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  #1  
Old 07-08-2014, 10:47 AM
LettersFromFlyoverCountry's Avatar
LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Location: St. Paul, MN.
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Default Troubleshooting APRS

I've noticed that since I had the wing tips painted, the APRS no longer seems to be working.

I opened up the wing and checked the Byonics doohickey to be sure it was receiving a GPS signal and blinking every minute or so. But nothing is showing up.

I have the Howell v 1.0 antenna.

Any thoughts on how to troubleshoot this would be appreciated.
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  #2  
Old 07-08-2014, 11:28 AM
Joe Joe is offline
 
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Quote:
Originally Posted by LettersFromFlyoverCountry View Post
Any thoughts on how to troubleshoot this would be appreciated.
Reading between the line here, Bob, it sounds like you suspect either a conductive (e.g. metal-flake) paint is completing the Faraday cage around the antenna in the wingtip or possibly the antenna was damaged when the wingtip was removed for painting.

Substitution is a good way to troubleshoot this equipment in the absence of test equipment. I suggest you substitute an external antenna as it's pretty easy to implement. You could use your VHF COM antenna if that's feasible. Or temporarily install something for APRS.

Here's a picture of my 2m FM "stubby" (a.k.a. "rubber duck" a.k.a. "rubber dummy load") mounted on a BNC bulkhead connector on a wing inspection cover. Mine works about as well as as my Long-EZ (which uses a full-size vertical dipole) and it's relatively inexpensive to undo in case you decide it's not the solution for you.




And if your antenna is not the problem, you can disregard all of the above :-)

73,
Joe, K7JD
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  #3  
Old 07-08-2014, 12:24 PM
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humptybump humptybump is offline
 
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Hi Bob, I would not suspect the paint. I have metallic silver paint with clearcoat. It has not affected my tracker.

Like all radio issues, diagnostics will be trial an error. Testing "in a hangar" will yield poor data.

I'd start by either pulling unit (or the whole plane) out into a clear area and see if the Byonics capture GPS and transmits. Confirm first with the blinking indicator then with a 2m radio tuned to 144.39 (normal frequency for APRS in USA). If those tests are good then move the 2m receiver further and further away - at least 1/2 mile.

Thus will confirm the tracker, GPS, and "Howell" antenna.

If you have the energy, test with the wingtip opened up and if all is good then repeat with everything buttoned up.

The paint is not my first suspicion.
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  #4  
Old 07-08-2014, 01:10 PM
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petehowell petehowell is offline
 
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Default New antenna

Hi Bob,

I have a new batch of antennae we can dip into to eliminate that variable - do you want to meet at SGS tonight to take a look?

If so - send me an email or txt.

We can check your transmission with my mobile rig.
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  #5  
Old 07-08-2014, 02:09 PM
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Bob, I don't even have an external antenna on my spam can, and I get excellent tracks by using a Micro-Trak VHF Antenna V3 magnetically mounted on a washer and eyebolt inside my back window.

If you don't have access to one of these antennae, maybe you can just start troubleshooting by temporarily installing one of your existing antennae inside your airplane. I have a small piece of electrical tape to protect my plexiglass window from the movement of the antenna tip.
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  #6  
Old 07-08-2014, 02:47 PM
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Bill Boyd Bill Boyd is offline
 
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Default Mine quit mysteriously

when the final blew in the MT-8000. Not a visually obvious failure... Allen Lord graciously fixed it for the cost of parts alone. It was still intermittent after that until i got it back inside ad RF tight enclosure to shied it from RF. Now all is good.
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  #7  
Old 07-24-2014, 01:48 PM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Still trying to diagnose this problem but it's confounding us. Or at least... me.

Pete stopped by and confirmed (using the hangar scanner) that the gizmo was sending out bursts, but took the radio back home to double check that it hadn't lost its programming and it hadn't.

He also gave me a new antenna to try.

Put them in today and confirmed that (a) the MicroTrak is getting power (b) it's getting good GPS data (as evidenced by the steady green light on the LED) and (c) it's transmitting (as evidenced by the short red LED and a burst monitored on the hangar scanner).

I figured, "cool," so I buttoned everything up and went flying.

Nothing. Nada.

It's particularly confounding because nothing really changed from March when it was working fine. The only thing that changed was the wing tip got painted but there doesn't seem to be any consensus that this should've changed anything.

The hangar scanner did detect a strong burst that wasn't my APRS radio. It was louder. Mine was a little softer, noticeably so. (might this have been weather data from the field?).

Reading through the instructions, I note reference to the blue screw for "deviation." Not sure what this is or whether it might be worth playing with.

Opinions? I am considering trying a stubby antenna as described above.
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Last edited by LettersFromFlyoverCountry : 07-24-2014 at 01:55 PM.
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  #8  
Old 07-24-2014, 07:06 PM
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petehowell petehowell is offline
 
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Default backup radio

Bob,

Let's try my backup tracker in your plane next week. We can eliminate or implicate one variable, the antenna.

Pete


Quote:
Originally Posted by LettersFromFlyoverCountry View Post
Still trying to diagnose this problem but it's confounding us. Or at least... me.

Pete stopped by and confirmed (using the hangar scanner) that the gizmo was sending out bursts, but took the radio back home to double check that it hadn't lost its programming and it hadn't.

He also gave me a new antenna to try.

Put them in today and confirmed that (a) the MicroTrak is getting power (b) it's getting good GPS data (as evidenced by the steady green light on the LED) and (c) it's transmitting (as evidenced by the short red LED and a burst monitored on the hangar scanner).

I figured, "cool," so I buttoned everything up and went flying.

Nothing. Nada.

It's particularly confounding because nothing really changed from March when it was working fine. The only thing that changed was the wing tip got painted but there doesn't seem to be any consensus that this should've changed anything.

The hangar scanner did detect a strong burst that wasn't my APRS radio. It was louder. Mine was a little softer, noticeably so. (might this have been weather data from the field?).

Reading through the instructions, I note reference to the blue screw for "deviation." Not sure what this is or whether it might be worth playing with.

Opinions? I am considering trying a stubby antenna as described above.
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Cheers,
Pete

Amateur Plane - RV-9A N789PH - 1950+ Hrs
Amateur Radio - KD0CVN
Doggies Delivered - 25+
St. Paul, MN
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  #9  
Old 07-24-2014, 07:18 PM
PaigeHoffart PaigeHoffart is offline
 
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Is your GPS antenna in the wingtip as well? Have you monitored APRS bursts on the scanner with the wingtip installed? Is it setup to only send when a valid position is received? I think metal flake probably would affect your GPS signal more than the APRS signal.

//Break Break//

Adjusting the deviation will change how loud the signal sounds, but too much is not a good thing. It will eventually splatter onto adjacent channels, and may be outside the passband of some receivers. You are also spreading the power out over a larger bandwidth, which reduces effective range. The software should have a configuration mode where you can make it transmit tones to set the deviation.

Paige
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  #10  
Old 07-24-2014, 07:49 PM
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LettersFromFlyoverCountry LettersFromFlyoverCountry is offline
 
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Default

GPS antenna is under the cowl.

Thinking of buying the TinyTrak 4.
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