelength vertical antennas spaced 1/2-wavelength apart and fed in phase?

Back 614

C. A Figure-8 broadside to the axis of the array

Front 615

Which of the following describes a basic unterminated rhombic antenna?

Back 615

B. Bidirectional; four-sides, each side one or more wavelengths long; open at the end opposite the transmission line connection

Front 616

What are the disadvantages of a terminated rhombic antenna for the HF bands?

Back 616

C. The antenna requires a large physical area and 4 separate supports

Front 617

What is the effect of a terminating resistor on a rhombic antenna?

Back 617

B. It changes the radiation pattern from bidirectional to unidirectional

Front 618

What type of antenna pattern over real ground is shown in Figure E9-2?

Back 618

A. Elevation

Front 619

What is the elevation angle of peak response in the antenna radiation pattern shown in Figure E9-2?

Back 619

C. 7.5 degrees

Front 620

What is the front-to-back ratio of the radiation pattern shown in Figure E9-2?

Back 620

B. 28 dB

Front 621

How many elevation lobes appear in the forward direction of the antenna radiation pattern shown in Figure E9-2?

Back 621

A. 4

Front 622

How is the far-field elevation pattern of a vertically polarized antenna affected by being mounted over seawater versus rocky ground?

Back 622

D. The low-angle radiation increases

Front 623

When constructing a Beverage antenna, which of the following factors should be included in the design to achieve good performance at the desired frequency?

Back 623

D. It should be one or more wavelengths long

Front 624

What is the main effect of placing a vertical antenna over an imperfect ground?

Back 624

C. It reduces low-angle radiation

Front 625

How does the gain of an ideal parabolic dish antenna change when the operating frequency is doubled?

Back 625

C. Gain increases by 6 dB

Front 626

How can linearly polarized Yagi antennas be used to produce circular polarization?

Back 626

C. Arrange two Yagis perpendicular to each other with the driven elements at the same point on the boom and fed 90 degrees out of phase

Front 627

How does the beamwidth of an antenna vary as the gain is increased?

Back 627

D. It decreases

Front 628

Why is it desirable for a ground-mounted satellite communications antenna system to be able to move in both azimuth and elevation?

Back 628

A. In order to track the satellite as it orbits the Earth

Front 629

Where should a high-Q loading coil be placed to minimize losses in a shortened vertical antenna?

Back 629

A. Near the center of the vertical radiator

Front 630

Why should an HF mobile antenna loading coil have a high ratio of reactance to resistance?

Back 630

C. To minimize losses

Front 631

What is a disadvantage of using a multiband trapped antenna?

Back 631

A. It might radiate harmonics

Front 632

What happens to the bandwidth of an antenna as it is shortened through the use of loading coils?

Back 632

B. It is decreased

Front 633

What is an advantage of using top loading in a shortened HF vertical antenna?

Back 633

D. Improved radiation efficiency

Front 634

What is the approximate feed point impedance at the center of a two-wire folded dipole antenna?

Back 634

A. 300 ohms

Front 635

What is the function of a loading coil as used with an HF mobile antenna?

Back 635

D. To cancel capacitive reactance

Front 636

What is one advantage of using a trapped antenna?

Back 636

D. It may be used for multiband operation

Front 637

What happens to feed point impedance at the base of a fixed-length HF mobile antenna as the frequency of operation is lowered?

Back 637

B. The radiation resistance decreases and the capacitive reactance increases

Front 638

Which of the following types of conductor would be best for minimizing losses in a station's RF ground system?

Back 638

B. A wide flat copper strap

Front 639

Which of the following would provide the best RF ground for your station?

Back 639

C. An electrically-short connection to 3 or 4 interconnected ground rods driven into the Earth

Front 640

What system matches a high-impedance transmission line to a lower impedance antenna by connecting the line to the driven element in two places spaced a fraction of a wavelength each side of element center?

Back 640

B. The delta matching system

Front 641

What is the name of an antenna matching system that matches an unbalanced feed line to an antenna by feeding the driven element both at the center of the element and at a fraction of a wavelength to one side of center?

Back 641

A. The gamma match

Front 642

What is the name of the matching system that uses a section of transmission line connected in parallel with the feed line at or near the feed point?

Back 642

D. The stub match

Front 643

What is the purpose of the series capacitor in a gamma-type antenna matching network?

Back 643

B. To cancel the inductive reactance of the matching network

Front 644

How must the driven element in a 3-element Yagi be tuned to use a hairpin matching system?

Back 644

A. The driven element reactance must be capacitive

Front 645

What is the equivalent lumped-constant network for a hairpin matching system on a

Back 645

B. Pi-L network

Front 646

What term best describes the interactions at the load end of a mismatched transmission line?

Back 646

B. Reflection coefficient

Front 647

Which of the following measurements is characteristic of a mismatched transmission line?

Back 647

D. An SWR greater than 1:1

Front 648

Which of these matching systems is an effective method of connecting a 50-ohm coaxial cable feed line to a grounded tower so it can be used as a vertical antenna?

Back 648

C. Gamma match

Front 649

Which of these choices is an effective way to match an antenna with a 100-ohm feed point impedance to a 50-ohm coaxial cable feed line?

Back 649

C. Insert a 1/4-wavelength piece of 75-ohm coaxial cable transmission line in series between the antenna terminals and the 50-ohm feed cable

Front 650

What is an effective way of matching a feed line to a VHF or UHF antenna when the impedances of both the antenna and feed line are unknown?

Back 650

B. Use the universal stub matching technique

Front 651

What is the primary purpose of a phasing line when used with an antenna having multiple driven elements?

Back 651

A. It ensures that each driven element operates in concert with the others to create the desired antenna pattern

Front 652

What is the purpose of a Wilkinson divider?

Back 652

C. It divides power equally among multiple loads while preventing changes in one load from disturbing power flow to the others

Front 653

What is the velocity factor of a transmission line?

Back 653

D. The velocity of the wave in the transmission line divided by the velocity of light in a vacuum

Front 654

Which of the following determines the velocity factor of a transmission line?

Back 654

C. Dielectric materials used in the line

Front 655

Why is the physical length of a coaxial cable transmission line shorter than its electrical length?

Back 655

D. Electrical signals move more slowly in a coaxial cable than in air

Front 656

What is the typical velocity factor for a coaxial cable with solid polyethylene dielectric?

Back 656

B. 0.66

Front 657

What is the approximate physical length of a solid polyethylene dielectric coaxial transmission line that is electrically one-quarter wavelength long at 14.1 MHz?

Back 657

C. 3.5 meters

Front 658

What is the approximate physical length of an air-insulated, parallel conductor transmission line that is electrically one-half wavelength long at 14.10 MHz?

Back 658

C. 10 meters

Front 659

How does ladder line compare to small-diameter coaxial cable such as RG-58 at 50 MHz?

Back 659

A. Lower loss

Front 660

What is the term for the ratio of the actual speed at which a signal travels through a transmission line to the speed of light in a vacuum?

Back 660

A. Velocity factor

Front 661

What is the approximate physical length of a solid polyethylene dielectric coaxial transmission line that is electrically one-quarter wavelength long at 7.2 MHz?

Back 661

B. 6.9 meters

Front 662

What impedance does a 1/8-wavelength transmission line present to a generator when the line is shorted at the far end?

Back 662

C. An inductive reactance

Front 663

What impedance does a 1/8-wavelength transmission line present to a generator when the line is open at the far end?

Back 663

C. A capacitive reactance

Front 664

What impedance does a 1/4-wavelength transmission line present to a generator when the line is open at the far end?

Back 664

D. Very low impedance

Front 665

What impedance does a 1/4-wavelength transmission line present to a generator when the line is shorted at the far end?

Back 665

A. Very high impedance

Front 666

What impedance does a 1/2-wavelength transmission line present to a generator when the line is shorted at the far end?

Back 666

B. Very low impedance

Front 667

What impedance does a 1/2-wavelength transmission line present to a generator when the line is open at the far end?

Back 667

A. Very high impedance

Front 668

Which of the following is a significant difference between foam-dielectric coaxial cable and solid-dielectric cable, assuming all other parameters are the same?

Back 668

D. All of these choices are correct

Front 669

Which of the following can be calculated using a Smith chart?

Back 669

A. Impedance along transmission lines

Front 670

What type of coordinate system is used in a Smith chart?

Back 670

B. Resistance circles and reactance arcs

Front 671

Which of the following is often determined using a Smith chart?

Back 671

C. Impedance and SWR values in transmission lines

Front 672

What are the two families of circles and arcs that make up a Smith chart?

Back 672

C. Resistance and reactance

Front 673

What type of chart is shown in Figure E9-3?

Back 673

A. Smith chart

Front 674

On the Smith chart shown in Figure E9-3, what is the name for the large outer circle on which the reactance arcs terminate?

Back 674

B. Reactance axis

Front 675

On the Smith chart shown in Figure E9-3, what is the only straight line shown?

Back 675

D. The resistance axis

Front 676

What is the process of normalization with regard to a Smith chart?

Back 676

C. Reassigning impedance values with regard to the prime center

Front 677

What third family of circles is often added to a Smith chart during the process of solving problems?

Back 677

A. Standing-wave ratio circles

Front 678

What do the arcs on a Smith chart represent?

Back 678

D. Points with constant reactance

Front 679

How are the wavelength scales on a Smith chart calibrated?

Back 679

B. In fractions of transmission line electrical wavelength

Front 680

What is the effective radiated power relative to a dipole of a repeater station with 150 watts transmitter power output, 2-dB feed line loss, 2.2-dB duplexer loss and 7-dBd antenna gain?

Back 680

D. 286 watts

Front 681

What is the effective radiated power relative to a dipole of a repeater station with 200 watts transmitter power output, 4-dB feed line loss, 3.2-dB duplexer loss, 0.8-dB circulator loss and 10-dBd antenna gain?

Back 681

A. 317 watts

Front 682

What is the effective isotropic radiated power of a repeater station with 200 watts transmitter power output, 2-dB feed line loss, 2.8-dB duplexer loss, 1.2-dB circulator loss and 7-dBi antenna gain?

Back 682

B. 252 watts

Front 683

What term describes station output, including the transmitter, antenna and everything in between, when considering transmitter power and system gains and losses?

Back 683

C. Effective radiated power

Front 684

What is the main drawback of a wire-loop antenna for direction finding?

Back 684

A. It has a bidirectional pattern

Front 685

What is the triangulation method of direction finding?

Back 685

C. Antenna headings from several different receiving locations are used to locate the signal source

Front 686

Why is it advisable to use an RF attenuator on a receiver being used for direction finding?

Back 686

D. It prevents receiver overload which could make it difficult to determine peaks or nulls

Front 687

What is the function of a sense antenna?

Back 687

A. It modifies the pattern of a DF antenna array to provide a null in one direction

Front 688

Which of the following describes the construction of a receiving loop antenna?

Back 688

C. One or more turns of wire wound in the shape of a large open coil

Front 689

How can the output voltage of a multi-turn receiving loop antenna be increased?

Back 689

D. By increasing either the number of wire turns in the loop or the area of the loop structure or both

Front 690

What characteristic of a cardioid-pattern antenna is useful for direction finding?

Back 690

B. A very sharp single null

Front 691

What is an advantage of using a shielded loop antenna for direction finding?

Back 691

B. It is electro-statically balanced against ground, giving better nulls

Front 692

What, if any, are the differences between the radiation produced by radioactive materials and the electromagnetic energy radiated by an antenna?

Back 692

C. Radioactive materials emit ionizing radiation, while RF signals have less energy and can only cause heating

Front 693

When evaluating RF exposure levels from your station at a neighbor's home, what must you do?

Back 693

B. Make sure signals from your station are less than the uncontrolled MPE limits

Front 694

Which of the following would be a practical way to estimate whether the RF fields produced by an amateur radio station are within permissible MPE limits?

Back 694

C. Use an antenna modeling program to calculate field strength at accessible locations

Front 695

When evaluating a site with multiple transmitters operating at the same time, the operators and licensees of which transmitters are responsible for mitigating over-exposure situations?

Back 695

C. Each transmitter that produces 5% or more of its MPE exposure limit at accessible locations

Front 696

What is one of the potential hazards of using microwaves in the amateur radio bands?

Back 696

B. The high gain antennas commonly used can result in high exposure levels

Front 697

Why are there separate electric (E) and magnetic (H) field MPE limits?

Back 697

D. All of these choices are correct

Front 698

How may dangerous levels of carbon monoxide from an emergency generator be detected?

Back 698

B. Only with a carbon monoxide detector

Front 699

What does SAR measure?

Back 699

C. The rate at which RF energy is absorbed by the body

Front 700

Which insulating material commonly used as a thermal conductor for some types of electronic devices is extremely toxic if broken or crushed and the particles are accidentally inhaled?

Back 700

C. Beryllium Oxide

Front 701

What material found in some electronic components such as high-voltage capacitors and transformers is considered toxic?

Back 701

A. Polychlorinated biphenyls

Front 702

Which of the following injuries can result from using high-power UHF or microwave transmitters?

Back 702

C. Localized heating of the body from RF exposure in excess of the MPE limits