ACR RPTS PROBS WITH 1 OF 2 VOR RECEIVERS ONLY ON 1 FREQ WHILE PAX ARE USING ELECTRONIC DEVICES IN CRUISE.

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WE ENCOUNTERED SOMETHING STRANGE WITH THE MCI VOR. BOTH THE CAPT AND I WERE TUNED TO IT; BUT ONLY THE CAPT WAS RECEIVING A SIGNAL AND GOOD IDENT FROM IT. THIS HAPPENED ON J25; WELL WITHIN THE VOR SVC VOLUME. EVEN AT 60 NM TO AND FROM THE MCI VOR; NO SIGNAL AND/OR IDENT ON MY RECEIVER. MCI JUST CHANGED OVER TO NEW FREQ 113.25 THIS PAST MONTH; BUT I DOUBT THAT HAS ANYTHING TO DO WITH THIS. I FLY 'JURASSIC JET' A DC9-50. OUR MAINT PEOPLE CHANGED OUT THE RECEIVER. SO; HERE'S SOME OF THE FACTORS: 1) BOTH VOR ANTENNAS ARE LOCATED IN SAME PLACE -- THE TAIL; SO BOTH SHOULD HAVE GOTTEN THE SAME SIGNAL. 2) MY RECEIVER THAT WOULD NOT GET ANY SIGNAL IDENT FROM MCI; WORKED FINE ON ALL OTHER FREQS USED FOR THE REST OF THE FLT. I CHKED OUT ON THE GND WITH VOT TEST FREQ. 3) THE FLT ATTENDANTS DID MENTION THAT 4 PAX WERE USING LAPTOP COMPUTERS AND 2 PALM PILOTS. (IF THESE WERE THE CAUSE; WHY DID IT ONLY AFFECT 1 SIDE?) WE NEVER DID TRY HAVING PAX TURN OFF ANYTHING TO SEE IF IT SOLVED OUR PROB AS WE WERE VFR IN CRUISE. HOWEVER; THINGS COULD HAVE BEEN VERY DIFFERENT HAD WE BEEN IN AN 'ELECTRIC AIRPLANE' (IE; A320 OR B757) AND ON APCH. THIS WAS ONE TIME I WAS GLAD WE WERE FLYING 'JURASSIC JET;' OUR ONLY COMPUTER IN THE ACARS BOX; SO WE SHOULD BE UNAFFECTED BY Y2K; BUT THIS PARTICULAR INSTANCE WAS A STRANGE ONE.