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108 Cards in this Set

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601. What does "frequency accuracy" refer to when discussing transmitters?
Ability to maintain a constant output carrier
601. Name the four basic requirements needed to accomplish any type of modulation.
1. Rf carrier
2. Intellegence
3. Non linear device to heterodyne the reference and modulating signals
4. Ckt that contains filtering components to pass desired RF fx's
601. What does the modulation envelope represent?
Represents algebraic sum of the carrier and sidebands as it would appear
601. What three frequencies are contained in the modulated carrier wave?
Carrier, Upper, and Lower
Define "percent of modulation."
The amount of effect or change that the intellegence has on the carrier
What is the formula for Percent of Modulation?
emax - emin/emax + emin times 100
602. What is the formula for Percent of Modulation?
emax - emin/emax + emin times 100
emax of 50vrms emin of 5 Vrms what is the percent of mod?
81.8
602. What are the two results of overmodulation?
Causes distortion and Am bandwidth increases
Name the modules that make up the APC circuit
DC1, A10, A6
603. Name the modules that make up the APC circuit
DC1, A10, A6
603. What does the APC voltage do if the forward power gets too high?
Varies the gain to make it normal
603. State the purpose of the e/l relay when operating the transmitter in 10 watt mode?
Has no Purpose
604. Why does the UHF multiplier contain one more stage of amplification than that of the VHF version?
Because the fourth harmonic is weaker than the second
604. State the purpose of the transmitter's tune/operate switch
Protect the tunable filter during tuning operation
604. What happens if the VSWR exceeds 3:1?
The e/l relay is energized and we bypass the LPA to prevent damage
604. Why are we concerned with removing the RF from the E/L relay when it is energized?
To prevent the contacts from arcing
605. What is the pupose of the linear power amplifier?
To amplify from 10w to 50w
605. State the purpose of C1 and L1 in the A4 module (pwr amp)
Filter ripple out of 2000vdc
605. In the A5 module, what are the LPA FWD and RVS power sensor voltages used for? (pwr amp)
Develope APC voltage and detect vswr
605. State the purpose of the tune operate switch in the pwr amp
It decreases the exciter RF output to less than 10 watts out, and it prevents the E/L relay from energizing
606. What is a superheterodyne receiver
Uses the mixer to make intermediate fx
606. Why is it necessary for the RF amplifier section to isolate the local oscillator from the antenna?
If Antenna was connected directly to mixer part of oscillator, the signal could be radiated into space causing interference with other receivers
606. Define "image frequency."
Undesired signal that when mixed in the mixer produces the correct IF
606. What is the difference between a mixer circuit and a converter circuit?
The mixer requires two input signals-the radio frequency and the injection frequency. A converter has its own self contained oscillator and, thus, requires only one input signal-the radio fx
607. Define "demodulation"
Recovering intellegence from the modulated wave
607. Briefly state the requirements for any type of demodulation?
sensitivity
Nonlinearity
RF carrier signal
Filtering
607. What are the main drawbacks of using diode detectors?
No pwr gain, Selectivity is affected by loading of the tank
607. What factor determines the amount of amplification needed in the audio amplifier circuit?
The type of output device (headphones)
608. Which module in the AN/GRR-23 and the AN/GRR-24 performs the function of preselection?
Tunable filter (fl2)
608. Which module determines overall selectivity? (AN/GRR-23 AND 24)
Crystal filter (FL1)
608. What happens to the DC portion of the detector output? (AN/GRR-23 AND 24)
Applied to AGC section of the A3
609. In the UHF mixer/multiplier A2, to what frequency would Q1 be tuned if the oscillator synthesizer's output were 67.0 MHz
268 Multiply by 4
609. In the UHF mixer/multiplier A2, what frequency will the output of transistor Q8 pass with an operating frequency of 321 Mhz? (AN/GRR23 AND 24)
20.6 Always
In what section does most of the rx's amplification take place?
IF Amplifier
609. What is the purpose of the receiver's AGC circuit?
Provide constant audio output with varying RF input
609. What is the purpose of the receiver's squelch circuit?
To pass audio at the antenna or to block it
610. State the purpose of HAVE QUICK radio's
To prevent hostiles from Jamming the radio's
610. What is the purpose of WOD and TOD?
To get the same frequencies at the same time
610. Why isn't HAVE QUICK considered a means of secure communications?
It doesn't use encryption and enemy could tune 7000 receiver's
610. List two differences between HQ1 and HQ2
Have quick one allows one word to be loaded at a time

HQ2 has up to 6
611. What is the primary mode of operation of TADIL-A?
Roll Call
State the purpose of TADIL-A and TADIL-C?
The exchange of real time tactical data
611. What are messages used to exchange information over TADIL-A known as?
M-series
612. Which module of the AN/GRC-171B(V)4 controls all activities of the tranceiver?
ECCM processor
612. What happens to the guard receiver when the tranceiver is keyed? (AN/GRC-171)
It is disabled
612. What is the RF output when in FM mode? (AN/GRC-171B)
50 Watts
613. Which module determines frequency selection when in the HAVE QUICK mode?
ECCM processor
613. What causes all 6's to be displayed on the FREQ/CHAN display?
If an over temp condition occurs
613. What does it mean if the FAULT lamp comes on?
If out of tolerance condition occurs
614. When is the transmit audio compressor circuit automatically enabled? (URC-119 HF)
When Mic audio source is selected
614. State the purpose of the clipper circuit. (AN/URC-119 HF)
Removes the voice peaks to raise RF output
What is the output of the first converter assembly? (AN/URC-119 HF)
The final TX frequency
614. What is the output of the first converter assembly? (AN/URC-119 HF)
The final TX frequency
614. If your antenna is other than 50 ohms, what do you need to effectively communicat with the RT-1446?
Antenna coupler
615. State the purpose of the series limiter located just before the 0-30 MHz low pass filter? (AN/URC-119 HF RX)
Eliminates excessively strong signals thereby protecting the rx from damage
615. What determines which IF filter, following the second mixer, is selected?(AN/URC-119 HF RX)
Depends on the operating frequency
615. What is the purpose of the squelch circuit? (AN/URC-119 HF RX)
Eliminate background noise
616. What is the purpose of relay A3K1?
(remote control principles)
Routes signal directly from antenna to Transceiver when receiving
616. What accomplishes all the amplification within the AM-7223?
The A1 tube assembly
616. What controls both cathode bias and cathode current in AM-7223?
The A5 power control PWB in response to both keyline and tune control circuits
616. Explain the difference between compressor circuit functions in the remote control compared to compressor circuit functions int the RT-1446
There is no difference
616. Identify the outputs that are muted by the squelch circuit in the C-11329/URC.
Only speaker and headset outputs
617. Define "transmission line" and give an example of one
Conductor or a series of conductors used to carry energy from source to load; stereo cord, Phone cord
617. What are some of the types of transmission line losses?
Resistive (copperloss)
Skin effect
radiation and inductance losses
617. Name two methods of reducing induction loss.
The use of standoff insulators and sheilding
617. What are the major power losses due to in a flexible coaxial cable?
Dielectric and skin effect
617. Why is there very little radiation loss in a rigid coaxial cable?
Because the radiation is confined between two conductors
618. What determines the characteristic impedance (Zo) of a transmission line?
Capacitance and Inductance
618. As signal frequency decreases, what happens to wavelength?
The wavelength increases
618. What does "cutoff frequency" refer to when talking about transmission lines?
If Xl is large and Xc is small then the signal will be developed across the series inductance and shunted across the line by the capacitance therfore would not pass
618. Define "wavelength"
The distance in space occupied by one cycle of a wavelength
618. Identify the primary determinants of a line's capacitance.
size of conductors, space between them, and dielectric material
619. What is the unit of measure for electical length?
Number of wavelength's
619. What happens to electrical length as signal frequency decreases?
Electrical length decreases
619. Describe how a transmission line's characteristic impedance is affected by changing its physical length.
Changing the physical length of a transmission line has no effect on characteristic impedance
620Describe a nonresonant transmission line?
It has no reflected waves
620. What is an incident wave?
Voltage and current waves that move from source to load
620. What is a standing wave?
The vector sum of forward and reflected signals
620. Define "VSWR."
Maximum voltage found at line compared to its minimum voltage
620. If a transmission line has a perfect impedance match what would the VSWR be?
1:1
621. At what level will voltage be at an open termination?
Maximum
621. What is the phase relationship between forward and reflected voltage waves when the line is terminated in a short?
180 degrees
621. What can you use to match a 50-ohm cable to a 600-ohm antenna?
A balun
622. At what frequencies are waveguides used?
For Fx so high that their wavelength is muniscule (tiny)
622. What physical properties determine the characteristics of a rectangular waveguide?
Height and width
622. Aside from lower conductor loss, what is the greatest merit of a waveguide?
Simplicity of construction
622. What factor limits the use of flexible waveguides
Greater power losses because inner surfaces are not smooth
622. What effect does internal moisture have on a waveguide?
Internal arcing
623. Which method of propagation is most dependent on the type of surface between two antenna's?
Surface wave
623. What two components make up the space wave?
Ground reflected wave and the direct wave
623. Define "radiation angle."
The path above the horizon through which the antenna radiates the largest amount of RF energy.
623. What term defines two or more signals arriving at the receiver from different paths and interfering with each other?
Multi path interference
623. Define "skip zone."
Area that exists between the longest ground wave range and the shortest sky wave range where no signal exists
624. Define "reciprocity."
The ability of an antenna to rx and tx equally well
624. If a wave is horizontally polarized, in what direction do the electric lines of force lie?
horizontal
624. What is an isotropic antenna?
Theoretically perfect radiator that radiates equally well in all directions
625. What is a drawback of using an omnidirectional antenna?
Allows interference from any direction to interfere with rx signal
625. How can interference and interaction be reduced when using a bidirectional antenna?
Placing other antennas in the nulls of bidirectional of antenna
625. What is the relationship between "directivity" and "radiation angle."
No relationship
626. Why are vertical antennas practically useless in areas of dense vegetation?
Ground wave is absorbed by surrounding growth
626. With no accessory kit, what is the maximum power that an AN/GRA-4 can handle?
100 watts
626. Which antenna type operates over a wide range of frequencies and exhibits essentially constant characteristics over this entire range?
Log periodic
626. What type of antenna can be used to determine the location of a transmitter?
direction finding antennas.
627. What is the purpose of an antenna coupler?
To match the equipment to the transmission line and antenna
627. How many channels can one CU-547/GR support?
4
627. State the purpose of relays A1A1K1 and A2K2 in the CU-2310 antenna coupler.
Bypass the tuning elements to provide an RF path when the coupler is not tuned to a specific frequency.
What happens in the CU-2310 if the VSWR exceeds 2:1?
The logic circuits react by disabling the keying Circuits