AN ATX PLT (PA31 PIPER NAVAJO) RPTS THAT THE USE OF ILS FREQ 108 PT 9 CREATED A LOSS OF HIS GARMIN 195 GPS SIGNAL. THIS WAS CHKED SEVERAL TIMES FOR REPEATS OF THE INITIAL EVENT.

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I HAVE NOTICED THAT ON ABOUT 50% OF MY ARRS INTO THE SANFORD ARPT (SFB); MY GPS LOSES ITS SATELLITES AND CEASES TO PROVIDE INFO. ON THIS PARTICULAR DAY; WX AT SFB LOOKED ROUGH; SO I TUNED IN THE ILS 9 LOC FREQ 108.9 DURING CRUISE ABOUT 80 MI OUT TO PLAN THE APCH. WITHIN 2 MINS; I NOTICED THAT MY GARMIN 195 MAP HAD LOST ITS SATELLITES AND FAILED TO PROVIDE STEERING DATA. I CHANGED THE FREQ IN THE NAVAID WINDOW TO A DIFFERENT FREQ AND WITHIN 2 MINS THE GPS RETURNED TO NORMAL. I REPEATED THE TEST SEVERAL TIMES WITH THE SAME RESULT -- THE ILS FREQ OF 108.9 SOMEHOW INTERFERES WITH THE GPS. IN FLT TODAY; I ASKED A COMPANY FLT IF HE HAD EVER HAD ANY GPS PROBS IN THE SFB AREA. HE HAD ON NUMEROUS OCCASIONS. I TOLD HIM OF MY DISCOVERY AND HE TRIED IT INBOUND TO SFB. HIS GPS WAS A TRIMBLE BUT THE RESULT WAS THE SAME: TUNING 108.9 SHUT DOWN THE GPS DATA. I NOW KNOW THAT THE PROB HAS NOTHING TO DO WITH LOCATION; BUT ONLY OCCURS WHEN 108.9 IS TUNED. THOUGHT YOU'D BE INTERESTED. THE TIMES I HAD LOST DATA APCHING THE SFB ARPT WERE NOT RANDOM BUT HAPPENED ONLY WHEN WIND/WX CAUSED ME TO TUNE 108.9. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT HIS ACFT WAS A PA-31 PIPER NAVAJO. HE WAS SUPPLEMENTING HIS NAV CAPABILITY WITH THE GPS WHICH WAS HIS OWN AND WAS MOUNTED ON THE YOKE WITH THE ANTENNA LAYING ON THE GLARE SHIELD. THE UNIT WAS NOT CERTIFIED FOR IFR; FOR VFR ONLY. HE NOW FEELS THAT HAD HE PLACED THE ANTENNA BEHIND HIM; AWAY FROM THE RADIO CONSOLES; THAT THE USE OF 108.9 ILS FREQ WOULD NOT HAVE INTERFERED WITH THE GPS SIGNAL. A FRIEND OF HIS USED A TRIMBLE GPS; TYPE NUMBER UNKNOWN; AND EXPERIENCED THE SAME ANOMALY AS HE HAD WITH THE USE OF 108.9 ILS FREQ. THE RPTR ALSO SPECULATED THAT IT MIGHT NOT HAPPEN WITH EVERY ACFT BUT WOULD DEPEND UPON THE TYPE AND THE WIRING OF THE ACFT. HE THOUGHT THAT THIS EVENT WAS SO UNIQUE THAT THE GPS MANUFACTURERS SHOULD KNOW ABOUT IT FOR ISSUANCE IN THEIR INFO BULLETINS.