What was found
ON DEPARTURE COM 1 HAD INTERMITTENT CLICKING, UNABLE TO TRANSMIT OR RECEIVE. VHF 1 WAS SHOWING TX ON BOTH ARCDUS & STBY COM. UNPLUGGED CA HAND MICROPHONE & CLICKING STOPPED. TX DISAPPEARED ON BOTH ARCDUS & STBY COM. RETURNED TO FIELD. LANDING UNEVENTFUL. REMOVED FROM SERVICE. COULD NOT DUPLICATE PROBLEM ON GROUND. DUE TO HISTORY R&R BOTH HAND MIC IAW AMM 23-51-21-000-801/400-801. R&R NR 1 VHF TRANSCEIVER IAW AMM 23-11-01-000-801/400-801. ALL TEST GOOD. AIRCRAFT RETURNED TO SERVICE.