GPS Damage from VHF

[mbrandt]

I posted this on my mailing list and didn't get any response so I thought I would try this here. Conventional wisdom says don't mount your VHF antenna close to your GPS as it will DAMAGE the GPS. I am not talking about interference when you key the mic, but frying the GPS circuitry. After doing extensive search of the archives and other places on the net, all I can find is "I know somebody this happened to", but I have never seen the actual person say it happened to them. The closest I could find were some posts about some magazine guys testing and they fried 4 GPS units. I could not find the actual article, just the relayed report. I also read that ALL the GPS manuals say the same thing. I read thru mine and couldn't find any reference and went to the Garmin site and didn't see anything there. You would think they would warn you if this is true. I mean think about it, boats, vhf, gps. You would think that with all the GPS and all the VHF radios out there, this would be common occurence. We're all not eletronic genuises. So has this happened to YOU!

Thanks!

Mark

[Thom]

Mark,

My last GPS was a Garmin GPSMap-210 and its antenna was mounted 12" away from the VHF antenna (Shakespeare 5399) that was connected to my ICOM M-127 radio. It was mounted like that for three years and I used the radio quite a bit over those years. It had no effect on the GPS, which was working perfectly when I sold it last December. It may be of interest to you to know that the radio's actual output, measured on channel 16 was 29 watts each time I checked it (I do that every couple of months with a SWR/Power meter I have just to make sure I'm not getting into corrosion problems at the connector). At the moment I have different antennas mounted in the same mounting locations. I now have a Garmin 17N antenna, which is actually both the antenna and the GPS receiver, which is the feed unit to my new Garmin 2006 and the VHF antenna that is a foot away is now a Shakespeare 5225XT that is connected to my backup radio, which is an ICOM M-59 (24 watts comming out of this one). Based on my experience with the past close mounting I don't expect any problmes with this proximity either. Oh, it may be of some interest to you that my radar is mounted 3 feet away from both of them. This is a small 2kW radar (Raytheon SL-72) and I checked with Garmin before the mounting. They told me to make sure that the Radar did not shoot straight into the GPS antenna. The reason they gave was not that it would hurt the GPS receiver but that they expected it would cause preamature aging of the plastic the antenna was made of. Consequently I mounted the GPS below the centerline of the radardome so the outgoing signal (microwaves actually) would not cook the plastic.

Thom

[mbrandt]

Thanks for the input Thom. I thought most of it was needless worry. Was getting ready to mount a VHF, first one for me, and was a little concerned with some of the past postings. I now feel safe in putting the antenna in any location that I want, rather than worry about wrecking something else. Can't move the GPS antenna as it is internal. It's amazing how some of this stuff gets started. I'll wait a while and see if anyone else responds.

Thanks again!

Mark