Narrative:

Tower cleared us for takeoff. Then, after takeoff from oak runway 15, departed on 045 degree right. At handoff time from tower to departure control, no audio, so missed handoff. Abeam the oak hills, still no contact. Suspect #2 transmitter intermittent on modulation. I immediately descended beyond the hills so as to stay out of the arsa. (#1 transmitter reset to departure control, but call not answered). Changed to napa tower, no response, changed headsets, problem solved for #1 communication only. #2 still no transmit modulation. Now awaiting avionics repair technician's report. History: recent problem of no transmit modulation, transmit '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 problem solved when discovered. Equipment comment: communication unit has no squelch adjustment for pilot. Some frequencys are very noisy, so tendency is to use navigation communication only. Radio technician found squelch way off and faulty output on. Repaired and now operating properly. Headset replaced. Callback conversation with reporter revealed the following: reporter called oak tower and was advised they had no information on the incident. Analyst advised in the future if he has communication problems to use 7600 versus 7700 on his transponder. Is concerned of the noise abatement procedure at oak reference to vectors over the masonic temple and is sure there will be complaints.

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Original NASA ASRS Text

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

Narrative: 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.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.