Help with Micro-Trak 300 needed

I wired a Micro-Trak into the wing tip and have not been able to get it work when installed in the plane. I pulled it, hooked up a 9V transitor battery to it and it worked just fine. Flew 2 flights and it worked just fine with a battery hooked to it.

Thinking it was the connector, I replaced it and hooked it up again. No GPS light. Hooked up the battery and GPS light comes on. This makes no sense.

Sooooo, out comes the volt/ohm meter. Checked the battery terminals via the connector and it had 8.7 volts and verified the polarity. Now I checked the wiring on the plane. Plane off and at the switch in the cockpit, showed 12.2 volts. Connector was 10.8 volts at the wing tip. Polarity of the plug was the same as the battery. It's designed to work on 9-15 volts so this should not be a problem.

What gives????

Webb,
1.5v drop from switch to wingtip is a lot. Any load could drop it well below its operating range. There is a reason for the drop. You need to track that down.
If I read your post correctly, your at 8.7v at the unit plugged into the plane at the wingtip. That is below operating range and probably drops even more when transmitting.
These low voltages are telling you something.

Kahuna said:

Webb,
1.5v drop from switch to wingtip is a lot. Any load could drop it well below its operating range. There is a reason for the drop. You need to track that down.
If I read your post correctly, your at 8.7v at the unit plugged into the plane at the wingtip. That is below operating range and probably drops even more when transmitting.
These low voltages are telling you something.

Click to expand...

8.7 from the transitor battery works the unit. 10.8 from the plane doesn't. I attribute the drop from 12.2 at the cockpit off switch to 10.8 at the wing tip due to resistance of the wire's length since it's a single long wire from the switch to the wingtip.

Only reasonable explaination is the polarity of the plug is switched when I use the plane's connector. Visual inspection and the volt ohm meter tell me that it is correct but it's the only answer I can come up with since the unit doesn't care where the power comes from.

I'll go out there this evening and switch the polarity on the connector. I'll keep my fingers crossed I don't turn the unit into scrap.

I am not sure about that big of a voltage drop. I assume you are checking the voltage when the device is not hooked up. This is essentially an open circuit indicating that the 1.5 Volt drop is happening with very very little current. When youo hook up the micro trak that voltage drop will be magnified with current.

Swapping the polarity of the connectors may indeed solve your problem, but I would not dismiss a voltage drop out of hand, depending on how you are testing the voltage.

BrentHumphreys said:

I am not sure about that big of a voltage drop. I assume you are checking the voltage when the device is not hooked up. This is essentially an open circuit indicating that the 1.5 Volt drop is happening with very very little current. When youo hook up the micro trak that voltage drop will be magnified with current.

Swapping the polarity of the connectors may indeed solve your problem, but I would not dismiss a voltage drop out of hand, depending on how you are testing the voltage.

Click to expand...

Was testing an open circuit. Thanks for the clarity. I'll hold my fingers and hope that I don't get some of that smoke stored in the wires to show up when I switch the polarity.

Just a thought ----

Working from a 9v battery at the unit, but not from ship power could also be a ground issue.

You might want to check that out before you switch up the wires.

Played with it again tonight. Polarity is correct. Trasistor battery voltage measured when hooked up was 7.5v and battery voltages when not hooked up was 8.1v.

When I hooked the plane's power to the unit, voltage measured at the connector was 10.8v but when I hooked it up to the unit, voltage measured across the connector was 2.9v. This would make sense as to why it won't work but why the drop when using the plane's power?

Ground return easy enough to test using the taxi light connector. Can even test out the power from it too.

My gut says it's the feed line.

fixed and working

It was the the feed line instead of the ground. Replaced the connector at the source and works fine now.

Now I have a new issue with it. It appears that 300mw is not enough power for the number of receiving stations and the antenna (Pete's J-pole antennas) in the wingtip location. On a 1 hour trip, it was picked up a total of 11 times. At a transmit rate of every 60 seconds, the track flight over Laurel, MS was hit 10 times with one miss in that grouping of signals (alt 6,500 feet). It quit, and then I had 1 more hit near Jackson, MS when I was descending (~3,000 feet). The trip started in Fairhope, AL which is near Mobile and my signal was not detected.

I guess I'll need to add a amp to it some time. Any suggestions for an inexpensive one?

The amp you need is readily available to you here.
Caution...
Your gating pretty good. at ~2.5k' agl your being received over 50miles away.
Just because you see gaps does not mean your systems is not working well.
Gaps can be from all kinds of reasons.
Id hold off Web in doing anything else until you get more data under your belt.
Fly for a while and see how she goes.
Report back.
Best,

Better tonight

Kahuna said:

The amp you need is readily available to you here.
Caution...
Your gating pretty good. at ~2.5k' agl your being received over 50miles away.
Just because you see gaps does not mean your systems is not working well.
Gaps can be from all kinds of reasons.
Id hold off Web in doing anything else until you get more data under your belt.
Fly for a while and see how she goes.
Report back.
Best,

Click to expand...

I had better results this evening. First connection was just out of Jackson a little lower than 3,000. Last connection was approaching into Mobile.

Kahuna - you may be right about the performance. I kept hitting the receiver in Laurel the entire time. Me thinks there may not be many stations in Jackson or Mobile. The return trip was at 5,000.

Got a trip to Shreveport next weekend and another to Naples over Thanksgiving.

For now, I'll leave well enough alone.