COM reception problems

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Pascal
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Re: COM reception problems

Post by Pascal »

Hi Larry,

First of all, I am not an expert at all in avionics. Kindly take my advice below with a grain of salt.

Yes, my problem went away. I sprayed the contacts on the back of the radio including the radio connectors with electrical contact cleaner spray.

And I also sprayed the female contacts that are inside the tray as well. I then re-docked the radio inside its tray, screwed the radio in place and it has been working flawlessly ever since.

This was my COM1, a KLX 125 which I like a lot because the radio frequencies are much more readable than the smaller digits on the KLX 135 (COM2). However, I use COM2 most of the time because I get a better sound reception from it.

I am not an expert by any stretch in these things. Last thing I would do would be to check that the antenna is grounded properly. Did you have the coax connectors replaced on both ends?

Did you try to operate the 430 solely on battery power with all the other avionics off so you can rule out interference from another system in your airplane?

If you could get the avionics shop to swap the 430 with a loaner unit and that unit worked flawlessly, then the problem is your 430, otherwise your 430 is probably fine and the problem is elsewhere (coax connectors, coax cable, antenna ground, antenna, voltage.

I hope you can solve your problem soon!
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1911Tex
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Re: COM reception problems

Post by 1911Tex »

When the engine is off, master on, all instruments active, com is loud and clear.....all grounds under cowl tight....may be the spark plug wiring harness, that will the next step. Thanks.
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1911Tex
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Re: COM reception problems

Post by 1911Tex »

Found the problem! Hard to believe; however, when routinely pulling out of the hanger, the nose of the plane normally faces the tower antenna. Engine off, com is clear and loud. Engine on, warbled, indistinct and hard to hear ground control. Taxi at any angle to the tower antenna or in the air clear and loud thereafter. Discovered reception on the ground when the prop is directly between the tower antenna and com antenna, the prop causes the distortion. Slight angle from line of sight to tower, clear and loud. Purposely put the prop with engine on between tower antenna and com antenna a couple more times...warbled. Took months to figure this stupid but simple and free solution out! Hope this helps someone.
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Pascal
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Re: COM reception problems

Post by Pascal »

Good catch!
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diamondchad
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Re: COM reception problems

Post by diamondchad »

I am having the same problem. I have G1000s. Replaced top antenna, problem still persist..seems it has gotten worse over time.

Any ideas out there?
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diamondchad
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Re: COM reception problems

Post by diamondchad »

Also, when flying at night with the gauge light on: When I key the radio, the pilot side overhead light flickers with my voice intensity while the radio is keyed up.

Avionics guy at shop told me they reseated cards in the rack.

Any ideas?
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Pascal
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Re: COM reception problems

Post by Pascal »

Hi Chad,

Again, I am by no means an avionics expert.

Garmin maintenance manual states that severe corosion may prevent good grounding:
http://static.garmin.com/pumac/G1000:Di ... _DA40_.pdf

DA40-180 maintenance manual, radio troubleshooting section 23-10-00:

http://support.diamond-air.at/fileadmin ... mplete.pdf
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1911Tex
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Re: COM reception problems

Post by 1911Tex »

Also check the metal ground plane panel for security and antenna cable connection, both inside the belly for the com antenna.
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krellis
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Re: COM reception problems

Post by krellis »

I'm sure you have already tried this, but sometimes it the headset plugs that are the issue. Take a fine scotchbrite pad to the plugs, then some contact cleaner and see if that helps. Certainly has helped me on occasion in the past. It's not always the radio or tray contacts.
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Diamond_Dan
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Re: COM reception problems

Post by Diamond_Dan »

Happened to me last year (G1000). Turned out to be the audio panel. Dumb question - did your tech try swapping the radios? For our plane, the problem did not follow the radio. A refurb audio panel fixed the problem.
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