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Transmitter Ground issues

E

egp8111

Well Known Member
Patron
I'm thinking I have a ground issue. When I key the mike to transmit my gauges(Vans steam gauges) all jump around. I'm also getting a lot to static on the radio from my stratux. Any suggestions as the best way to ground a radio? I'm pretty clueless when it comes to radios.

Thanks

Skip
RV-4
NC
 
I’d start by looking at the coax braid/shield. It must be attached to the connectors at both the radio and antenna, and at the antenna must have a good ground path to the metal airframe immediately under the antenna.
 
BobTurner said:
SNIP….and at the antenna must have a good ground path to the metal airframe immediately under the antenna.
Click to expand...
Not exactly correct. The antenna must be “well coupled” to the airframe. As this is RF, the simple zero DC resistance idea is not applicable. Don’t go scrapping off any paint.

To the OPs issue, not enough information to provide any coherent answer. So some questions:
- Is this a new issue or not?
- If you remove the Stratus does the problem go away?
- Have you ever connected an antenna analyzer to the feed line and antenna? If so what are the results?
- Do not overlook the radio tray antenna connection. This can easily create a lot of similar issues if the radio does not properly seat in it. For that matter if it is a 90 degree center wire solder type, look at the cover cap - it might be shorting it out (easy to do if the installer gets carried away with the soldering iron).
- Check the radio breaker. If the terminals are loose this may cause your problem.

Carl
 
Carl Froehlich said:
Not exactly correct. The antenna must be “well coupled” to the airframe. As this is RF, the simple zero DC resistance idea is not applicable…
Carl
Click to expand...

I need to think about this some more. If it’s capacitively coupled won’t there be an undesired phase shift in the ground plane current?
 
Yes if I turn off the stratux the interference stops but the gauges still jump when I transmit

Thanks

Skip
 
egp8111 said:
Yes if I turn off the stratux the interference stops but the gauges still jump when I transmit

Thanks

Skip
Click to expand...
Hi Skip, did you ever solve the meter deflection issue? I have a similar problem transmitting from the GTR 200. It makes only the ammeter go -30 amps and acts as a VU meter when I talk. COAX cable has been re-routed but did not make a difference.
 
FWIW - I used to see this with the gauges in my Mooney 231. Key up on the KY197 or KX165 and all the gauges would sag.

The problem was how the gauges themselves were grounded -- Mooney used a spring loaded "point contact" to ground the gauges to the panel. Removing the point contact and running a dedicated wire (18ga) with proper ring terminal terminations from the cluster gauge assembly to a point on the radio rack resolved the issue.

Not saying it's the same problem, but I would take a hard look at the grounding strategy for your gauges...
 
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