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3D156 - Volume 1 > Unit 5. Transceivers > Flashcards

Unit 5. Transceivers Flashcards

1
Q
  1. Capabilities and limitations

1. AN/GRC–171 and AN/GRC–211 radio sets are designed for what purpose?

A

Air traffic control communications sites for fixed and portable, point-to-point and ground-to-air communications.

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2
Q
  1. How many channels are available when using the AN/GRC–171 or AN/GRC–211 radio?
A

The UHF version of the transceiver can communicate on any one of 7,000 available channels. The VHF version of the transceiver can communicate on any one of 1,440 available channels.

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3
Q
  1. What is the transmit duty cycle for the AN/GRC–211 radio?
A

Continuous unattended.

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4
Q
  1. Which version is more sensitive, UHF or VHF, and why?
A

VHF, because of the RF preamplifier.

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5
Q
  1. Match the characteristic in column A with the appropriate transceiver in column B.
A

Column A
____ (1) Continuous receive duty cycle, 90 percent duty cycle transmit.
____ (2) 25 W output power.
____ (3) 85-95 percent modulation.
____ (4) Continuous duty cycle, transmit and receive.
____ (5) Wideband audio output of at least 0.5 V across a 10
kilohmns (k

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6
Q
  1. Theory of operations

1. Where does the transmit RF originate?

A

Frequency synthesizer A2.

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7
Q
  1. What is the purpose of the RF filter during transmit?
A

To eliminate harmonics.

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8
Q
  1. What are the characteristics of key 1 and key 2?
    Column B
    a. AN/GRC–171 (UHF). b. AN/GRC–211 (VHF).
A

Key1–FASR;key2–SAFR.

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9
Q
  1. What change does key 1 cause in the frequency synthesizer in the transition from transmit to receive?
A

It causes the frequency of the frequency synthesizer to shift its frequency up 30 MHz from the operating frequency in the AN/GRC–211 and down 30 MHz from the operating frequency in the AN/GRC–171.

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10
Q
  1. Describe the RF paths in the receive signal flow for UHF and VHF versions.
A

From the antenna through the RF filter module A7 to the RF receiver module A3. The VHF version inserts a preamplifier between the A7 and the A3.

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11
Q
  1. What is the purpose of the RF filter during receive?
A

To eliminate image frequencies and provides preselection.

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12
Q
  1. What makes these radios dual conversion receivers?
A

The second mixing of the signal.

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13
Q
  1. In the AN/GRC–211, where are the first and second IF produced?
A

The first is produced in the UHF mixer, and the second is produced in the second mixer.

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14
Q
  1. What is the frequency response of the HP and LP filters in the receive A4?
A

300 to 3,000 Hz.

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15
Q
  1. Which part of the radio converts the AC into an unregulated DC voltage?
A

Transformer/rectifier on the chassis A10.

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16
Q
  1. Which part of the radio contains a switching-type voltage regulator?
A

A5 module.

17
Q
  1. Which input to the D/A servoamplifier module A1 tells the servo where the filter is tuned?
A

Position feedback (POSN FB) input.

18
Q
  1. What would be the condition of the filter given the following conditions? a. POSN FB =
A

a. Tuning up.
b. Tuning down. c. Tuning up.
d. Tuned.
e. Tuning up.

19
Q
  1. Capabilities and limitations

1. What components make-up the AN/TRC

A

RT

20
Q
  1. What components make-up the AN/PRC–113 radio set?
A

RT

21
Q
  1. List the operating frequency range of the RT.
A

VHF (116.000 – 149.975 MHz) and UHF (225.000 – 399.975 MHz).

22
Q
  1. What is an acceptable percent of modulation for the RT?
A

87% ±7.5%.

23
Q
  1. What is the output power of the RT?
A

2 or 10 W (operator selectable).

24
Q
  1. Why is it essential to properly identify your transceiver set’s version?
A

The different versions require different part numbered assemblies in-order to function properly.

25
Q
  1. Basic theory of operations

1. How is the main receiver tuned?

A

By the data converter (A1) which accepts information from the front panel keyboard.

26
Q
  1. To what frequency is the guard receiver tuned?
A

243.000 MHz.

27
Q
  1. Which assemblies contain the transmit circuits?
A

The modulator (A3) and transmitter (A2) assemblies.

28
Q
  1. Where does the modulator get the carrier frequency?
A

The synthesizer.

29
Q
  1. What circuits are contained in the transmitter assembly?
A

2 and 4 watt broadband RF power amplifiers, RF switching networks, output low pass filters, a thermal sensor to detect possible overheating, and a reflected power sensor.

30
Q
  1. How is overheating controlled in the RT?
A

The thermal sensor circuit switches the transmitter to low power operation.

31
Q
  1. What functions does the microprocessor controlled data converter perform in the RT?
A

Keyboard decoding, LCD display control, mode control for all functions of the RT, and synthesizer frequency control.

32
Q
  1. What regulated voltages does the power regulator supply?
A

+6.3 VDC, -29 VDC, -13.5 VDC and +12 VDC.

3D156 - Volume 1 (8 decks)

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