AN/GRA-39Radio Set Control Group Modification. Addition of Two Capacitors and a Choke to Microphone Input Circuits Enables AN/GRA-39to be Used with New MC hf Radio Systems.

摘要

Laboratory tests verify the reported susceptibility of the AN/GRA-39to powerful hf fields. Instability results from detection of the envelope of an AM signal by the remote unit microphone amplifier input circuit. The modification reduces the rf vulnerability of the remote unit by 40-60dB over the 2-30MHz band. The modified AN/GRA-39is shown to be operationally compatible with the TSEC/KY-65narrowband secure voice unit.