Garmin Antennas

[rviglierchio]

Am using a Garmin 396 and seem to have antenna problems. Is anyone using these finding it difficult to locate the GPS and XM antennas? My GPS will "lose signal" without apparent reason and the XM didn't work at all. Both are mounted in the nose of a Long EZ. Thanks for any advice.
DRV

[John Slade]

I have the 196 with the antenna stuck up inside the nose above the rudder pedals. No problems here. Maybe you have a bad connection to or inside the antenna.

[SteveWrightNZ]

has it always been bad, or just started playing up ?

check that the antenna plug is fully seated.

make sure the connector is completely moisture free

can you borrow another antenna and/or cable to try ?


hth,
S

[MSires]

I have a 396, but only use it as a portable - for the GPS I usually just use the one that mounts on the unit, and the XM antenna is tossed on the dash of either the plane or car I'm in at the moment. I haven't had any issues with GPS or XM reception (except in tunnels in the car ). If the unit works fine with the unit mounted antenna for the GPS, but the one in the nose doesn't, I'd check the cabling to make sure it didn't get damaged somewhere on the path from the instrument panel to the antenna.

Mark

[Lynn Erickson]

Originally Posted by rviglierchio

Am using a Garmin 396 and seem to have antenna problems. Is anyone using these finding it difficult to locate the GPS and XM antennas? My GPS will "lose signal" without apparent reason and the XM didn't work at all. Both are mounted in the nose of a Long EZ. Thanks for any advice.
DRV

Any metal or carbon fiber above the antenna? is there any wire screen in the top surface for a transponder antenna ground plane? transponder antenna near by the gps antenna? if not remove the antenna and hold above the nose on the outside. and you must be outside if the hanger has a metal roof.

[rviglierchio]

More info on the issue: I could not seem to get any weather on the unit and have not tried it on the ground with the XM antenna in the nose. Will do so when I get back out to the plane (it's the one with crunched nose gear from RR). The GPS antenna worked just fine for a few hours than "lost signal" for 10 -15 minutes just when I needed it most, then came back on line. It did this more than once. I have nothing above them other than composite (no carbon) and fasteners. I'm wondering if the magnet on the XM has anything to do with it and what it might affect near the back of the panel. The A&P mounted it pretty close to the radios and it didn't seem to bother anything....
Am talking to Garmin and so far they have been helpful and interested in a solution, which I didn't expect from a big outfit like that. Much more customer friendly than the Lowrance company. I finally put their product in a drawer. Thank you all for the advice and tips to look into!
DRV

[jsbougher]

Hey, you ever get an answer to this??

I've had much the same experience. I have a Garmin 430 and my dad has a 496 I borrow on occassion. On one occasion (Florida to Ohio) I lost GPS signal on 496 after about 2 hours of flight. I was only using built-in antenna and moved GPS over to window. If I held in particular spot (above door handle on East facing window), I'd get a signal back, but was still weak and on-off-on. Finally, signal came back strong and I could put back in my lap (plane is a std Velocity so not much metal in sight).

On a different occasion (Indianapolis to Cleveland) I had something even more strange happen. Tooling along fat, dumb and happy on autopilot and all of a sudden the plane starts an uncommanded turn. I look at GPS (Trutrak ADI) and it says no GPS signal. I look at 430 and it agrees - no GPS signal. I look at the 496 and it agrees - no GPS signal.

Now I've had spotty GPS signal from 430 on occasion in past but I chaulked up to wiring issue I'd get addressed before getting IFR ticket. But here, I lost both hand-held and panel mount at same time??? I called ATC and asked if there were any known problems in this area or at this time. They sounded pretty befuddled by the question and said no.

So, I figure I either happened into a dead spot / sun flare / undertermined gremlin, or maybe I have a static problem??? The 430 in particular seems to only have issues after a few hours of flight. The 2 times I've had problem with 496 were also after several hours of flight. Heck, at home I can use the 496 in the house some times and get GPS signal (no FM without antenna outside).

Any thoughts?

[Waiter]

I'm curious, what are you usiing for a transponder antenna?

Waiter

[rviglierchio]

My problem turned out being the antenna. They sent me a new one that has never failed. Now, occasionally, the 396 can't seem to find itself if not used for several weeks. One has to play around with it to get it going again. All else is good. Enjoying the plane immensely.
Dave

[jsbougher]

Originally Posted by Waiter

I'm curious, what are you usiing for a transponder antenna?

Waiter

To be honest, I really don't know. I've relocated to China and the plane is in storage in the US for now. I've been debating as to whether I should have an avionics tech check this issues as well as poor radio transmit ability (always receives well).

Why do you ask about transponder antenna??

[MSires]

For those wondering about losing GPS signal.

Did you check the NOTAMS for your flight path before you went flying like all good pilots do? I frequently see NOTAMS for weak or inaccurate GPS signal for specific areas. I don't know if this is because of limitations in the system, or if they are testing some GPS jammer (tin foil hats at ready!), but it is fairly common.

Mark

[MSires]

Now, occasionally, the 396 can't seem to find itself if not used for several weeks. One has to play around with it to get it going again.

The Garmin units 'remember' where they were when turned off. They use this to optimize their search for satellites when they are turned back on. If they are moved long distance while off (like, say in my carryon during a commercial flight from Florida to California, which is how I discovered this), or are off long enough that they lose that memory, they take a REALLY LONG time to find themselves in the world again. You can shorten this significantly by going to the setup menu and telling it where it is.
Mark

[argoldman]

Originally Posted by MSires

The Garmin units 'remember' where they were when turned off. They use this to optimize their search for satellites when they are turned back on. If they are moved long distance while off (like, say in my carryon during a commercial flight from Florida to California, which is how I discovered this), or are off long enough that they lose that memory, they take a REALLY LONG time to find themselves in the world again. You can shorten this significantly by going to the setup menu and telling it where it is.
Mark

Mark, I don't know if they loose their memory so much as think that they are in the old location and are looking for satellite configurations for that location They have tables which tell them where the satellites should be, given the time, and when what they are getting makes no sense, they look until they find the combination that makes sense to them for general location. The speed of location may depend on where on their lookup list your location sits.-- at least I think that is how it works.

[Brian DeFord]

Interesting reading about the x96 GPS units and loss of GPS signal...I've been flying a Light Sport CTSW the past few months and just ferried one up to Idaho from Arizona this past weekend. That one had a 396 installed and on a familiarization flight across town the first time I took it up the GPS was fine until about 1500' in the air. No GPS signal! But then it comes back on as I get ready to land. Strange. Same thing when I took off again. So I figured something was up and started to research the issue. The antenna in this plane was a remote passive antenna - cost about $20. The Garmin recommended antenna is an active antenna with a suggested retail of $100. I suspect that the passive antenna is good enough when you are close to the ground like when you use it in car, but deteriorates as you get higher or have weaker signals. I found the active antenna for $68 at Cabella's Sporting Goods store and took it on a test flight. No problems. Worked flawlessly from AZ to Boise and up to 11,500 ft altitudes. I'm no radio expert, but I really suspect that a good ground plane might allow the active antenna to work acceptably in a composite plane. Then again, I could be all wet. I'm all for inexpensive solutions but I didn't have the luxury of time in this particular case to explore the ground plane option.

[David Staten]

Originally Posted by Brian DeFord

I suspect that the passive antenna is good enough when you are close to the ground like when you use it in car, but deteriorates as you get higher or have weaker signals.

Given that GPS is a space based, not a ground based navaid, this theorization just doesn't make sense. Signals should be (ever so slightly) stronger the higher you climb.