ARM-47 UHF comm test set

The  ARM47 testset can test both the receiver and transmitter part of most UHF airborne radios.


Receiver test:  A signal is generated at harmonics of  a  8.850 MHz or 9.000 MHz  Xtal oscillator. 20 harmonics can be selected  between 225-400MHz, amplitude modulated with 1kHz, and with adjustable, stabilized level. With the meter at the red mark, the RF level is -90 dBm ( 7uV).   The 8.85MHz crystal is operated at 80 deg C  in an oven.


Transmitter test:  A standing wave meter measures forward power on a 0-20W scale, and reflected power in a 20W or  4W scale.  Modulation depth can be measured. The testset is inserted in the antenna cable between transceiver under test and antenna. The testset has no dummy load.   If required, an external dummy load should replace the antenna.


Circuit diagram is here


The ARM-47 Radio Test Set is manufactured by Systems Development for ground or in-aircraft test of the UHF transceivers AN/ARC-27, AN/ARC-34 and with small modification also the ARC-52 and ARC-51 and their antennas.


Short specification

Supply voltage:

                115Vac, 50-400Hz ( 30 VA)

RF Interface: The testset is inserted between transceiver and antenna with male and female N-connector

Audio and control interface:  two jackplugs for  Phone and Mike +PTT .



The small meter shows the generated level during the receiver test. The larger meter shows the forward and reflected power, modulation depth, and audio levels.

UHF Communication





  UHF Comm panels

 ARM47 UHF testset