ON ACCOUNT OF COM PROBLEMS DID NOT COPY REQUEST FROM TWR TO CHANGE TO DEP FREQ. NO CONFLICT.

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TWR CLRED US FOR TKOF. THEN; AFTER TKOF FROM OAK RWY 15; DEPARTED ON 045 DEG R. AT HDOF TIME FROM TWR TO DEP CTL; NO AUDIO; SO MISSED HDOF. ABEAM THE OAK HILLS; STILL NO CONTACT. SUSPECT #2 XMITTER INTERMITTENT ON MODULATION. I IMMEDIATELY DSNDED BEYOND THE HILLS SO AS TO STAY OUT OF THE ARSA. (#1 XMITTER RESET TO DEP CTL; BUT CALL NOT ANSWERED). CHANGED TO NAPA TWR; NO RESPONSE; CHANGED HEADSETS; PROB SOLVED FOR #1 COM ONLY. #2 STILL NO XMIT MODULATION. NOW AWAITING AVIONICS REPAIR TECHNICIAN'S RPT. HISTORY: RECENT PROB OF NO XMIT MODULATION; XMIT 'T' DOES ILLUMINATE WHEN CARRIER IS ON; WAS REPAIRED AT COLORADO SPRINGS IN MAY. SET OPERATED NORMALLY UNTIL JUNE MALFUNCTION. EVENT COMMENT: 7700 SQUAWK DID NOT SEEM APPROPRIATE AS PROB SOLVED WHEN DISCOVERED. EQUIP COMMENT: COM UNIT HAS NO SQUELCH ADJUSTMENT FOR PLT. SOME FREQS ARE VERY NOISY; SO TENDENCY IS TO USE NAV COM ONLY. RADIO TECHNICIAN FOUND SQUELCH WAY OFF AND FAULTY OUTPUT ON. REPAIRED AND NOW OPERATING PROPERLY. HEADSET REPLACED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: RPTR CALLED OAK TWR AND WAS ADVISED THEY HAD NO INFORMATION ON THE INCIDENT. ANALYST ADVISED IN THE FUTURE IF HE HAS COM PROBS TO USE 7600 VERSUS 7700 ON HIS TRANSPONDER. IS CONCERNED OF THE NOISE ABATEMENT PROC AT OAK REF TO VECTORS OVER THE MASONIC TEMPLE AND IS SURE THERE WILL BE COMPLAINTS.