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poor performing APRS

dhall_polo

Well Known Member
I have the following setup in my left wingtip:
- microtrack8000fa
- byonics gps (with the 12to5 dc control board)
- byonics j-pole antenna

Since installing this, I get about 1 hit every few flights or so. So it works, just very badly.
http://aprs.fi/?call=N517DG&mt=roadmap&z=10&timerange=86400

Ideas for debugging appreciated. I'm thinking I need to uninstall it from the wingtip and run it from the cockpit where I can see what the lights are doing. Testing from the ground has proven difficult because I don't get any hits even when all the lights are indicating it is transmitting.
 
PP APRS

Ideas for debugging appreciated.

Don,

The two posits on your aprs.fi plot both were Igated through very close by stations, indicating it's a signal strength issue, and probably an antenna issue at that.

If your airport conditions permit, connect your COM antenna to the tracker (disconnected from the COM radio) and operate NORDO for a short test flight.

If that isn't practical, bring the tracker into the cockpit and use a stubby antenna, a.k.a. "rubber duck", a.k.a rubber dummy load placed near the canopy so it has a view of the horizon (where most Igates are located).

The best RV APRS signals I see come from external antennas. Richard, KE7TUC/N623RS, uses an unmodified COM bent-whip and a 300 mw. tracker with excellent results.

73,
Joe, K7JD
 
I have the following setup in my left wingtip:
- microtrack8000fa
- byonics gps (with the 12to5 dc control board)
- byonics j-pole antenna

Since installing this, I get about 1 hit every few flights or so. So it works, just very badly.
http://aprs.fi/?call=N517DG&mt=roadmap&z=10&timerange=86400

Ideas for debugging appreciated. I'm thinking I need to uninstall it from the wingtip and run it from the cockpit where I can see what the lights are doing. Testing from the ground has proven difficult because I don't get any hits even when all the lights are indicating it is transmitting.

Don, I too suspect you have an antenna problem. It may be as simple as a poor connection or as complex as an overwhelming infestation of the RF gremlins. ;)

The suggestion to try another antenna should isolate the problem for you.
 
Please Clarify

Byonics does not make a " Byonics GPS with 12-5 volt dc control board" or a "Byonics J-pole antenna". Can you describe your antenna? I suspect that for the power supply you mean a Byonics MV-12, which is a 12 volt power supply that is used to power the Micro-Trak; The GPS gets its power from the DB-9 connector on the MT-8000 FA. If by some chance you managed to connect the 12 volt output of the power supply to the GPS directly, it will be dead forever. You are welcome to send the whole system (minus the airplane-UPS would choke) for test and/or repair.

Best regards,

Allen
VHS
p.s. You should know by now that I don't approve of anything left wing!
 
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Howell J pole?

Hi Don,

Do you have one of the Jpoles Ryan and I made? If so, and you think that is the issue, let me know and we can get you a new one.

Yep our recs show it is one of ours. New one is on the way.
 
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Byonics does not make a " Byonics GPS with 12-5 volt dc control board" or a "Byonics J-pole antenna". Can you describe your antenna? I suspect that for the power supply you mean a Byonics MV-12...

Yep meant the 12v regulator. Just bad memory on my part - I installed my aprs long ago but just now getting more determined to fix it. Thanks for sending the new antenna - yes, my whole aprs kit is from byonics, including the antenna. That is incredible service.
 
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Allen
VHS
p.s. You should know by now that I don't approve of anything left wing!

Allen, can you clarify this please? I'm not sure of this is a political joke or a comment against a J-Pole antenna? If so, why?
 
Try turning down the deviation control

My guess is that your deviation is set way too high. My MicroTrak 300 came with the deviation set to MAX. I didn't get any packets digipeated until I turned it down to below half way.

If the deviation is set to high, then the signal gets distorted. The easiest way (short of using a deviation meter) is to listen to 144.39 and set your deviation so that your tracker is no louder than other stations on the air.

The mt8000 has two blue adjustable resistors. the one next to the tracker "chip" controls the deviation. Try turning this one down. The one closest to the antenna connector controls the power. 8 watts is plenty of power when it comes to an airborne tracker. Even if your antenna loses 90% of your power, you shouldn't have any problems reaching an igate or digipeater.

--
Martin
 
Allen, can you clarify this please? I'm not sure of this is a political joke or a comment against a J-Pole antenna? If so, why?

Pete's J-pole antenna is a thing of beauty! There is however a significant downside in efficiency having a cross-polarized antenna ( The VHF world generally has antennae oriented vertically) but even with our flea power transmitter, the MT-300, performance seems to be okay even with this limitation at altitude. A vertically polarized antenna like a belly whip should outperform the J-pole at all altitudes, but I understand your reluctance to add more stuff to the slip stream. One paradigm assumes that you are primarily interested in having friends and loved ones watch your flight in near real time, but as a SAR guy myself, I would like to see your transmitter still active while you are dangling upside down in a redwood tree 200 feet above ground with Avgas running down your neck. ( Not that I am entirely lacking in faith in the next gen ELT's) I don't think wing tips are like earrings, one is for pirates and the other is for, well....... others, so go ahead and install your transmitter and antenna where you can.

FYI, we are looking at a new and more powerful chip that will potentially allow us to change configurations dependent upon altitude. This means we can use a very conservative path at altitude and a more aggressive path at low levels. Next gen transmitters may allow power to be changed as a function of altitude as well. Although this may be of more importance to high altitude balloon launches, it has definite applications in general aviation.

73,

Allen
VHS
 
UPDATE:SUCCESS!

track for N517DG here

With new antenna and adjustments to the PWR potentiometer, I finally had my first successful APRS track!

Some notes:
- My 8000FA doesn't have a pot for DEV adjustment, so I couldn't test Martin's theory. That dev pot looks like a new mod.
- My flight track doesn't show any hits on the ground, but I did get a few hits on the ground when I was testing the new antenna and mucking with PWR adjustments. Unfortunately, I wasn't getting enough reliable hits to adequately test different combinations of PWR and new/old antenna. A full CW setting on PWR with the new antenna got me a couple hits, so I went with that.

This has been on the squawk list for a while, and I'm very glad to check it off. Thanks to Pete and Allen for excellent support, and thanks to all for your comments. Also thanks to Kahuna who's been my primary helper on this from the beginning.

Don
 
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