ACR MLG HAD RADIO COM PROBLEMS AGGRAVATED BY ALTDEV AND USING AERIAL PIRACY CODE INSTEAD OF LOST COM CODE.

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AFTER TKOF AT CHS AND SWITCHING TO DEP WE LOST COM. WENT BACK TO TWR AND AFTER ABOUT 2 MINS WE REESTABLISHED COM WITH TWR. TWR GAVE US A VECTOR TO INTERCEPT OUTBOUND COURSE AND CLB TO 10000 FT MSL. AUTOPLT WAS ON AT 2000 FT MSL (BECAUSE OF COM PROBLEMS). THE FLT ANNUNCIATOR PANEL (FMA) HAS VNAV CLB AND ALT ARM ANNUNCIATED. 10000 FT WAS IN THE ALT WINDOW OF THE DFGC. TWR SWITCHED US TO JAX CENTER BUT NO COM WITH JAX. WE THEN TRIED TWR BUT NO COM. THEN WENT BACK TO JAX CENTER. WE TRIED CAPT ON #1 RADIO; FO ON #1 RADIO; CAPT ON #2 RADIO; FO ON #2 RADIO. I DECIDED TO SQUAWK 7600. AS I WAS CHANGING THE SQUAWK TO 7600 I NOTICED THE ACFT CLBING THROUGH 10000 FT WITH VNAV LEVEL ON THE FMA. IT WAS FO'S LEG SO I TOLD HIM TO LEVEL OFF WHICH HE DID. HOWEVER; WE DID GO TO 10500 FT. AT THAT TIME JAX CENTER REACHED US AND CLRED US TO 14000 FT. JAX CENTER ALSO WONDERED IF WE HAD ANOTHER PROBLEM AND I NOTICED 7500 IN THE TRANSPONDER. I TOLD THEM NO WE DID NOT HAVE A PROBLEM. I HAD INADVERTENTLY PUT 7500 INSTEAD OF 7600 IN THE TRANSPONDER OR IT HAD NOT BEEN SET IN THE NOTCH (THE TCASII TRANSPONDERS WILL CHANGE CODES IF NOT SET EXACTLY RIGHT -- ANOTHER LED WONDER). AFTER LNDG IN ATLANTA; MAINT TOLD US THAT A RELAY WAS STICKING IN COM 1 THAT WOULD BLANK OUT RECEPTION IN ALL THE RADIOS. AFTER NOT USING COM 1 FOR AN UNDETERMINED PERIOD OF TIME IT WOULD UNSTICK AND COM COULD BE RESTORED.