New 2020 GPS antenae fails in cold temps

[novocaine]

Hi all. First time on the forum. I purchased a plane with the Dynon systems installed. Love both. But had to upgrade the GPS antennae a few months back. Hadn't flown in in very cold temps yet. Yesterday flew and climbed up over the local weather for a XC flight. When OAT it 3 degrees F, GPS source lost and map screen went black with a red x. Flew over the weather for a bit and descended into warmer temps. GPS came back online when temps hit around 35F. Tested it again near my destination airport and same result. On the ground I opened up access and fiddled with all the wires/connectors. No problem there. Stuck a piece of dry ice on the antennae for a few minutes and sure enough, GPS source gone again and black screen. I've reached out to Dynon and waiting to hear back. Anyone ever experience anything like this? Or any ideas what under the plastic in that puck that would cause the GPS source to fail?

the following pics show the wires to the antennae, with no tension on them. A pic of the screen in flight as it's blacked out. My dry ice on the antennae, the screen on the ground after a few min with the dry ice applied. Warming the antennae with my hand, and the screen through the canopy after it's been warmed up. In the first image, you can see there is no gps signal ( inside the hangar) but the source is still there when the antennae is warm. When it froze, the GPS source entirely disappeared.

 

[HFMan]

I've flown down to 20F so far, no issues. Can't say I've been that close to zero however. Would be interested to hear an update from Dynon on this.

 

[maartenversteeg]

Note that the Dynon "GPS antennae" are not just the antenna (like the Garmin 430 systems), but these are actually the complete GPS receivers. These pucks include the receiver circuitry and the digital electronics that lock up with the GSP signal. The data that is relayed to the displays (2 power wires and two serial data lines) consist of pure digital data (GPS coordinates and status information). This receiver and conversion circuitry located in the pucks may be temperature sensitive.

 

[novocaine]

Note that the Dynon "GPS antennae" are not just the antenna (like the Garmin 430 systems), but these are actually the complete GPS receivers. These pucks include the receiver circuitry and the digital electronics that lock up with the GSP signal. The data that is relayed to the displays (2 power wires and two serial data lines) consist of pure digital data (GPS coordinates and status information). This receiver and conversion circuitry located in the pucks may be temperature sensitive.

I wondered how much circuitry existed in the puck. And if there is a lot in there, it may in fact be quite sensitve to temps. I was surprised it was so cold at 11k yesterday, as ground temps were in the 50s. I'm sending in to Dynon to check it over and repair/replace. It would be super to hear if anyone has flown with these at cold temps like this. Or maybe It would be best installed INSIDE the cockpit with a view of the sky?

 

[swatson999]

Getting pretty close to the hairy edge of AFTs there...from the Installation Manual

SV-GPS-2020
Operating Temperature-4°F to +158°F (-20°C to +70°C)

 

[novocaine]

Thank you for finding that. I was looking a bit yesterday for any operating temps but didn't dig deep enough. It's possible that it was just too cold for the unit to function. Has anyone installed this inside the aircraft? Could it be successfully used on top of the panel below the canopy? I think I have seen an antennae there before.

 

[airguy]

I've got mine (three GPS antennae, actually) on a small shelf forward of the firewall and under the cowl, looking up through the fiberglass cowl. Been working flawlessly that way for 4 years and 600 hours so far. One Dynon GPS 2020, one Garmin 430W, and a G5 external antenna.

 

[novocaine]

this is from Dynon tech support in regards to the operating temps:

From the Skyview Installation Instructions : https://dynonavionics.com/public_ht...iew_System_Installation_Guide-Rev_W_v14_0.pdf
SV-GPS-250/2020 Storage Temperature: -40 °C to +70 °C Operating: -40 °C to +60 °C

-40C is pretty cold (it's -40F also) so I'm not sure where you got the info Swatson999. It may be a different version of their specs. I hadn't thought of mounting them under the cowl. I may try that out.

 

[swatson999]

this is from Dynon tech support in regards to the operating temps:

From the Skyview Installation Instructions : https://dynonavionics.com/public_ht...iew_System_Installation_Guide-Rev_W_v14_0.pdf
SV-GPS-250/2020 Storage Temperature: -40 °C to +70 °C Operating: -40 °C to +60 °C

-40C is pretty cold (it's -40F also) so I'm not sure where you got the info Swatson999. It may be a different version of their specs. I hadn't thought of mounting them under the cowl. I may try that out.

That's STORAGE temperature, not OPERATING temperature. Look at Table 111 in the Installation Manual:

Operating Temperature
-4°F to +158°F (-20°C to +70°C)
Storage Temperature
-40°F to +140°F (-40°C to +60°C)

 

[novocaine]

It shows both storage and operating as -40 in what I posted and what the tech sent me. Operating is right after storage in same line

 

[novocaine]

The upper end temperature changes, not the lower end. But ifThey have two different temperatures published, they need to figure out which one is the actual temperature they should be using in their specs. That's a huge difference.

 

[swatson999]

I'm doing a direct cut-and-paste from Revision AF of the Skyview System Installation guide (incidentally more recent than the one the tech sent you), but if you don't want to believe me, you *could* go look in the manual yourself. (ETA: OK, I see the summary table, Table 5, in the manual that does, indeed, say -40...but I was looking at the table of Specs in the section with specs for all the devices...clearly, one or the other is wrong).

For reference, here it is:

 

[RVDan]

I do environmental s testing for avionics. It is somewhat strange that the high storage temp (+60c) would be lower than the high operating temp (+70c). If fact really strange. Perhaps even an error in the spec.

Low operating of -20c sounds right for displays, but not typically for electronics

 

[novocaine]

I have looked, after you posted. I was just sharing what came direct from Dynon as maybe one or the other isnt correct. It's a big difference.

 

[djones]

It does look like we have an error in the documentation and I will need to look into which is correct. I believe the table 111 is in error.
That said we need to replace this one, we have these things flying in all sorts of temps and this is the first I have seen one shutting down
due to cold temps. We will likely be in touch on Monday to take care of this. Our response times are being hampered somewhat right now as
all of support and many others are working remote right now doing our part in the fight against the spread of the COVID 19 virus.

 

[kellym]

It does look like we have an error in the documentation and I will need to look into which is correct. I believe the table 111 is in error.
That said we need to replace this one, we have these things flying in all sorts of temps and this is the first I have seen one shutting down
due to cold temps. We will likely be in touch on Monday to take care of this. Our response times are being hampered somewhat right now as
all of support and many others are working remote right now doing our part in the fight against the spread of the COVID 19 virus.

While the antenna inside the cockpit might stay warm enough, it could never get to the max operating altitude with the antenna on the outside and still work, as the temps would be in the -40 range. I'm sure Don will sort it out as soon as possible, given we all are hunkered down in our bomb shelters.
Kelly

 

[Raymo]

My 2020 and 250 antennas are mounted on the glare shield of my RV-7A but I would not put them there again due to the glare on the windshield. I have them temporarily covered with plans to make fiberglass covers and paint them black, held down by velcro.

 

[swatson999]

I know this is not recommended, but I (and many others) have my GPS antennae (SV-2020 and the Garmin antenna for the 430W) mounted on a shelf, attached to the firewall, under the cowling. They've worked just fine for 750 hours/7 years, and show no signs of any degradation.

 

[owenssonex]

I has issues with my first dynon gps2020 inability to gain a lock at startup. There seemed to be a weak link to solar warming of the antenna helped to gain a lock. Lock time was 20 seconds to 20 minutes. After a few email exchanges and no answers, I had a great call with dynon support to validate my wiring and configuration and an rma was authorized. The replacement GPS2020 antenna is working awesome. Instant locks, zero issues. The new (and old) antenna is mounted on the glare shield of my sonex. Both the old and new antenna are "colored" using a large black sharpie to eliminate windscreen glare. I asked dynon support if this was ok and they said it was ok.

 

[novocaine]

Replacement just tested up to 14k at -5F. No problems!