Radio transmission issue

[Bavafa]

I am helping troubleshoot an issue with a friend and we discovered today that his radio transmission is completely unreadable. He has two radio, Garmin 650 and GRT200. We tried both radio from both pilot and copilot side and all is the same. We do see the TX on the radio so the PTT is working, plus ATC told us it is just static and unreadable. Both antennas are at the belly the standard location for the RV10.

Any thoughts as to what are the possible causes for a poor transmission? I believe it must be something that is common for both radio and the Audio panel (GMA 345) is the only thing common that I can think of. BTW, we hear others just fine without any issue.

 

[Walt]

If you turn off the audio panel it will bypass the internals and xmt/rcv on com 1.

 

[Ralph Inkster]

Review grounding for both radios, intercom. Check headset jacks for chassis grounding. (Including any audio input jacks)

 

[Majorpayne317641]

Is your intercom working fine? If it’s both radios it is more than likely coming from the mic input side between the input jacks and comm panel. It could also be a ground or shielding. Garmin is very particular on how to do both of these. Has it worked in the past? If so then something has to have changed in the wiring.

 

[Bavafa]

Is your intercom working fine? If it’s both radios it is more than likely coming from the mic input side between the input jacks and comm panel. It could also be a ground or shielding. Garmin is very particular on how to do both of these. Has it worked in the past? If so then something has to have changed in the wiring.

This is a new plane to him but he is confident that it was working before. Considering we have tried two different headsets and two different input jack it seems it is unlikely that it would be related to that. Initially I thought the grounding for the antenna, but one would think they would have known this issue and fix it if it was a preexisting condtion.

If you turn off the audio panel it will bypass the internals and xmt/rcv on com 1.

Good suggestion, I will try that.

 

[AZSteve053]

I am helping troubleshoot an issue with a friend and we discovered today that his radio transmission is completely unreadable. He has two radio, Garmin 650 and GRT200. We tried both radio from both pilot and copilot side and all is the same. We do see the TX on the radio so the PTT is working, plus ATC told us it is just static and unreadable. Both antennas are at the belly the standard location for the RV10.

Any thoughts as to what are the possible causes for a poor transmission? I believe it must be something that is common for both radio and the Audio panel (GMA 345) is the only thing common that I can think of. BTW, we hear others just fine without any issue.

Give the Forum folks a fighting chance to help you:
Is this a new problem that just occurred or new installation that never worked ?
How about a block diagram ?
Do the radios receive Ok ?
Affected on ALL frequencies or only particular frequencies
You say ATC says garbled or static - how about other aircraft in the air or on ground nearby ?
Antenna cables - check continuity and for shorts, Check antenna's
Was an avionics shop involved or a home built setup - How about a portion of the wiring diagram
Have you looked at the internal Garmin setup menus for proper configurations ?
Help us Help you....

 

[Bavafa]

Give the Forum folks a fighting chance to help you:
Is this a new problem that just occurred or new installation that never worked ?
How about a block diagram ?
Do the radios receive Ok ?
Affected on ALL frequencies or only particular frequencies
You say ATC says garbled or static - how about other aircraft in the air or on ground nearby ?
Antenna cables - check continuity and for shorts, Check antenna's
Was an avionics shop involved or a home built setup - How about a portion of the wiring diagram
Have you looked at the internal Garmin setup menus for proper configurations ?
Help us Help you....

The answer to some your question is in the original post, maybe I didn't word it in such a way that is easy to understand so here it is again.

Is this a new problem that just occurred or new installation that never worked ? New problem, worked before when the plane was purchased
How about a block diagram ? I don't have that handy but will try to get it. Considering that it worked before, a block diagram might not shed much light.
Do the radios receive Ok ? Yes, very clear.
Affected on ALL frequencies or only particular frequencies. Multiple frequencies were tried and they were the same.
You say ATC says garbled or static - how about other aircraft in the air or on ground nearby ? Same, both air to air as well ATC has the same experience and tried it at higher altitude with no joy.
Antenna cables - check continuity and for shorts, Check antenna's. No, but the chance of both antenna go bad at the same time is very slim
Was an avionics shop involved or a home built setup - How about a portion of the wiring diagram. No
Have you looked at the internal Garmin setup menus for proper configurations ? I am not sure what configurations are available for radio transmission but sine it was working before, this seem unlikely.

 

[DerekS]

I am helping troubleshoot an issue with a friend and we discovered today that his radio transmission is completely unreadable. He has two radio, Garmin 650 and GRT200. We tried both radio from both pilot and copilot side and all is the same. We do see the TX on the radio so the PTT is working, plus ATC told us it is just static and unreadable. Both antennas are at the belly the standard location for the RV10.

Any thoughts as to what are the possible causes for a poor transmission? I believe it must be something that is common for both radio and the Audio panel (GMA 345) is the only thing common that I can think of. BTW, we hear others just fine without any issue.

Are you certain you haven't swapped co-pilot and pilot headsets... been there...

 

[Bavafa]

Are you certain you haven't swapped co-pilot and pilot headsets... been there...

I am not sure what that means or how swapping the pilot and co pilot headsets will cause this. But to be clear, a transmission call was tried from both side and both headsets with the same result.

 

[DerekS]

I am not sure what that means or how swapping the pilot and co pilot headsets will cause this. But to be clear, a transmission call was tried from both side and both headsets with the same result.

If you put the wrong headset on the wrong head. When you transmit it listens from the wrong mic and you are very quiet to unreadable.

Derek

 

[Bavafa]

If you put the wrong headset on the wrong head. When you transmit it listens from the wrong mic and you are very quiet to unreadable.

Derek

I see what you mean now, a good point and worth trying. Thank you for this suggestion.

 

[AZSteve053]

If you put the wrong headset on the wrong head. When you transmit it listens from the wrong mic and you are very quiet to unreadable.

Derek

With two people wearing headsets in the subject plane - can they communicate with each other using the intercom function ? This was asked before but I did not see a direct answer.
It's important to know this - if the intercom function is not working then then radio transmissions are unlikely even if PTT's causes a Tx indication. Also - make sure audio panel IS TURNED ON and not in the emergency backup mode.