antenna voltage/problems

[neilsam]

Hey guys, can someone help me out.

I have a gilsson antenna that keeps on losing satelite reception.

I called Gilsson and they said my voltage on my M5 antenna connector is too low- (although its within range of 2.5-5v).

My voltage is reading 3.02 Volts.

Can you let me know what yours reads. I'd really appreciate any replies.

Thanks,

[neilsam]

Just wanted to clarify: All i need is someone to get a voltage meter, and touch the contacts of the antenna on the Ique M5 and let me know what the reading says.

I'd really appreciate it.

ps: please make sure the GPS is on

[jonasolof]

It can't be done like that, because the voltage drops under load. The iQue 3600 gives 2.66 volts with no load, with a Gilsson voltage drops to 2.0 volts, with a Wi-Sys 3910 slightly less.

To measure, I took a short cable with a mcx female at one end and a male mcx at the other end and opened it up in the middle so that current draw and voltage can be measured at the same time (with two instruments). With this cable between the antenna and the PDA, I can measure any antenna without messing around with its connector. GPS reception will be impaired of course, but that doesn't matter. I have never seen a M5 outside of fairs so I can't help you.

I think they only guessed at Gilsson. They know, though, that Garmin has played some tricks. The Garmin 27C antenna consumes little power and works down to 1.5 volts, albeit with lower amplification than the others, since it has only a one stage amplifier, whereas all other have two. One can see this as a way for Garmin to ensure less competition for external antennas, or that they found it difficult to design circuits that would give let's say 10 mA at 2.5 volts at the antenna connector which would be optimal.

Since others haven't reported any problems, and I guess some use external antennas, my preliminary guess is that there could be something wrong with the antenna, although this is also very rare. There could also be something wrong with the circuitry in the M5 that handles the signal from the external antenna.

The cheapest solution, but maybe not so attractive, is simply to get another Gilsson or possibly Wi-Sys 3910 and try it. I would start by measuring voltage under load though. The Gilsson is dorn 5 dB at 2.0 volts compared to 5 volts (if I remember right), and at 1.8 volts amplification has dropped a lot.

So if you have 2.0 volts or more at 5-7 mA draw, that's enough.

If one Gilsson/Wisys works better than another, it's clear.

If you don't get 5-6 sats over the fifth line under an open sky with two good antennas, the M5 is the culprit.

Don't try other brand antennas, because they draw more current and you need to have the characteristics of each.

[neilsam]

Thanks for the reply.

I have a problem with 2 antenna's that were never there before. 1 antenna still works ( I have a total of 3 Glissons).

I am returning two of them to Glisson to let them figure it out.
I have also ordered a Garmin one just in case.

Hope i dont have to buy 3 Garmin antennas at $70 each:mad:

[jonasolof]

Having two antennas out of three that don't work seems to be extremely bad luck. PLease tell us of the results. I have eight Gilssons, they all work.