Darian replied:

Rob ....had a quick look on the Magellan site....the re-rad looks like a transceiver to me - runs on 12 volts - can't see you doing that with a few bits of wire. I'm lucky with my Lowrance unit - runs very well on the dash (hard on the A pillar) with inbuilt antenna (except for deep/high country). If the re-rad works well, the $150 has to be worth it for mine.
How about you ask Magellan for personal contact with a user ?
.....dp

Bill replied:

Rob, I have a Garmin which has the facility to use an external antenna. I mount mine on the top of the dash and never have any problems - position is all important so before you try making an antenna or spend all that money ... try to get it mounted where it has a good look at the sky!!

Peter replied:

Rob I too have a Garmin, well two actually an old GPS75 single channel/multiplexed unit and a GPS12XL.
The 75 will work ok outside but in the car definitely needs the external antenna while the 12XL works ok but for steep heavily treed country an external antenna is better.
You may find that your gps will work ok up on top of the dash but loses signal when heading south (as the satellites are in an equatorial orbit) and an external antenna is required to overcome it.
If your gps cannot accept an external antenna then as you say a re-radiating antenna/trannsmitter is the only solution apart from upgrading your gps to a different model.
The best place to ask the question would be at www.gpsoz.com.au as Brian is very familiar with what is available.

Peter

Rob replied:

Thanks for the feedback guys. I have just returned from a trip North of Perth with my GPS sitting on the dash and I couldn't believe the number of satellites that I was receiving. Obviously a lot of my problems are coming from trips through the southern forests where I am encountering too many trees.
I will be checking out www.gpsoz.com.au and then working out a way to
either make one or just bite the bullet and buy one.
Cheers