Garmin GpsMap 396 - Flight Test

[Mike Spera]

Made it up in the air today. Scattered cells and rain all over the
place. Mostly, moving out and clearing. 30 seconds after take off, lost
the GPS sat lock. Took about 15 seconds to regain it. In the next 5
minutes, it lost lock several more times. I'm thinking, external antenna
is loopy. I hooked up the stubby one and it still failed on and off. I
switched to the satellite page and watched all the levels go wildly up
and down. WAAS signal was up and down, mostly down. My previous 2 GPS
units (one circa 1995) NEVER did this. On one 4 mile stretch, the signal
was down to zero and stayed there. Nothing. Zilch. Turns did not really
affect the performance. After about 15 more minutes of flying, it
settled down to a more "normal" pattern. Several sats were at the top
level and several more were 3/4 up and moving about just a little. Once
settled down, turns made a big difference. As some were lost, others
gained strength.

All during the events, the WX signal kept up fine. When it did lock
(about 50 out of 55 flight minutes), the weather display was EXACTLY
what I wanted to see. Rain intensity and direction. This was the
specific day I would use this unit for.

All looked to be in sync until landing. Again, I watched the sat signals
all march towards zero, however, they quickly recovered before losing lock.

I'm thinking this unit has an internal antenna connection defect. I'll
try it out again in the next few days and see whether it is going back
to the dealer.

Not exactly confidence inspiring. This unit may be a bad one. It
happens, I just wish it were a complete failure instead of this
intermittent crap.

I'll report on its progress.

Mike

[Dan Luke]

"Mike Spera" wrote:

> I'm thinking this unit has an internal antenna connection defect.

Or it could be RF interference from some source in the airplane: the
symptoms sound like it. This is exactly what one of my Cessna ARC-385
radios used to do to my portable GPS. Try tuurning off all emitting devices
one at a time the next time it happens. As a last resort, try turning off
the master. You might also try a new location for the remote antenna.

> I just wish it were a complete failure instead of this intermittent crap.

Amen. I hate gremlins.

--
Dan
C172RG at BFM

[Mike Spera]

I figured it was the remote or its location, even though my last 2 GPS
antennas were placed there with zero loss of signal - ever.

But, I disconnected the remote and put on the stubby (you have to remove
the power plug - another not so great design idea). It still failed in
exactly the same way. So, a different antenna and different location did
not solve the problem.

I don't have enough data yet to make the case for a DOA exchange. Since
the weather today is blotto, I will have to test tomorrow morning or
during the week.

Thanks,
Mike

>>I'm thinking this unit has an internal antenna connection defect.
>
>
> Or it could be RF interference from some source in the airplane: the
> symptoms sound like it. This is exactly what one of my Cessna ARC-385
> radios used to do to my portable GPS. Try tuurning off all emitting devices
> one at a time the next time it happens. As a last resort, try turning off
> the master. You might also try a new location for the remote antenna.
>
>
>>I just wish it were a complete failure instead of this intermittent crap.
>
>
> Amen. I hate gremlins.
>

[Dan Luke]

"Mike Spera" wrote:

> But, I disconnected the remote and put on the stubby (you have to remove
> the power plug - another not so great design idea). It still failed in
> exactly the same way. So, a different antenna and different location did
> not solve the problem.

What was the location of the remote antenna? If it was on the glare shield,
the stub antenna on the yoke wasn't much farther from the radio stack.

> I don't have enough data yet to make the case for a DOA exchange. Since the
> weather today is blotto, I will have to test tomorrow morning or during the
> week.

Yes, it could be an intermittent antenna connection or such in the unit, but
try putting the remote antenna as far back in the airplane as possible and
see what happens. Then try shutting radios, etc. down.

I''ve had no reception problems with my 396 except when using the stub
antenna in the car.

--
Dan
C-172RG at BFM

[Dan[_1_]]

Has anyone noticed the GPS altitude and what the altimeter says become
increasingly different as altitude increases? (i.e. 10-12k+)?

This difference seems much more pronounced the higher I go. (Yes, I do
have the correct altimeter setting...) The GPS always seems to read
250-500 feet higher.

--Dan



Dan Luke wrote:
> "Mike Spera" wrote:
>
> > But, I disconnected the remote and put on the stubby (you have to remove
> > the power plug - another not so great design idea). It still failed in
> > exactly the same way. So, a different antenna and different location did
> > not solve the problem.
>
> What was the location of the remote antenna? If it was on the glare shield,
> the stub antenna on the yoke wasn't much farther from the radio stack.
>
> > I don't have enough data yet to make the case for a DOA exchange. Since the
> > weather today is blotto, I will have to test tomorrow morning or during the
> > week.
>
> Yes, it could be an intermittent antenna connection or such in the unit, but
> try putting the remote antenna as far back in the airplane as possible and
> see what happens. Then try shutting radios, etc. down.
>
> I''ve had no reception problems with my 396 except when using the stub
> antenna in the car.
>
> --
> Dan
> C-172RG at BFM

[Dan Luke]

"Dan" wrote:

> Has anyone noticed the GPS altitude and what the altimeter says become
> increasingly different as altitude increases? (i.e. 10-12k+)?
>
> This difference seems much more pronounced the higher I go. (Yes, I do
> have the correct altimeter setting...) The GPS always seems to read
> 250-500 feet higher.

Your altimeter is not corrected for temperature. The GPS is not affected.

--
Dan
C172RG at BFM

[Dan[_1_]]

This would seem to pose a safety risk in IMC, would it not? Ideally,
wouldn't altimeter settings take this into account?

I assume that since all altimeters will behave this way, ATC obviously
expects me to be at, say 10,500 as indicated by my altimeter, even
though that could be 10,900 or so MSL _actual_ altitide..

Seems a bit sub-optimal somehow... even dangerous.

I never thought the effects were so pronounced....

-Dan


Dan Luke wrote:
> "Dan" wrote:
>
> > Has anyone noticed the GPS altitude and what the altimeter says become
> > increasingly different as altitude increases? (i.e. 10-12k+)?
> >
> > This difference seems much more pronounced the higher I go. (Yes, I do
> > have the correct altimeter setting...) The GPS always seems to read
> > 250-500 feet higher.
>
> Your altimeter is not corrected for temperature. The GPS is not affected.
>
> --
> Dan
> C172RG at BFM

[Dan Luke]

"Dan" wrote:

> This would seem to pose a safety risk in IMC, would it not?

Yes, it could. Extremely low temperatures can be dangerous to low-flying
aircraft because altimeters will read high in such conditions.

> Ideally,
> wouldn't altimeter settings take this into account?

Yes. Also ideally, I would be flying a new Bonanza.

> I assume that since all altimeters will behave this way, ATC obviously
> expects me to be at, say 10,500 as indicated by my altimeter, even
> though that could be 10,900 or so MSL _actual_ altitide..

Yes.

> Seems a bit sub-optimal somehow... even dangerous.

It works fine as long as everyone is using the local altimeter setting.
Watch out near the ground when it's real cold, though.

--
Dan
C172RG at BFM

[Doug Vetter]

Mike Spera wrote:
<snip>
> Not exactly confidence inspiring. This unit may be a bad one. It
> happens, I just wish it were a complete failure instead of this
> intermittent crap.
>
> I'll report on its progress.
>
> Mike

Funny you should mention this. My 396 GPS reception has been flaky
lately too. Normally, the stick antenna would give me 4-5 sats indoors,
which is pretty good, while the external (powered) antenna would lock 8+
sats at higher signal indications in the same location (understandable
since it has a preamp that's powered through the coax).

Shortly after I upgraded to firmware 3.0 or 3.1 (can't remember exactly)
I took a trip to SC and had the external antenna just completely crap
out on me. No sat reception at all. I replaced it with the stick and
that got me three sats...enough for 2D positioning.

I initially attributed it to poor satellite positioning (there are times
when all the sats are behind the aircraft and the aircraft structure
shields the yoke/glareshield area), but it didn't comfort me to realize
that the Garmin 430 in the panel was locked to 10 sats with signals
pegged high.

Just today, after upgrading to 3.2, the problem isn't as bad, but the
external antenna doesn't seem to be doing the same job as it used to.

The release notes for the last several releases mention that they've
been screwing with reception issues for the XM receiver, but I wonder if
they messed something up with the GPS component firmware.

So, who wants to open a case with Garmin? If I can find two seconds to
rub together, I just might...this thing WAS running beautifully in the
2.x firmware days. I'm almost tempted to downgrade and test my theory.

-Doug

--------------------
Doug Vetter, ATP/CFI

http://www.dvatp.com
--------------------

[john smith]

You know, with the reception problems I am reading about here, I think I
will stick with my GPS 195 a while longer. I always get a lock with a
minimum of six to eight sats.

[Jonathan Goodish]

In article
>,
john smith > wrote:

> You know, with the reception problems I am reading about here, I think I
> will stick with my GPS 195 a while longer. I always get a lock with a
> minimum of six to eight sats.

I don't have reception problems, and am puzzled as to why some users are
experiencing them. I am using the GA26 remote antenna, but this is
supposedly a "low power" antenna, so I'm not sure if that is a factor or
not (Garmin uses active antennas.) I have an unused GA56 on top of the
airplane, and that does seem to result in stronger signals, but part of
that could be the more ideal placement, with an unobstructed view of the
sky.


JKG

[Dan Luke]

"Jonathan Goodish" wrote:
> >,
> john smith > wrote:
>
>> You know, with the reception problems I am reading about here, I think I
>> will stick with my GPS 195 a while longer. I always get a lock with a
>> minimum of six to eight sats.
>
> I don't have reception problems...

Nor I. I get the same reception performance--or better--with the 396 as I
have with all my previous Garmins.

I do remember that my 195 had trouble locking if activated while in motion.
The 396 is not bothered.

--
Dan
C172RG at BFM

[Mike Spera]

>
> Funny you should mention this. My 396 GPS reception has been flaky
> lately too.

I went out again and tried a few things. I noticed on both days that I
would get 8-10 sats pinned at the top while stationary. Once I started
rolling, most would come down a bit and jump up and down some. After
rotation and climbing, all sats were lost and the thing lost its lock. I
landed and tried again. Same result. O.K. So I cannot depend on it
during a climb?

Next, I tried moving the antenna around and switching to the stub. It
seemed a little better placing the antenna on the right side of the
glareshield opposite the XM. Turning in some directions made for better
or worse reception. However, WAAS was lost going some ways and regained
randomly along that path or by turning. This seems flaky.

Then I tried something I never really tried with my other GPS units. I
watched the sat page while transmitting. All sat bars marched down to
the bottom and disappeared in about 5-7 seconds. Release the transmit
button and they immediately came back up to where they were. So, now I
cannot trust this thing while transmitting?

I will bring along my Lowrance Airmap 1000 and monitor the sat page
during the various aspects of flight and compare it to the Garmin.
Perhaps the Lowrance is just as weak and I did not notice (because it
never lost a lock so I had no reason to look). For laughs, I may also
bring along one of my several Apollo 920 units and watch its
performance. The Apollo never lost its lock in 7 years of use.

Mike

[Dan Luke]

"Mike Spera" wrote:

>
> Then I tried something I never really tried with my other GPS units. I
> watched the sat page while transmitting. All sat bars marched down to the
> bottom and disappeared in about 5-7 seconds. Release the transmit button
> and they immediately came back up to where they were. So, now I cannot
> trust this thing while transmitting?

It could still be you have a faulty 396, but it sounds like it's you have a
radio/electrical problem. I had a Cessna NAV/COM that did the same thing to
my old 295. Swapping the radio with another one solved the problem. You may
also have a leaky antenna cable shield.

Is that the only COM radio you have? What happens when you power it off and
use another transmitter? If the same thing happens, you may have a
grounding problem in the airplane.

Trying the other portable GPS is a good test. If you're lucky, the Lowrance
will work ok and prove you have a bad Garmin. If not, I still recommend
that you turn off EVERYTHING electrical in the airplane and see how the 396
receives satellites. Then, add stuff back in one at a time until you
observe any loss of signal.

Good luck with your gremlin.

--
Dan
C172RG at BFM

[Jonathan Goodish]

In article >,
Mike Spera > wrote:
> Then I tried something I never really tried with my other GPS units. I
> watched the sat page while transmitting. All sat bars marched down to
> the bottom and disappeared in about 5-7 seconds. Release the transmit
> button and they immediately came back up to where they were. So, now I
> cannot trust this thing while transmitting?


COM will interfere with GPS signal. Try relocating the antenna, or
re-routing the antenna cable. You could probably temporarily suction
the antenna to a rear window, or do some tests on the ground with the
antenna on top of the cabin.



JKG

[Jonathan Goodish]

In article >,
"Dan Luke" > wrote:
> > I don't have reception problems...
>
> Nor I. I get the same reception performance--or better--with the 396 as I
> have with all my previous Garmins.

In Mike's case, it sounds like an interference issue to me.


JKG

[Denny]

Very possible... He needs to get out of the airport area and turn off
thenav/com radios and the transponder and see what happens... If that
is no good, then turn off the master switch and the alternator... If
still no good, then it is the 396...

denny

[Mike Spera]

Actually, I did try a few tests. When switching to my second com and
transmitting, it did the same thing. Down to zero on every sat.
Relocating the GPS antenna to the back seats near the window or anywhere
else made no difference when transmitting. It did seem a little better
for reception on the right side of the glareshield (opposite side from
the XM antenna). Turning off all the radios and the complete electrical
system had no effect. I still had flaky reception.

Once I have my other GPS units side by side with this one, I should be
able to isolate whether it is a plane/radio or specific GPS problem.

Thanks to all for suggestions,
Mike

> Very possible... He needs to get out of the airport area and turn off
> thenav/com radios and the transponder and see what happens... If that
> is no good, then turn off the master switch and the alternator... If
> still no good, then it is the 396...
>
> denny
>

[Dan Luke]

"Mike Spera" wrote:
> Turning off all the radios and the complete electrical system had no
> effect. I still had flaky reception.

Now it really sounds like you have a bad 396.

> Once I have my other GPS units side by side with this one, I should be
> able to isolate whether it is a plane/radio or specific GPS problem.

That will be interesting.

--
Dan
C172RG at BFM

[[email protected]]

Mike Spera wrote:
>30 seconds after take off, lost
> the GPS sat lock. Took about 15 seconds to regain it. In the next 5
> minutes, it lost lock several more times. I'm thinking, external antenna
> is loopy.


Mike,

For what its worth...

I just flew my Arrow around the country and experienced the same
problem (with my brand spank'n new 396) that you described. Most of the
occurrences were in the takeoff or landing phase of the flight. I had
my old Lowrance airmap 100 on the copilot yoke and it never lost lock
once during the flight. The 396 was connected to the remote antenna
which was sitting on the glare shield, the airmap 100 was using it's
built in antenna.

-Bernie

My fly-about <http://www.iperformax.com/flyabout/flyabout.html>

[Mike Spera]

> Mike Spera wrote:
>
>>30 seconds after take off, lost
>>the GPS sat lock. Took about 15 seconds to regain it. In the next 5
>>minutes, it lost lock several more times. I'm thinking, external antenna
>>is loopy.
>
>
>
> Mike,
>
> For what its worth...
>
> I just flew my Arrow around the country and experienced the same
> problem (with my brand spank'n new 396) that you described. Most of the
> occurrences were in the takeoff or landing phase of the flight. I had
> my old Lowrance airmap 100 on the copilot yoke and it never lost lock
> once during the flight. The 396 was connected to the remote antenna
> which was sitting on the glare shield, the airmap 100 was using it's
> built in antenna.
>
> -Bernie
>
> My fly-about <http://www.iperformax.com/flyabout/flyabout.html>
>
Too early to reach a conclusion. As I said, I will try the Airmap 1000
and Apollo 920 side by side with the Garmin and see if I can isolate it.

At least I don't feel quite so crazy since yours does it too. Funny
thing, I never mentioned any problems in landing in my post, but it did
indeed almost lose its lock in both descents I made during testing. I
had maybe 2 sats at minimal strength for 30 seconds or so one time.
Another descent had the thing completely checking out for 1 full minute
(no sats at all).

Thanks,
Mike



Thanks,
Mike

[Jim Carter[_1_]]

An off the wall thought - you lose lock and signal during periods of
high-rpm (takeoff and climbout) and low-rpm (landing), but mid-range
seems to work okay. Could there be some hypersensitivity to voltage
fluctuations that the 396 has? Voltage might also drop during
transmitting if there is a resistance in the bus supply.

You've moved the antenna, around and even switched back and forth
between powered external and stubs. If it isn't the 396 then what other
common denominators are there? (Even if it is voltage fluctuation, the
396 shouldn't be that sensitive -- none of your other avionics are.)



> -----Original Message-----
> From: Mike Spera ]
> Posted At: Tuesday, July 04, 2006 14:17
> Posted To: rec.aviation.owning
> Conversation: Garmin GpsMap 396 - Flight Test
> Subject: Re: Garmin GpsMap 396 - Flight Test
>
>
> > Mike Spera wrote:
> >
> >>30 seconds after take off, lost
> >>the GPS sat lock. Took about 15 seconds to regain it. In the next 5
> >>minutes, it lost lock several more times. I'm thinking, external
antenna
> >>is loopy.
> >
> >
> >
> > Mike,
> >
> > For what its worth...
> >
> > I just flew my Arrow around the country and experienced the same
> > problem (with my brand spank'n new 396) that you described. Most of
the
> > occurrences were in the takeoff or landing phase of the flight. I
had
> > my old Lowrance airmap 100 on the copilot yoke and it never lost
lock
> > once during the flight. The 396 was connected to the remote antenna
> > which was sitting on the glare shield, the airmap 100 was using it's
> > built in antenna.
> >
> > -Bernie
> >
> > My fly-about <http://www.iperformax.com/flyabout/flyabout.html>
> >
> Too early to reach a conclusion. As I said, I will try the Airmap 1000
> and Apollo 920 side by side with the Garmin and see if I can isolate
it.
>
> At least I don't feel quite so crazy since yours does it too. Funny
> thing, I never mentioned any problems in landing in my post, but it
did
> indeed almost lose its lock in both descents I made during testing. I
> had maybe 2 sats at minimal strength for 30 seconds or so one time.
> Another descent had the thing completely checking out for 1 full
minute
> (no sats at all).
>
> Thanks,
> Mike
>
>
>
> Thanks,
> Mike

[Dan[_1_]]

I picked up a 396 on Friday and it was fine all the way from Phoenix to
Santa Fe, but lost it's sat signal during landing in Chandler....
Strange, but it seems I am not alone.


--Dan


wrote:
> Mike Spera wrote:
> >30 seconds after take off, lost
> > the GPS sat lock. Took about 15 seconds to regain it. In the next 5
> > minutes, it lost lock several more times. I'm thinking, external antenna
> > is loopy.
>
>
> Mike,
>
> For what its worth...
>
> I just flew my Arrow around the country and experienced the same
> problem (with my brand spank'n new 396) that you described. Most of the
> occurrences were in the takeoff or landing phase of the flight. I had
> my old Lowrance airmap 100 on the copilot yoke and it never lost lock
> once during the flight. The 396 was connected to the remote antenna
> which was sitting on the glare shield, the airmap 100 was using it's
> built in antenna.
>
> -Bernie
>
> My fly-about <http://www.iperformax.com/flyabout/flyabout.html>

[Dan[_1_]]

By the way, this was with firmware version 2.8 which is what came on
the unit. I am planning to upgrade to 3.2 soon.

--Dan


Dan wrote:
> I picked up a 396 on Friday and it was fine all the way from Phoenix to
> Santa Fe, but lost it's sat signal during landing in Chandler....
> Strange, but it seems I am not alone.
>
>
> --Dan
>
>
> wrote:
> > Mike Spera wrote:
> > >30 seconds after take off, lost
> > > the GPS sat lock. Took about 15 seconds to regain it. In the next 5
> > > minutes, it lost lock several more times. I'm thinking, external antenna
> > > is loopy.
> >
> >
> > Mike,
> >
> > For what its worth...
> >
> > I just flew my Arrow around the country and experienced the same
> > problem (with my brand spank'n new 396) that you described. Most of the
> > occurrences were in the takeoff or landing phase of the flight. I had
> > my old Lowrance airmap 100 on the copilot yoke and it never lost lock
> > once during the flight. The 396 was connected to the remote antenna
> > which was sitting on the glare shield, the airmap 100 was using it's
> > built in antenna.
> >
> > -Bernie
> >
> > My fly-about <http://www.iperformax.com/flyabout/flyabout.html>

[Mark Hansen]

On 07/03/06 17:59, Doug Vetter wrote:
> Mike Spera wrote:
> <snip>
>> Not exactly confidence inspiring. This unit may be a bad one. It
>> happens, I just wish it were a complete failure instead of this
>> intermittent crap.
>>
>> I'll report on its progress.
>>
>> Mike
>
> Funny you should mention this. My 396 GPS reception has been flaky
> lately too. Normally, the stick antenna would give me 4-5 sats indoors,
> which is pretty good, while the external (powered) antenna would lock 8+
> sats at higher signal indications in the same location (understandable
> since it has a preamp that's powered through the coax).
>
> Shortly after I upgraded to firmware 3.0 or 3.1 (can't remember exactly)
> I took a trip to SC and had the external antenna just completely crap
> out on me. No sat reception at all. I replaced it with the stick and
> that got me three sats...enough for 2D positioning.
>
> I initially attributed it to poor satellite positioning (there are times
> when all the sats are behind the aircraft and the aircraft structure
> shields the yoke/glareshield area), but it didn't comfort me to realize
> that the Garmin 430 in the panel was locked to 10 sats with signals
> pegged high.

Uhhhh, but where is the antenna for the GNS 430 mounted?
.... it's not near the yoke/glareshield, right?

>
> Just today, after upgrading to 3.2, the problem isn't as bad, but the
> external antenna doesn't seem to be doing the same job as it used to.
>
> The release notes for the last several releases mention that they've
> been screwing with reception issues for the XM receiver, but I wonder if
> they messed something up with the GPS component firmware.
>
> So, who wants to open a case with Garmin? If I can find two seconds to
> rub together, I just might...this thing WAS running beautifully in the
> 2.x firmware days. I'm almost tempted to downgrade and test my theory.
>
> -Doug
>
> --------------------
> Doug Vetter, ATP/CFI
>
> http://www.dvatp.com
> --------------------



--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

[Dave Butler[_1_]]

Dan Luke wrote:
> "Mike Spera" wrote:
>
>
>>I'm thinking this unit has an internal antenna connection defect.
>
>
> Or it could be RF interference from some source in the airplane: the
> symptoms sound like it. This is exactly what one of my Cessna ARC-385
> radios used to do to my portable GPS. Try tuurning off all emitting devices
> one at a time the next time it happens. As a last resort, try turning off
> the master. You might also try a new location for the remote antenna.

The garmin 196 I had before the 396 used to lose lock whenever my KX-155 was
tuned to certain VOR frequencies.

[Dave Butler[_1_]]

Dan Luke wrote:
> "Jonathan Goodish" wrote:
>
>,
>>john smith > wrote:
>>
>>
>>>You know, with the reception problems I am reading about here, I think I
>>>will stick with my GPS 195 a while longer. I always get a lock with a
>>>minimum of six to eight sats.
>>
>>I don't have reception problems...
>
>
> Nor I. I get the same reception performance--or better--with the 396 as I
> have with all my previous Garmins.

ditto.

>
> I do remember that my 195 had trouble locking if activated while in motion.
> The 396 is not bothered.

Yes, the ol' 196 would take noticeably longer to initialize if powered up
somewhere other than where it went to sleep, even a few feet. Not so the 396.

[Mike Spera]

So I set up my other 2 GPS units in the cockpit and put their external
antennas right next to the Garmin. The Lowrance Airmap 1000 and an old
Apollo 920+ showed 5-9 sats up near the 80%. The Garmin showed 8+ sats
pinned at the top and one or two more at 50%. Immediately after liftoff
the Garmin marched down to zero on all sats and lost its lock. The other
2 units stayed strong. The Lowrance got better reception in flight than
on the ground.

After leveling, the Garmin reacquired a lock. 10 seconds later, WAAS
locked. Hit the transmit button and the Garmin again marched down to
zero on all sats and immediately popped back up when the mic button was
released. The 2 old units never blinked the entire time during
transmission.

Take up a SE heading, the Garmin goes to zero on all sats and stays
there until I turn to some other direction. The other 2 units keep a
strong lock.

Tried every possible position in the cabin and the Garmin still blanked
out. The other 2 had different sat bars but never went below 80% with 6+
sats. Unplugged all units from ships power and tried the tests on
batteries. Same result. Flew outside the Mode C veil and shut off the
electrical system. Same results. Tried different power settings and it
did not seem to make any difference

When powered back for landing with the nose pushed over, the Garmin
again went out to lunch. The other 2 remained locked and strong.

Brought the whole box o' stuff back to JA Air center after calling them
to obtain agreement for a swap. They swapped the unit and external
antenna and kept the rest of the accessories for the new unit. Made
sense. They did try to talk me into upgrading the software before
agreeing to a swap. I said I would upgrade AFTER we swapped if the
problem remained. After the swap, I would have confidence it is not one
particular bad unit. So, I am not chasing a gremlin that turns out to be
a defective unit.

I would love to go up tonight and try the new unit, however, the
President found it necessary to bung up not one, but 2 30 MILE TFRs FOR
HIS FREAKIN BIRTHDAY PARTY! FOR 24 HOURS! Lovely.

I never did check the SW level of the old unit. I missed that one bit of
data. I will try the new one and check the SW level. If it performs like
the old one, I will upgrade and try again. If it still does not work
after the upgrade, I'll give Garmin a call before taking the unit back
for a refund.

I really d0 love the weather data. I am hoping I can find the gremlin
and keep it.

Will report back late Friday or Saturday.

Mike

[Dan[_1_]]

I inquired to Garmin Tech support about our problems and got the
following response about clearing the almanac. Probably worth a shot.

--Dan


========================
Problem:
I had a problem with satellite reception over the weekend. In
disucssing this with other GPSMAP 396 users, including one who recently
upgraded to firmware 3.20, it seems they are experiencing similar
problems as well.
(i.e. intermittent GPS satellite loss) I have a GPSMAP 195 and have
never had a satellite signal issue. Is this a known problem? Will there
be a firmware fix?
===============================
Thank you for contacting Garmin.

As the GPS uses a satellite almanac of data to track the satellites,
corruption of this almanac will cause the unit to drop the satellite
signals. To correct(erase) the almanac, turn the unit off. Press and
hold the OUT button while turning the GPS on. When the GPS powers on,
release the buttons and let it acquire the satellite signals to start
rebuilding the almanac.

If you have any other questions, please let me know.

Best Regards

===================
Thanks. Would this likely resolve intermittent outages, or is this
only in the case of being completely unable to get a satellite lock at
all?

--Dan

================
Thank you for contacting Garmin.

As the unit contains data on all of the satellites and cycles between
all ones available, corruption of even one satellite's data could cause
the unit to have brief outages as it cycles through the list.

If you have any other questions, please let me know.

Best Regards
















Dan wrote:
> By the way, this was with firmware version 2.8 which is what came on
> the unit. I am planning to upgrade to 3.2 soon.
>
> --Dan
>
>
> Dan wrote:
> > I picked up a 396 on Friday and it was fine all the way from Phoenix to
> > Santa Fe, but lost it's sat signal during landing in Chandler....
> > Strange, but it seems I am not alone.
> >
> >
> > --Dan
> >
> >
> > wrote:
> > > Mike Spera wrote:
> > > >30 seconds after take off, lost
> > > > the GPS sat lock. Took about 15 seconds to regain it. In the next 5
> > > > minutes, it lost lock several more times. I'm thinking, external antenna
> > > > is loopy.
> > >
> > >
> > > Mike,
> > >
> > > For what its worth...
> > >
> > > I just flew my Arrow around the country and experienced the same
> > > problem (with my brand spank'n new 396) that you described. Most of the
> > > occurrences were in the takeoff or landing phase of the flight. I had
> > > my old Lowrance airmap 100 on the copilot yoke and it never lost lock
> > > once during the flight. The 396 was connected to the remote antenna
> > > which was sitting on the glare shield, the airmap 100 was using it's
> > > built in antenna.
> > >
> > > -Bernie
> > >
> > > My fly-about <http://www.iperformax.com/flyabout/flyabout.html>

[Denny]

Awwww right! I learned something here.. Who says Usenet is useless...

denny

[john smith]

In article . com>,
"Dan" > wrote:

> Press and hold the OUT button while turning the GPS on.

What is the OUT button? (Is that one of the ZOOM buttons?)

[Dave Butler[_1_]]

john smith wrote:
> In article . com>,
> "Dan" > wrote:
>
>
>>Press and hold the OUT button while turning the GPS on.
>
>
> What is the OUT button? (Is that one of the ZOOM buttons?)

Yes, one is labeled "IN" and the other one is "OUT".

[[email protected]]

Dan wrote:
> I inquired to Garmin Tech support about our problems and got the
> following response about clearing the almanac. Probably worth a shot.


Dan,

I spoke with Garmin today and got the same reply today. I followed the
procedure to reset the almanac and it took maybe 20 minutes to
complete. I also discussed a problem I am have having with my
lightspeed thirty 3Gs where I get a squeal through the headset when
attached to the 396 when the 396 is plugged in to the cig. lighter.

The support guy suggested I try a ground loop isolator between the 396
and the headset battery box. He mentioned RadioShack, but theirs does
not natively support the 3.5mm (1/8 inch) jack (RS requires a cable
adaptor). I did find a product at crutchfield.com ( 127SNI135 PAC
SNI-1/3.5 Minijack Ground Loop Isolator) that has female / male 3.5 mm
jacks. They web site has 5 testimonials, 2 from 396 owners, asserting
it solved all problems with using the 396's XM radio in the cockpit. I
ordered one today for about $18.00 + $6 shipping. I'll post a reply
next week with the result, but it looks promising.

-Bernie

[darthpup]

GPS units need to have a "quadrifilar" design antenna or they will not
work well.
I had an older Garmin that I connected to an older stock GPS antenna
outside the Cherokee and it still would not work reliably. There is
information on this design antenna on the web. Magellan uses the quad.
http://www.qsl.net/n8imo/qha_4.html

[[email protected]]

wrote:
> Dan wrote:
> > I inquired to Garmin Tech support about our problems and got the
> > following response about clearing the almanac. Probably worth a shot.
>
>
> Dan,
>
> I spoke with Garmin today and got the same reply today. I followed the
> procedure to reset the almanac and it took maybe 20 minutes to
> complete.

I flew today with the newly rebuilt almanac and had no loss of sat.
lock in 2 hours of flying. The GPS page showed much better reception
then before. The almanac rebuild looks like it has had a positive
effect on GPS performance.

-Bernie

[RST Engineering]

You are either funning us, or you have absolutely no idea what a quadrifilar
antenna is. A two foot high antenna mounted on a 6 foot high mast isn't
going to mount easily on anybody's airplane, let alone a homebuilt.

Your "older Garmin ... connected to an older stock GPS antenna" probably
didn't have an amplifier in the antenna with enough gain to overcome the
loss in the coax you used.

Most GPS external antennas use a modified patch antenna with a 25-30 dB
amplifier mounted to the backside of the patch.

Jim


"darthpup" > wrote in message
oups.com...
> GPS units need to have a "quadrifilar" design antenna or they will not
> work well.
> I had an older Garmin that I connected to an older stock GPS antenna
> outside the Cherokee and it still would not work reliably. There is
> information on this design antenna on the web. Magellan uses the quad.
> http://www.qsl.net/n8imo/qha_4.html
>

[john smith]

In article >,
"RST Engineering" > wrote:

> You are either funning us, or you have absolutely no idea what a quadrifilar
> antenna is. A two foot high antenna mounted on a 6 foot high mast isn't
> going to mount easily on anybody's airplane, let alone a homebuilt.

Jim, have you ever seen the GPS antenna for the Goodyear Blimps?
Of course not! Do you think they want everyone to know they have a two
foot high quadrifiler antenna mounted on a six foot mast buried in the
middle of the envelope?