Garmin 496 loss of satellite reception

[Dan Luke]

Three times in the last two weeks, my 496 has lost satellite reception upon
descent below 2000' AGL.

This occurred in three different locations:

The first time was about a week ago, crossing the western shoreline of
Galveston Bay, just south of Ellington field. Moving the amplified antenna
around the glare shield did not help, so I replaced it with the stub antenna
and reception was restored. I presumed the remote antenna was defective,
and used the stub the rest of the trip.

Saturday, I checked the amplified antenna at startup and it seemed fine, so
I decided to use it and monitor its performance. It had strong reception on
at least 10 sat's until I descended for the visual approach to Slidell, LA.
At 1500' I heard the "Satellite reception lost!" warning and saw that all
the bars were depressed to near nothing. A few came back enough to
reestablish position, and the GPS remained "on line" until landing.

The third time was the trip back from Slidell to drop off the Angel Flight
folks at Fairhope, AL. Same scenario: descended below 2000' and satellite
reception was briefly lost.

I plan another trip this coming weekend just to see how repeatable this
problem is, but right now, I'm mystified. Anyone have an idea what could be
causing this? Pressure effect on the antenna housing, perhaps?

--
Dan
C172RG at BFM

[Dan[_1_]]

Dan,

I had ABSOLUTELY the same symptoms with my 396. After much testing, I
narrowed down the failures to when I was close to the ground within
line of site of certain cell-phone towers. (only with the GA25 external
antenna shipped with the unit)

Again, stub antenna worked fine. I contacted Garmin, who sent me
another GA25 antenna (no dice). When I called back, they said that
there have been issues with the GA25 antennas (apparently in the design
iteslf) and sent me a GA26 (the older version, same form factor as the
antenna that came with the GPSMAP 195). So far I believe this will
resolve the issue, but I am planning to test after work today.

Give Garmin a call and ask for a different type of antenna. They'll
even overnight it to you if you tell them you are flying again soon.

--Dan


Dan Luke wrote:
> Three times in the last two weeks, my 496 has lost satellite reception upon
> descent below 2000' AGL.
>
> This occurred in three different locations:
>
> The first time was about a week ago, crossing the western shoreline of
> Galveston Bay, just south of Ellington field. Moving the amplified antenna
> around the glare shield did not help, so I replaced it with the stub antenna
> and reception was restored. I presumed the remote antenna was defective,
> and used the stub the rest of the trip.
>
> Saturday, I checked the amplified antenna at startup and it seemed fine, so
> I decided to use it and monitor its performance. It had strong reception on
> at least 10 sat's until I descended for the visual approach to Slidell, LA.
> At 1500' I heard the "Satellite reception lost!" warning and saw that all
> the bars were depressed to near nothing. A few came back enough to
> reestablish position, and the GPS remained "on line" until landing.
>
> The third time was the trip back from Slidell to drop off the Angel Flight
> folks at Fairhope, AL. Same scenario: descended below 2000' and satellite
> reception was briefly lost.
>
> I plan another trip this coming weekend just to see how repeatable this
> problem is, but right now, I'm mystified. Anyone have an idea what could be
> causing this? Pressure effect on the antenna housing, perhaps?
>
> --
> Dan
> C172RG at BFM

[Dan Luke]

"Dan" wrote:

>
> I had ABSOLUTELY the same symptoms with my 396. After much testing, I
> narrowed down the failures to when I was close to the ground within
> line of site of certain cell-phone towers. (only with the GA25 external
> antenna shipped with the unit)

My 396 never did this. It had the antenna in the same place as the new one.

Still, that would be an explanation that fits the symptoms.

> Again, stub antenna worked fine. I contacted Garmin, who sent me
> another GA25 antenna (no dice). When I called back, they said that
> there have been issues with the GA25 antennas (apparently in the design
> iteslf) and sent me a GA26 (the older version, same form factor as the
> antenna that came with the GPSMAP 195). So far I believe this will
> resolve the issue, but I am planning to test after work today.
>
> Give Garmin a call and ask for a different type of antenna. They'll
> even overnight it to you if you tell them you are flying again soon.

Thanks. Will do.

--
Dan
C172RG at BFM

[Dan[_1_]]

I figured this out by driving around using the external antenna. You
will find places that ALWAYS lose the signal.

These will generally be very open areas with a cell tower about 1/4
mile away. Put a building between yourself and the tower and the
problem disappears.

--Dan


Dan Luke wrote:
> "Dan" wrote:
>
> >
> > I had ABSOLUTELY the same symptoms with my 396. After much testing, I
> > narrowed down the failures to when I was close to the ground within
> > line of site of certain cell-phone towers. (only with the GA25 external
> > antenna shipped with the unit)
>
> My 396 never did this. It had the antenna in the same place as the new one.
>
> Still, that would be an explanation that fits the symptoms.
>
> > Again, stub antenna worked fine. I contacted Garmin, who sent me
> > another GA25 antenna (no dice). When I called back, they said that
> > there have been issues with the GA25 antennas (apparently in the design
> > iteslf) and sent me a GA26 (the older version, same form factor as the
> > antenna that came with the GPSMAP 195). So far I believe this will
> > resolve the issue, but I am planning to test after work today.
> >
> > Give Garmin a call and ask for a different type of antenna. They'll
> > even overnight it to you if you tell them you are flying again soon.
>
> Thanks. Will do.
>
> --
> Dan
> C172RG at BFM

[Dan[_1_]]

Followup... The replacement GA26 antenna works perfect...

--Dan


Dan wrote:
> I figured this out by driving around using the external antenna. You
> will find places that ALWAYS lose the signal.
>
> These will generally be very open areas with a cell tower about 1/4
> mile away. Put a building between yourself and the tower and the
> problem disappears.
>
> --Dan
>
>
> Dan Luke wrote:
> > "Dan" wrote:
> >
> > >
> > > I had ABSOLUTELY the same symptoms with my 396. After much testing, I
> > > narrowed down the failures to when I was close to the ground within
> > > line of site of certain cell-phone towers. (only with the GA25 external
> > > antenna shipped with the unit)
> >
> > My 396 never did this. It had the antenna in the same place as the new one.
> >
> > Still, that would be an explanation that fits the symptoms.
> >
> > > Again, stub antenna worked fine. I contacted Garmin, who sent me
> > > another GA25 antenna (no dice). When I called back, they said that
> > > there have been issues with the GA25 antennas (apparently in the design
> > > iteslf) and sent me a GA26 (the older version, same form factor as the
> > > antenna that came with the GPSMAP 195). So far I believe this will
> > > resolve the issue, but I am planning to test after work today.
> > >
> > > Give Garmin a call and ask for a different type of antenna. They'll
> > > even overnight it to you if you tell them you are flying again soon.
> >
> > Thanks. Will do.
> >
> > --
> > Dan
> > C172RG at BFM

[Jonathan Goodish]

In article om>,
"Dan" > wrote:
> Again, stub antenna worked fine. I contacted Garmin, who sent me
> another GA25 antenna (no dice). When I called back, they said that
> there have been issues with the GA25 antennas (apparently in the design
> iteslf) and sent me a GA26 (the older version, same form factor as the
> antenna that came with the GPSMAP 195). So far I believe this will
> resolve the issue, but I am planning to test after work today.

Ah, perhaps there's the clue. My 396 came with the GA26 antenna, which
is the same antenna that I had with my 195. I noticed that the new 396
and 496 units are shipping with the GA25, which is about half the size
of the GA26. I've never had reception problems with the 195 or 396
using the larger GA26 antenna.


JKG