AN/ARC-131

RT– 823 / ARC-131 and C-7088 / ARC-131 radio control

Communication

1967

VINTAGE AVIONICS

AN/ARC-131 FM LIAISON SET

Radio Set AN/ARC-131 is a lightweight FM airborne radio set designed for use in aircraft for air to-air and air-to-ground communications, airborne retransmission and CW homing. The set was made by Magnavox, based on their vehicular VRC-12 series of FM transceivers in the same frequency band.

The set is also known as FM-622A

The AN/ARC131 is capable of transmitting and receiving on any one of 920 channels, spaced 50 kHz, within the frequency range of 30.00 to 75.95 MHz. Frequency deviation is 8 kHz. There is a 300Hz-3kHz audio in- and output, and a 40Hz-20 kHz wide band in- and output for coded voice or data transmission.

The power output of the AN/ARC131 is selectable on the RT front as either 10 watts min. (HI) or 1 watt nominal (LO)

Input power requirement is 28 Vdc at 4 amps dung transmit or 1.0 amp when receiving.

Major components of the AN/ARC-131 are as follows:

RT-823/ARC-131 ............. Receive-Transmitter

C-7088/ARC .................... Control

MT-3664/ARC-131 ........... Mount

For communication and ADF antennas see the ARC54 page.

The unit has 3 tubes ( in the receiver front end) and 91 transistors, many germanium pnp.

The ARC-131 frequency synthesis block diagram is here. With the famous Crystal Reference System (CRS). All internal coax connectors are not SMA types but (rare) SMB types.

A picture of the inside is here

A detailed picture of the (transistorised) power amplifier and VHF tuner parts are here.

All circuit diagrams are here

All modules in the RT823 ARC-131 are shown below. The VHF tuner is shown separately because it was acquired later.

Top row, left to right: Crystal Reference System (CRS), IF amplifier, Master oscillator/buffer, RF power amplifier.

Middle row: Power supply, RF control, Mechanical Tuning.

Bottom row: IF attenuator, Homer, reference oscillator, modulator, rcvr audio.

To the right is what remains: the chassis with all wiring, front panel controls, 6 relays, and the main 50-pole plug with filter. Click here to enlarge.