RF Input Circuits

TM 11-5820-695-35

selectable by a meter selector switch for monitoring on

amplified and mixed with a local oscillator signal in the

meter panel assembly 2A16A2. The 4.33 to 5.07 GHz

4.33 to 5.07 GHz range to produce a 70 MHz it signal.

output of 2A8 is applied to local oscillator bandpass filter

The if signal is demodulated to recover the composite

2FL6 which is set to pass a specific signal within the

pcm and ow signal. The pem and ow signal is amplified

4.36 to 5.07 GHz range and which is 70 MHz above or

for application to digital data modem 1A12 in

below the 4.4 to 5.0 GHz rf input signal. The 4.65 to

Transmitter, Radio T-1054/GRC-144.

Signal paths

4.85 GHz input to 2A8 is produced by electrical

through

the

R1467/GRC-144,

the

functional

frequency synthesizer 2A14 and amplifier-frequency

relationships between assemblies, and the alarm and

multiplier 2A10. Electrical frequency synthesizer 2A14

metering functions are illustrated-in figure 6-18. The

generates a highly stable frequency in the range of

signal processing circuits in the R-1467/GRC-44 are

284.375 to 303.125 MHz which is adjustable in 6.260

functionally divided into rf input circuits, amplifier-mixer

kHz steps. The output level (synthesizer meter), alarm

circuits, local oscillator circuits, 70 MHz if amplifier

status (synthesizer monitor), and temperature conditions

circuits and demodulator circuits. Receiver, Radio R-

of 2A14 are monitored at the meter panel assembly.

1467/GRC-144 also contains alarm monitoring circuits,

Amplifier-frequency multiplier 2A10 multiplies (times 16)

meter circuits, and power circuits.

the 284.376 to 303.125 MHz output of 2A14 up to the

4.55 to 4.85 GHz signal which is applied through

RF Input Circuits. The rf input circuits

bandpass filter 2FI.1 to receiver frequency mixer stage

consist of preselector bandpass filter 2FL4, tunnel diode

2A8.

amplifier 2A2, and post selector bandpass filter 2FL5.

Preselector bandpass filter 2FIA is set to the specific

70 MHz IF Amplifier Circuits. The 70 MHz

operating frequency in the 4.4 to 5.0 GHz range and

output of amplifier-mixer 2A7 (result of mixing the 4.4 to

passes that frequency. Tunnel diode amplifier 2A2

5.0 GHz rf input signal with the 4.36 to 5.07 GHz local

amplifies the signal, provides isolation, and improves

oscillator signal) is applied to 70 MHz bandpass filter

the receiver's noise figure. Post selector bandpass filter

2A6. Filter 2A6, which has a center frequency of 70

2FL5 is set to the same frequency as 2FL4 and limits

MHz and a 5.0 MHz bandwidth, passes the 70 MHz if

the passage of out-of-band noise generated by tunnel

signal to 70 MHz intermediate frequency amplifier 2A5.

diode amplifier 2A2. The operation of an oven within

The low level 70 MHz if signal is amplified in 2A5 for

tunnel diode amplifier 2A2 is monitored at meter panel

application to demodulator 2A4. The gain of 2A5 is

assembly 2A15A2. The amplified output of 2A2 is

controlled by an age circuit within 2A5. The agc (agc

passed through 2FL5 to amplifier-mixer 2A7.

metering) and 70 MHz if carrier (carrier (if) monitor and

carrier (if) metering) levels are monitored, through alarm

Amplifier-Mixer Circuits. Amplifier-mixer

monitor 2A12 and meter selector switch, respectively, at

2A7 receives the 4.4 to 5.0 GHz rf input signal from

the meter panel assembly. In addition, the agc output,

2FL5 and converts it to a 70 MHz if signal. Conversion

which is proportional to the received rf signal level, is

is made by mixing the 4.4 to 5.0 GHz rf input signal

applied to Indicator, Antenna Alignment ID-1708/GRC.

from 2FL5 with a 4.33 to 5.07 GHz local oscillator signal

from 2A8 applied through 2FL6. The local oscillator

Demodulator Circuits. The amplified 70

signal is 70 MHz above or below the rf input signal.

MHz if signal from 2A5 is applied to demodulator 2A4.

Diode currents generated within 2A7 are selectable by a

A discriminator circuit in 2A4 converts the 70 MHz if

meter selector switch for monitoring on meter panel

signal to a base band signal comprised of pcm and

assembly 2A15A2. The amplified 70 MHz if output of

orderwire signals. The baseband signal is then applied

2A7 is applied through 70 MHz bandpass filter 2A6 to 70

through 1.0 MHz/3.8 MHz lowpass filter 2A3 to af-rf

MHz intermediate frequency amplifier 2A6.

amplifier 2A11.Af-rf amplifier 2A11 amplifies the signal

which is sent to Transmitter ,Radio T1054/GRC144. A

Local Oscillator Circuits. A 4.33 to 5.07

level control is provided in 2A11 to adjust the signal

GHz local oscillator signal is developed within receiver

output level.

The amplified signal output (traffic

frequency mixer stage ZA8 by mixing the 220 MHz

monitor) is monitored at the meter panel assembly.

output from 220 MHz frequency multiplier-osc 2A13 with

the 4.55 to 4.85 GHz output from bandpass filter 2FL21.

Frequency mixer currents generated within 2A8 and the

220 MHz output (multiplier-osc meter) of 2A13 are

Change 1

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