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110 Cards in this Set

  • Front
  • Back
220.1 A signal generator is primarily used to troubleshoot what type of circuit?
Frequency sensitive or tuned circuit.
220.2 What range of frequencies does the audio signal generator provide?
From 20hz to 20 Khz
220.3 What range of frequuencies does the radio frequency signal generator provide?
From 10kHz to 10 GHz
220.4 What do you use to match the input impedance of a circuit under test?
An attenuator
220.5 What are the major components of a basic signal generator?
Power supply, one or more oscillators, one or more amplifiers, and an output control.
220.6 Why are voltage regulation circuits necessary?
To ensure stability of the oscillator in generators deriving power from 115-volt AC sources.
220.7 What element of a resistance capacitance oscillator in a commercial signal generator is used as a variable element?
220.8 How do you conduct a distortion comparison in transmitters and receivers using an audio signal generator?
An audio generator can provid a modulation reference signal for a transmitter to send information to a remote receiver. The receiver recovers the transmitted signal (modulation reference) and compares it with the original for any noise distortion.
221.1 What is the frequency range of the HP 8640B radio frequency signal generator?
500 kHz to 512 MHz (450 kHz to 550 Mhz with over-range.
221.2 What extends the HP 8640B range from 20 Hz to ultra high frequencies?
A variable audo oscillator can extend the ouput range of the generator down to 20 Hz and a doubler can extend it to 11,000 MHz. This together with a calibrated output and modulation, permits complete radio frequency and intermediate frequency performance tests on virtually any type of high frequency, very high frequency, or ultra high frequency receiver.
221.3 What is the function of the modulator?
To produce a signal that can be set accurately in frequency at any point within the range of the generator.
221.4 What is the function of the modulator?
To produce an audio modulating signal to superimpose on the radio frequency signal produced in the oscillator.
221.5 What types of modulated signals are pssible with the radio frequency generator?
Either sine waves, square waves, or pulses of varying duration.
221.6 What does the ouput circuit of the radio frequency signal usually contain, and what are their functions?
A calibrated attenuator and an output level meter. The attenuator lets you select the amount of output required. The output level meter provides an indication and permits control of the generator ouput voltage.
221.7 List some applications of the radio frequency generator.
1) Verify transmission within designated frequency ranges by comparing transmitter outputs with known radio frequencies.
2) Align a receiver by injecting the system with range-standard modulated radio frequency.
3) Check transmission lines and antenna systems for proper operation.
222.1 What is the output impedance available at the HP 3325B's fron and rear panel output jacks
50 ohms
222.2 List the output frequency ranges the HP3325B can produce for its different output signal types.
Sine wave - 1 MicroHz to 20Mhz
Square waves - 1 MicroHz to 10 Mhz
Triangle and positive/negative Ramps - 1 MicroHz to 10 kHz
222.3 Describe the functions of the arrow keys in the Modify keypad.
The horizontal arrow keys select the digital to modify, and the vertical arrows increment or decrement the digit.
222.4 What internally generated modulating signals can the HP 3325B use to amplitude modulat the main signal?
A 10 Khz sine wave or a 2 kHz square wave
222.5 What is the HP 3325B's Synch output signal generally used for?
223.1 The decibel is part of what larger unit of measure?
223.2 A power ration of 10,000:1 can be represented by how many bels?
223.3 What's the attenuation ratio of a device if the input power is 40 W and the output power is 40 mW?
223.4 Calculate the output of 40 dB attenuator with a 550 watt input
55 mW
223.5 Whats the attenuation ratio of the attenuator in question 4?
223.6 What's the most commonly used industry standard power reference level?
The 1-milliwat standard
223.7 How is the answer to # 6 expressed?
As decibels referenced to a 1-milliwatt standard or dBm
223.8 Rewrite thise sentences so thy use the term dB correctly.
a)This TWT has 25 dB of output power
b) The final amp is pumping out a 30 dB package
a) This TWT has a power gain of 25 dB;
b) The final amp is pumping out a package that's 30 dB more than its input
223.9 What will every 3 dB increase in gain do to the power level?
Roughly double it
223.10 How many dB of gain does an amplifier have if ther's 10 watts in and 80 watts out?
There is a gain of about 9 dB
223.11 You have installed an in line 3 dB attenuator between a power source and the power sensor of a power meter. How will this affect the power level displayed by the power meter?
It will cut it in half
223.12 What two power characteristics are reflected by the term dBm?
Gain and power level
223.13 How much do the terms dB and dBm differ?
Because dBm is always referenced to a 1 - milliwatt standard, it can be used to reflect a power level, in addition to gain or loss. The term dB can't reflect a power level; instead, it can only reflect gain or loss because it's purely a ratio
223.14 How much more power is available at 6 dBm than 3 dBm?
Twice as much
223.15 What power levels are indicated by these measurments?
a) 2mW, b) 8mW, c) 16mW, d) 4096mW (approx 4.1 watts)
224.1 List at least three of the units that can be displayed by the HP 436A power meter.
Watts, milliwatts, microwatts, nanowatts, dBm, and relative dB
224.2 Briefly explain how to use the relateve power measurement mode for frequency response testing.
After the input is connected, press dB(REF) to lock in this frequency level as the reference, thne tune the transmitter to other frequencies and observe any changes up or down in the power level.
225.1 In its broadest sense, what does a power sensor do?
Operates as a transducer converting energy from one form into another
225.2 Name some of the older power meters.
Bolometer, calorimeters, thermistors, and thermocouples.
225.3 What are of the advantages of a diode detector over a thermistor mount?
Higher sensitivity, reduced noise, less frequency drift, and lower standing wave ratio.
225.4 How much more efficient is a detecting diode than a thermistor
About 3,000 times
225.5 What device dtermines the power measurement range of a power meter?
The power sensor
225.6 What must you do before you can use the power meter/power sensor system?
Calibrate them together as a system
225.7 Explain the calibration process.
connect the pwer sensor to the POWER REF OUTPUT, press POWER REF ON, and adjust the CAL ADJ until the display reads 1.000mW
225.8 Why shouldn't you twist a power sensor when you're installing it?
Twisting can damage the sensor's internal circuitry.
225.9 What must you use to protect the sensor if the radio frequency source is more powerful than the power can handle?
An in-line attenuator
225.10 What's a drawback to the power sensor's small size?
It's easily dropped, banged, or knocked around
225.11 What should you do with a power sensor if it has been dropped?
It should be sent to the test equipment calibration lab
226.1 What's the basic radio frequency power measurement?
Average power
226.2 What must you do before turning the HP 436A Power Meter on?
Make sure the line voltage setting on the back of the power meter matches the line voltage you're using.
226.3 After you've turned on the 436A what's the first task you need to do?
Zero the power sensor.
226.4 How much radio frequency input is allowed in zeroing the power sensor?
226.5 After you've zeroed the power sensor, what's the next step?
Calibrate the power sensor
226.6 What power measurement mode must you select to measure average power?
Either WATT or dBm.
226.7 What's a good use of the relative power measurement technique?
Troubleshooting stages of a piece of equipment.
226.8 In preparing to make a relative power measurement with the 436:, how do you store the referenced power level for later comparison?
By pressing the DB REF switch once.
226.9 Once you've stored the reference power level, what should the display read?
226.10 What happens when you press the dB REF swich a second time?
A new reference power level is stored in the 436A.
227.1 What is a major difference between the oscilloscope and the spectrum analyzer?
The oscilloscope displays frequency information in the time domain, wheras the spectrum analyzer displays frequency information in the frequency domain.
227.2 Describe how the spectrum analyzer displays information in the frequency domain?
By complex signals (i.e., signals composed of more thatn one frequency) that are separated into their frequency components, and the power level of each frequency is displayed.
227.3 What functions does the spectrum analyzer perform?
1. Locate and identify signals over a wide frequency spectrum
2. Magnify parts of the spectrum for detailed analysis with stable, calibrated sweeps and resolution.
227.3 What funcions does the spectrum analyzer perform?
1. Locate and identify signals over a wide frequency spectrum
2. Magnify parts of the spectrum for detailed analysis with stable, calibrated sweeps and resolution.
3. Minimize display clutter for spurious responses within itself.
4. Furnish wide dynamic range and flat frequency response
227.4 What advantage do the spectrum analyzer's sensitivity and wide dynamic range provide?
A way to measure low level modulation
227.5 List some uses of the spectrum analyzer.
1. Measure AM, FM, and pulsed radio frequency
2. Measure long and short term frequency stability
3. Measure parameters such as subcarrier oscillator outputs, channels of complex signas
4. Measure frequency drift during system warm up.
228.1 What frequency range does the Tektronix 496P spectrum analyzer cover?
From 1KHz to 1.8 GHz.
228.2 Which trigger control selection is best for general measurements?
Free running sweep, unless you need to trigger the sweep, as for pulse modulation measurements or technically directed measurements.
228.3 Which spectrum analyzer trigger control selection would you use to display an input signal that is not continuous?
Internal (INT)
228.4 What spectrum analyzer trigger mode would you use to observe a signal that depends on the occurrence of another signal?
External (EXT)
228.5 Which spectrum analyzer trigger control lets the sweep be triggered by the AC power source at a rate equal to the frequency of the power source?
228.6 What sweep control functions just as it does on an oscilloscope adjusting sweep rate.
228.7 Which spectrum analyzer sweep control do you select to run the sweep only once after triggering and must have a READY light indicaiton each time it is run?
Single sweep
228.8 How is sweep rate determined in MANUAL SCAN?
By the rate at which the MANUAL SCAN control is rotated
228.9 Which spectrum analyzer sweep control do you select to use an external signal to generate the sweep at a rate determined by the signal amplitude?
External (EXT)
228.10 Which spectrum analyzer FREQUENCY SCAN/DIV mode do you use to locate signals?
228.11 In the per division mode, which spectrum analyzer FREQUENCY SCAN/DIV control sets the center frequency?
228.12 An analyzer acts like an oscilloscope when the FREQ SPAN/DIV control is in which scan mode?
0 Hz
228.13 What is the purpose of the spectrum analyzer FREQUENCY control?
sets the midpoint (center) of the frequency range for display on the analyzer CRT.
228.14 Which spectrum analyzer control selects different frequency bands to be displayed?
228.15 If you decrease vertical display, i.e., dB/DIV, what is the effect on the vertical display range?
Reduces the amplitude.
228.16 In which vertical scale is the value of the bottom line on the CRT grid at 0 volts?
Linear (LIN)
228.17 In which vertical scale is the value of the bottom line on the CRT grid at 0 volts?
228.18 Using a spectrum analyzer, what will the signal amplitude be if you're in the LIN (linear) VERTICAL DISPLAY mode, the VERTICAL DISPLAY reads "5.00/mV," and ther is a signal peak six divisions above the CRT bottom line?
30 mV
228.19 In spectrum analyzers, to what does the term "optimum input level" refer?
To the largest input signal that a mixer will accommodate while maintaining ouput distortion products below a given level (specified by the manufacturer). It is usually a negative dB value.
228.20 In spectrum analyzers, to wht does the term maximum input level refer?
Indicate the damage level of the analyzer front end (mixer and attenuator). Two values are given for maximum input level: the damage level of the mixer and the of the attenuator.
228.21 What does a '>' symbol indicate, and what other indication also shows this condition?
It indicates an uncalibrated condition. When it's lit, the UNCAL light also indicates that the display amplitude has become "uncalibrated" (inaccurate).
228.22 What affect does decreasing the spectrum analyzer TIME/DIV have on sweep rate and the time the intermediate frequency filters have to respond to an input?
Increase sweep rat; decreaes intermediate frequency filter response time.
228.23 What combinations restores an uncalibrated display on the spectrum analyzer?
Increasing the RESOLUTION BANDWIDTH, increasing the TIME/DIV (reducing sweep rate), reducing mixes the SPAN/DIV, and removing video filtering.
229.1 What is the frequency range of an electronic frequency counter?
Low audio frequencies up to 550 Mhz. Some methods are available to extend the frequency range of counters to more than 20 Ghz.
229.3 What provides the time reference for the precise timing and where does this function take place?
A quartz-crysat oscillator inside the counter.
230.1 How is an electonic frequency counter used in communication-electronics?
For verifying transmitter and bit clock frequencies, as well as monitoring frequency modulation drift
230.2 What is a primary limitation of an electronic frequency counter?
It can't be used directly for receiver calibration, since it's a passive device (only measures) and doesn't produce signals (except for internal use).
230.2 What is a primary limitation of an electronic frequency counter?
It can't be used directly for receiver calibration, since it's a passive device (only measures) and doesn't produce signals (except for internal use).
230.3 What sections are in a frequency counter heterodyne unit?
A 1 MHz crystal oscillator, a clipper, and a series of frequency dividing circuits.
230.4 What is the advantage of using a Schmitt trigger in the input section of the frequency counter?
It produces a very sharp rectangular pulse desite teh shap of the signal at the input
230.5 What are the components in a frequency counter time base?
A 1 MHz crystal oscillator, a clipper, and a series of frequency dividing circuits.
230.6 How is the 1 MHz oscillator kept at a stable frequency?
It's maintained in a temperature compensated oven
230.7 What are the functions of the gating section?
To establish the duration of the counting interval to gate the input signal through to the decimal counting section and to drive the reset circuits, causing the counters to initiate a new cycle of operation.
230.8 What units are in the display section?
Five decimal counting units connected in cascade.
230.9 What is the maximum count the display section counter units will register?
99,999 counts derived from the signal being measured.
231.1 What kind of cable faults can a time domain reflectometer locate?
Splices, water in the cable, split pairs, and discontinuities or faults.
231.2 Describe the time domain reflectometer's operating principle.
The principle of operation for the time domain reflectometer is similar to that of radar. A pulse from the time domain reflectometer is applied to a cable under test. Any impedance changes in the cable cause a portion of that voltage or energy to be reflected back to the cable input.
231.3 Explain how cable fault information appears on the time domain reflectometer's CRT.
The CRT displays the pulse's progression from application to the cable on the left hand side of the display to its return at the right. From the display, one can determine the distance down the cable to wher the fault is and the type and severity of the fault.
231.4 Explain the purpose of the impedance selector buttons.
Used to select the input/output impedance of the time domain reflectometer. You can select 50 ohm, 75 ohm, 95 ohm, and 125 impedances.
231.5 Describe how you would connect a cable under test to the time domain reflectometer.
Do not connect live circuit cables to the input of the time domain reflectometer. Connect the cable under test to the cable connector on the front panel of the time domain reflectometer.
231.6 What do deflections (pips) indicate to the time domain reflectometer user?
The key signature factors to remember are upward deflections (pips) indicate high impedance mismatchs or opens and downward deflection (pips) indicate shorts or low impedance mismatches.
232.1 Describe the two operating modes used by the TD 9930.
REAL-TIME operation, reflections are amplified and displayed directly on the CRT for examination. In the AVG (AVERAGE) mode, the amplified signals are averaged to reduce noise, then stored as digital data.
232.3 What are the tests and measurements performed by the optical time domain reflectometer?
Cable acceptance testin; cable installation; end to end tests; fault location
232.4 What do we call this power that's reflected back?
232.5 How is the signal loss represented in on optical time domain reflectometer display?
The dB drop in backscatter between the two reflections is the signal loss within the fiber.
232.6 What index factor is the TD-9930 already programmed to accept?