Compasses and UHF Tranceivers.

EcoTeam · Post by **EcoTeam** » 29 February 04 11:40 pm

Just thought I'd pass this on...
Don't get your UHF Tranceiver too close to your magnetic compass, the magnet in the speaker on the transceiver will upset the compass.

I fell for this one a little while back. I was heading to GZ 100m or so in the scrub and was following the compass bearing from the road. I was heading in a straight line but my GPS told me I was not getting any closer to the cache. I though it was the usual problem of the GPS not updating, so I kept going knowing that I was going in the right direction. When I got to what I thought was close to GZ, the GPS was saying the cache was still 100m away. Then I checked the compass again and it now pointed where the GPS was pointed. A second later it dawned on me... I had the compass around my neck on a cord, and had picked up to check the compass with the same hand I was holding the transceiver with. The magnet in the speaker had upset the compass and I followed the wrong bearing

It turns out that the compass can be effected up to 20cm away from my transceiver, others will vary of course.

Obvious really, but one to watch out for!

EcoDave

GeoQuacks · Post by **GeoQuacks** » 29 February 04 11:46 pm

Our GPS affects our magnetic compass. Not to the degree that EcoTeam got affected, but it causes you to approach a cache on a shallow arc rather than directly if not careful.

Peter

EcoTeam · Post by **EcoTeam** » 01 March 04 12:03 am

GeoQuacks wrote:Our GPS affects our magnetic compass. Not to the degree that EcoTeam got affected, but it causes you to approach a cache on a shallow arc rather than directly if not careful.

Peter

Which GPS?
I've experimented with my eTrex over the years, and it seems ok with every compass I've tried so far.

Definitely possible if your GPS has some magnitised material in it though.

EcoDave

GeoQuacks · Post by **GeoQuacks** » 01 March 04 12:07 am

Garmin GPS 12

swampgecko · Post by **swampgecko** » 01 March 04 6:52 am

GeoQuacks wrote:Garmin GPS 12

I have noted the same with my Garmin 12, and I also carry a handheld radio normally.... that might explain a few things

GeoQuacks · Post by **GeoQuacks** » 01 March 04 7:01 pm

It certainly does put on weight with those four batteries!

EcoTeam · Post by **EcoTeam** » 01 March 04 7:15 pm

Just tried it...
My Jaycar Powertech 2000 NiMh batteries affect the compass in or out of my eTrex, but they have to get very close, right under the compass in fact. They have no affect from the side. My old NiMh rechagables didn't do this. Guess the new ones have either picked up a magnetic charge somewhere, or they are manufactured that way.
I can confirm that my eTrex (without) batteries has absolutely no affect in any position regardless of how close.

In practice this would never be a problem for me, as I would not rest my compass on my upside down eTrex!

I guess you could run your batteries through a demagnitiser if you really wanted too though?

EcoDave