FO RPT ON A-320 EXPERIENCING A RADIO COM DESIGN PROB. WHINE ON FREQ 135.97 IN ZAU AIRSPACE.

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TODAY'S OCCURRENCE SEP/XX/94 IS NOT FIRST TIME PROB WITH LOUD WHINE IN FREQ 135.97 HAS BEEN NOTED WHEN DEPARTING CHICAGO AND BEING HANDLED BY SAME ZAU. THE FREQ WHINE HAS BEEN RECOGNIZED TO BE EXCLUSIVE TO A-320 ACFT; ON FREQ 135.97; WHEN FLC USING #1 RADIO -- (DOES NOT HAPPEN WHILE 1 CREW MONITORS #2 TO CHK) ADVISED BY ATC THAT THIS OCCURS REGULARLY ALWAYS WHEN ON THIS FREQ IN THIS CTRS SPACE; WHILE CREW USING #1 RADIO; IN ONLY AIRBUS A-320 ACFT. THE PROB SEEMS TO BE NO ONE HAS MADE A WRITTEN RPT SINCE 2 YRS AND SHOULD BE SUFFICIENT TIME FOR SOME AGENCY OR MANUFACTURER TO HAVE ADVISED USERS OF A-320 OF A PROB; WHEN IFR IN HVY PERIOD TIMES VERY ANNOYING IN HIGH WORKLOAD AREA. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR WAS CALLED BACK TO CLARIFY HIS STATEMENT REGARDING THE WHINE HEARD ON THE ZAU FREQ OF 135.97. WHEN ASKED TO ELABORATE ABOUT THE DISAPPEARANCE OF THAT WHINE; THE RPTR CLRED UP HIS PREVIOUS STATEMENT AND SAID THAT 'THE WHINE DISAPPEARED WHEN THE FLC MONITORED THE SAME FREQ OF 135.97 AT THE SAME TIME ON THE #2 VHF.' #2 VHF IS USUALLY ON COMPANY FREQ (ARINC) OF EITHER 130.17 OR 131.50. IT ISN'T KNOWN IF THERE IS A HARMONIC SET UP BY THE FREQ SELECTION ON THE #2 VHF. SINCE ATC HAD SAID THAT THEY RECOGNIZED THAT THIS PROB EXISTED ON 'ALL A-320'S;' THEY SHOULD ASK THE FLCS TO SELECT THAT CTR FREQ ON #2 VHF IN CONCERT WITH #1 VHF AND DETERMINE IF THE WHINE THEN DISAPPEARS FROM THE CTLR'S HEADSET AS WELL. THE ACR HAS NOT INDICATED THAT THERE WILL BE ANY COMPANY ACTION ON THIS ITEM.