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alternate location for SV-GPS-2020?

dbhill916

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Hi all,

I'm troubleshooting the GPS puck in my legacy 12 with a dual Dynon setup. The SV-GPS-2020 was installed in 2019 and has worked well until this summer. The position lock has become increasingly flakey over the last few months. It's worse when it's hot outside, but doesn't go away in the cooler fall weather. Loading the data logs onto Savvy's system shows that GPS Fix Quality is typically 1 or 2, but occasionally becomes 0 for a few seconds. The Number of Satellites is generally 6 or 7 with a minimum of 4 and maximum of 9. Looking at SETUP MENU > LOCAL DISPLAY SETUP > GPS FIX STATUS when I'm having poor performance shows that although there may be 8 or 9 satellites in view, the system is often only using 4 satellites and reports Integrity: No. When 5 satellites are in use, Integrity = Yes, and the lock is more robust. The satellites are typically yellow (poor) or white (unusable), but rarely in green (acceptable).

I have reseated the wires & connectors from the SV-GPS-2020 to the AV5000. I have updated the firmware in the SV-XPNDR-262 and the SV-GPS-2020 was fully up to date.

Tech support at Dynon thinks that the location of the GPS puck in the RV-12 is suboptimal as it is essentially shielded by the firewall from the back and this is often further handicapped by conductive (metallic) paint. She recommends repositioning the GPS-2020 to a different location. They are willing to rent me a GPS-2020 for full price (refundable) and $100 and shipping & handling.

Has anyone had this kind of failure mode? Is it reasonable to suspect that the analog receiver circuitry is simply aging and failing? Has anyone moved (or thought about moving) their GPS puck? Has anyone installed a 2nd GPS puck in parallel?

Can interested souls check their SETUP MENU > LOCAL DISPLAY SETUP > GPS FIX STATUS while airborne and provide some data points on how other ships in the fleet are faring? Specifically, I'd like to know what the fleet typically sees with respect to number of satellites that are green, yellow or white when airborne.

Thanks for any advice, comments or commiserations,
-dbh
 
forgot the attachment...
 

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Greeting,
I have attached a screen shot from my MFD, an AdvFlt 5600T screen running the latest software, has the CPU & RAM & SSD updates from 6000 series screen. My SV-GPS-73102 is mounted on aft turtle deck right behind the tippers rear window top position right next to Garmin GPS antenna for GTN650 Xi. The picture is with plane sitting inside finished hangar - drywall ceiling, 20" insulation above between joists, plywood sheathing & composition shingles. Metal bifold door in closed position, aircraft pointed to 209 degrees magnetic with antenna about 8ft from bifold door. In other words - the antenna is somewhat shielded by the building but has always worked very well inside or out.
Is you antenna exposed to engine heat ? (implied by your post re firewall position). It could be your low noise amp or other components inside the puck.... not user serviceable. Possibly borrowing one from Dynon and installing it in the same orig location would tell you if your's is failing... The fact that yours worked for years without issues says that at one time it was healthy... regardless of signal shading. That's one reason I'm curious about heat exposure.
Hope this helps.
 

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Is you antenna exposed to engine heat ? (implied by your post re firewall position).

Yes, in legacy models, the GPS-2050 is on the fire wall, centerline, just under the cowling, See attached from the KAI.

It could be your low noise amp or other components inside the puck.... not user serviceable. Possibly borrowing one from Dynon and installing it in the same orig location would tell you if your's is failing... The fact that yours worked for years without issues says that at one time it was healthy... regardless of signal shading. That's one reason I'm curious about heat exposure.
Hope this helps.

I'm leaning towards heat+age related failure of the analog components. I'm not far from pulling the trigger and just replacing it. If I get a few more data points that don't contradict the hypotheses, then I'll probably just do it.
 

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Forward of the firewall is not a great place to mount a GPS antenna/receiver (the GPS 25O and GPS 2020 have integrated receivers).

End the pain, mount it on your glareshield. I use some dark cloth to cover the antenna/receiver to eliminate glare on the windshield.

Note - do not do this with a Garmin GPS navigator.

Carl
 

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Fwd of firewall, yeah, I fell into that trap🙄. It took a few years & my 2020 antenna failed too - expensive lesson & I’d prefer to have spent that money on avgas instead 😉
 
Fwd of firewall, yeah, I fell into that trap🙄. It took a few years & my 2020 antenna failed too - expensive lesson & I’d prefer to have spent that money on avgas instead 😉
When your GPS-2020 failed, did it just quit or did it exhibit degrading performance over time? Are you flying a --12, and if so, did you relocate it somewhere else?
 
When your GPS-2020 failed, did it just quit or did it exhibit degrading performance over time? Are you flying a --12, and if so, did you relocate it somewhere else?
Degrading was short lived as I do a lot of flying & needed the ADSB In/out capability. Not flying a 12 however you should be able to mount the antenna elsewhere in the 12 ?
 
My RV-12 is exhibiting intermittency as described above. The thermal environment of the mounting location has always bothered me.
 
Yes, in legacy models, the GPS-2050 is on the fire wall, centerline, just under the cowling, See attached from the KAI.



I'm leaning towards heat+age related failure of the analog components. I'm not far from pulling the trigger and just replacing it. If I get a few more data points that don't contradict the hypotheses, then I'll probably just do it.
Maximum operating temperature for the item is 140 deg F. It's a wonder these GPS units function as long as they do. Mine has now failed and I am examining options.
 
I was recently asked to help diagnose a problem with a SV-250 GPS in another aircraft. The SV-250 appeared to be mechanically very similar (identical?) to the SV-2020 in my RV12iS. It transpired that communication with the SV-250 came and went as the wires entering the SV-250 were pulled first one way and then the other.

The owner plans to buy a new SV-250. Where we are the SV-2020 is currently restricted to SIL 0 SDA 0 (the same as the SV-250) so it has no advantage.
 
A previous owner of my legacy RV-12 put the SV-GPS-2020 on top of the rear window, about halfway down. The mounting hardware and wires go through the F-1232A roll bar brace.

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Maximum operating temperature for the item is 140 deg F. It's a wonder these GPS units function as long as they do. Mine has now failed and I am examining options.
Before replacing the malfunctioning unit I disconnected the connector at the end of the 4 wires coming out of the GPS unit. I then reconnected and voila, the GPS is now functioning. I have over 5 hours on the resurrected unit and typically see 9 GPS satellites in use out of 12 visible satellites.
 
I experienced an issue with mine loosing position. Turns out it was the angle of the coax cable coming out of the mount creating a broken connection. Corrected the issue by opening the hole the coax exits the mount and no more issues.
 
Well, the GPS unit finally died. We purchased a new unit and decided to not repeat the mistake of mounting the antenna forward of the firewall. Instead, we chose to mount the antenna within a small cavity forward of the canopy and aft of the firewall and then cover it with a conformal electromagnetic window. My pal, Dan Tracy (RV-7 builder) did the mechanical design and I performed the electrical design. The antenna looks through a 3 layer window consisting of 80 mil plexiglass, 25 mil styrene and 5 mil acrylic. The layers are bonded together with 3M 467 MP adhesive. The outer vinyl layer is of material used for automotive decals and N numbers on aircraft. The performance of the ststem was tested prior to assembly just outside the hangar. Flight testing performance was verified using the FAA ADS-B
 

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