AN/ARC-44

VINTAGE AVIONICS

AN/ARC-44 FM LiaISon set

The Radio Set AN/ARC-44 is a lightweight FM airborne radio set designed for use in aircraft (mainly helicopters) for air to-air and air-to-ground communications, airborne retransmission and CW homing. The unit shown was built in 1958 by Telefunken, and is compatible with the SEM-25.

The AN/ARC44 is capable of transmitting and receiving on any one of 280 channels, spaced 100 kHz, within the frequency range of 24.0 to 51.9 MHz. Frequency deviation is 20 kHz.

The RF power output of the AN/ARC44 is 8 watts minimum

Input power requirement is 28 Vdc at 5 amps in both transmit and receive. Heaters take 1.7A, tuning motor or T/R relay do 0.7A, and the external dynamotor requires up to 3A to produce +150V/100mA for all tubes except the RF power stage which runs from 300V at 80mA when transmitting. The fan inside the ARC-44 is a 27Vac, 3-phase 400Hz type, also supplied from the dynamotor.

The unit has 29 tubes, no transistors nor diodes.

Major components of the AN/ARC-44 are :

RT-294A/ARC-44 .......... Receive-Transmitter

SB- 327/AR .................... Frequency Control Panel

SB-329/AR …………. Audio Distribution Panel (INT)

DY-107 ………….... External Dynamotor

AT 454 …………… Communication antenna

AN/ARA -31 ……….... Homing antenna system (optional) with :

SA-474 switch panel

Keyer KY 149

and 2 vertical dipole antenna’s with balun

Diagrams: External wiring

RF part ( and first IF)

IF and audio circuits

Shown below is the ARC-44 with front , top and rear cover removed, and both side covers down.

The large module on the front is the RF module built around a seven-section variable capacitor. The smaller block in the middle is the first (tuned) IF amplifier around 7 MHz. The second IF and audio modules are mounted on the left and right covers.

RT-294A / ARC-44 with SB-327/AR control panel