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108 Cards in this Set
- Front
- Back
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601. What does "frequency accuracy" refer to when discussing transmitters?
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Ability to maintain a constant output carrier
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601. Name the four basic requirements needed to accomplish any type of modulation.
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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 |
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601. What does the modulation envelope represent?
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Represents algebraic sum of the carrier and sidebands as it would appear
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601. What three frequencies are contained in the modulated carrier wave?
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Carrier, Upper, and Lower
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Define "percent of modulation."
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The amount of effect or change that the intellegence has on the carrier
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What is the formula for Percent of Modulation?
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emax - emin/emax + emin times 100
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602. What is the formula for Percent of Modulation?
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emax - emin/emax + emin times 100
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emax of 50vrms emin of 5 Vrms what is the percent of mod?
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81.8
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602. What are the two results of overmodulation?
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Causes distortion and Am bandwidth increases
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Name the modules that make up the APC circuit
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DC1, A10, A6
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603. Name the modules that make up the APC circuit
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DC1, A10, A6
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603. What does the APC voltage do if the forward power gets too high?
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Varies the gain to make it normal
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603. State the purpose of the e/l relay when operating the transmitter in 10 watt mode?
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Has no Purpose
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604. Why does the UHF multiplier contain one more stage of amplification than that of the VHF version?
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Because the fourth harmonic is weaker than the second
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604. State the purpose of the transmitter's tune/operate switch
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Protect the tunable filter during tuning operation
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604. What happens if the VSWR exceeds 3:1?
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The e/l relay is energized and we bypass the LPA to prevent damage
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604. Why are we concerned with removing the RF from the E/L relay when it is energized?
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To prevent the contacts from arcing
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605. What is the pupose of the linear power amplifier?
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To amplify from 10w to 50w
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605. State the purpose of C1 and L1 in the A4 module (pwr amp)
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Filter ripple out of 2000vdc
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605. In the A5 module, what are the LPA FWD and RVS power sensor voltages used for? (pwr amp)
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Develope APC voltage and detect vswr
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605. State the purpose of the tune operate switch in the pwr amp
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It decreases the exciter RF output to less than 10 watts out, and it prevents the E/L relay from energizing
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606. What is a superheterodyne receiver
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Uses the mixer to make intermediate fx
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606. Why is it necessary for the RF amplifier section to isolate the local oscillator from the antenna?
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If Antenna was connected directly to mixer part of oscillator, the signal could be radiated into space causing interference with other receivers
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606. Define "image frequency."
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Undesired signal that when mixed in the mixer produces the correct IF
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606. What is the difference between a mixer circuit and a converter circuit?
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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
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607. Define "demodulation"
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Recovering intellegence from the modulated wave
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607. Briefly state the requirements for any type of demodulation?
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sensitivity
Nonlinearity RF carrier signal Filtering |
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607. What are the main drawbacks of using diode detectors?
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No pwr gain, Selectivity is affected by loading of the tank
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607. What factor determines the amount of amplification needed in the audio amplifier circuit?
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The type of output device (headphones)
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608. Which module in the AN/GRR-23 and the AN/GRR-24 performs the function of preselection?
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Tunable filter (fl2)
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608. Which module determines overall selectivity? (AN/GRR-23 AND 24)
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Crystal filter (FL1)
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608. What happens to the DC portion of the detector output? (AN/GRR-23 AND 24)
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Applied to AGC section of the A3
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609. In the UHF mixer/multiplier A2, to what frequency would Q1 be tuned if the oscillator synthesizer's output were 67.0 MHz
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268 Multiply by 4
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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)
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20.6 Always
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In what section does most of the rx's amplification take place?
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IF Amplifier
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609. What is the purpose of the receiver's AGC circuit?
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Provide constant audio output with varying RF input
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609. What is the purpose of the receiver's squelch circuit?
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To pass audio at the antenna or to block it
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610. State the purpose of HAVE QUICK radio's
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To prevent hostiles from Jamming the radio's
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610. What is the purpose of WOD and TOD?
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To get the same frequencies at the same time
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610. Why isn't HAVE QUICK considered a means of secure communications?
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It doesn't use encryption and enemy could tune 7000 receiver's
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610. List two differences between HQ1 and HQ2
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Have quick one allows one word to be loaded at a time
HQ2 has up to 6 |
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611. What is the primary mode of operation of TADIL-A?
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Roll Call
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State the purpose of TADIL-A and TADIL-C?
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The exchange of real time tactical data
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611. What are messages used to exchange information over TADIL-A known as?
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M-series
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612. Which module of the AN/GRC-171B(V)4 controls all activities of the tranceiver?
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ECCM processor
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612. What happens to the guard receiver when the tranceiver is keyed? (AN/GRC-171)
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It is disabled
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612. What is the RF output when in FM mode? (AN/GRC-171B)
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50 Watts
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613. Which module determines frequency selection when in the HAVE QUICK mode?
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ECCM processor
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613. What causes all 6's to be displayed on the FREQ/CHAN display?
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If an over temp condition occurs
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613. What does it mean if the FAULT lamp comes on?
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If out of tolerance condition occurs
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614. When is the transmit audio compressor circuit automatically enabled? (URC-119 HF)
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When Mic audio source is selected
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614. State the purpose of the clipper circuit. (AN/URC-119 HF)
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Removes the voice peaks to raise RF output
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What is the output of the first converter assembly? (AN/URC-119 HF)
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The final TX frequency
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614. What is the output of the first converter assembly? (AN/URC-119 HF)
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The final TX frequency
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614. If your antenna is other than 50 ohms, what do you need to effectively communicat with the RT-1446?
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Antenna coupler
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615. State the purpose of the series limiter located just before the 0-30 MHz low pass filter? (AN/URC-119 HF RX)
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Eliminates excessively strong signals thereby protecting the rx from damage
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615. What determines which IF filter, following the second mixer, is selected?(AN/URC-119 HF RX)
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Depends on the operating frequency
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615. What is the purpose of the squelch circuit? (AN/URC-119 HF RX)
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Eliminate background noise
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616. What is the purpose of relay A3K1?
(remote control principles) |
Routes signal directly from antenna to Transceiver when receiving
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616. What accomplishes all the amplification within the AM-7223?
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The A1 tube assembly
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616. What controls both cathode bias and cathode current in AM-7223?
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The A5 power control PWB in response to both keyline and tune control circuits
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616. Explain the difference between compressor circuit functions in the remote control compared to compressor circuit functions int the RT-1446
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There is no difference
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616. Identify the outputs that are muted by the squelch circuit in the C-11329/URC.
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Only speaker and headset outputs
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617. Define "transmission line" and give an example of one
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Conductor or a series of conductors used to carry energy from source to load; stereo cord, Phone cord
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617. What are some of the types of transmission line losses?
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Resistive (copperloss)
Skin effect radiation and inductance losses |
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617. Name two methods of reducing induction loss.
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The use of standoff insulators and sheilding
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617. What are the major power losses due to in a flexible coaxial cable?
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Dielectric and skin effect
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617. Why is there very little radiation loss in a rigid coaxial cable?
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Because the radiation is confined between two conductors
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618. What determines the characteristic impedance (Zo) of a transmission line?
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Capacitance and Inductance
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618. As signal frequency decreases, what happens to wavelength?
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The wavelength increases
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618. What does "cutoff frequency" refer to when talking about transmission lines?
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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
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618. Define "wavelength"
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The distance in space occupied by one cycle of a wavelength
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618. Identify the primary determinants of a line's capacitance.
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size of conductors, space between them, and dielectric material
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619. What is the unit of measure for electical length?
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Number of wavelength's
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619. What happens to electrical length as signal frequency decreases?
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Electrical length decreases
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619. Describe how a transmission line's characteristic impedance is affected by changing its physical length.
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Changing the physical length of a transmission line has no effect on characteristic impedance
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620Describe a nonresonant transmission line?
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It has no reflected waves
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620. What is an incident wave?
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Voltage and current waves that move from source to load
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620. What is a standing wave?
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The vector sum of forward and reflected signals
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620. Define "VSWR."
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Maximum voltage found at line compared to its minimum voltage
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620. If a transmission line has a perfect impedance match what would the VSWR be?
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1:1
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621. At what level will voltage be at an open termination?
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Maximum
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621. What is the phase relationship between forward and reflected voltage waves when the line is terminated in a short?
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180 degrees
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621. What can you use to match a 50-ohm cable to a 600-ohm antenna?
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A balun
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622. At what frequencies are waveguides used?
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For Fx so high that their wavelength is muniscule (tiny)
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622. What physical properties determine the characteristics of a rectangular waveguide?
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Height and width
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622. Aside from lower conductor loss, what is the greatest merit of a waveguide?
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Simplicity of construction
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622. What factor limits the use of flexible waveguides
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Greater power losses because inner surfaces are not smooth
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622. What effect does internal moisture have on a waveguide?
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Internal arcing
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623. Which method of propagation is most dependent on the type of surface between two antenna's?
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Surface wave
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623. What two components make up the space wave?
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Ground reflected wave and the direct wave
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623. Define "radiation angle."
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The path above the horizon through which the antenna radiates the largest amount of RF energy.
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623. What term defines two or more signals arriving at the receiver from different paths and interfering with each other?
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Multi path interference
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623. Define "skip zone."
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Area that exists between the longest ground wave range and the shortest sky wave range where no signal exists
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624. Define "reciprocity."
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The ability of an antenna to rx and tx equally well
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624. If a wave is horizontally polarized, in what direction do the electric lines of force lie?
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horizontal
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624. What is an isotropic antenna?
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Theoretically perfect radiator that radiates equally well in all directions
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625. What is a drawback of using an omnidirectional antenna?
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Allows interference from any direction to interfere with rx signal
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625. How can interference and interaction be reduced when using a bidirectional antenna?
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Placing other antennas in the nulls of bidirectional of antenna
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625. What is the relationship between "directivity" and "radiation angle."
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No relationship
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626. Why are vertical antennas practically useless in areas of dense vegetation?
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Ground wave is absorbed by surrounding growth
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626. With no accessory kit, what is the maximum power that an AN/GRA-4 can handle?
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100 watts
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626. Which antenna type operates over a wide range of frequencies and exhibits essentially constant characteristics over this entire range?
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Log periodic
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626. What type of antenna can be used to determine the location of a transmitter?
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direction finding antennas.
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627. What is the purpose of an antenna coupler?
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To match the equipment to the transmission line and antenna
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627. How many channels can one CU-547/GR support?
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4
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627. State the purpose of relays A1A1K1 and A2K2 in the CU-2310 antenna coupler.
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Bypass the tuning elements to provide an RF path when the coupler is not tuned to a specific frequency.
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What happens in the CU-2310 if the VSWR exceeds 2:1?
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The logic circuits react by disabling the keying Circuits
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