Comm Issues + Garmin GTR 200 vs. Flightline FL-760

[bipedream]

I'm having comm issues in my Skybolt that I've having a hard time trouble-shooting. I'm looking for advice and thoughts on a replacement radio.

Current equipment:

• Skybolt with canopy
• VAL 760 comm
• Sigtronics Sport 200S intercom
• Clarity Aloft headset (tried DC and other headsets and that doesn't seem to be the issue)
• Narco AT-50a transponder with encoder

Symptoms

• Ground checks are fine with engine off and at idle or taxing just after turning everything on and starting up
• I get a high-pitched tone when transponder is on, this is annoying but doesn't really affect audio quality, I hear more background noise when other electronics are turned on.
• After a few minutes of the radio being on I start to get some static when listening or transmitting (crackling so it sounds broken). There seems to be a time dependence.
• During flight the crackling/static (only when transmitting or receiving) becomes so bad that I'm unreadable and can barely hear other traffic.
• Passenger hears the same issue so I don't think it is the wiring between the intercom and jacks unless both jack sets have the same issue.
• If I shut down and come back in an hour the radio seems to work again but then gets bad after ~10-15 minutes
• This has been getting progressively worse and has gotten to the point that I've had to switch to my handheld on the last three flights.

Trouble-shooting attempted

• Replaced coax between tray and antenna
• Replaced tray antenna connector on the tray (snap ring was broken on original)
• Cleaned radio contacts and Molex connectors on the tray side
• Ensured all of the contacts in the molex tray connector are secure (3 connectors seemed loose, positive power wire was tarnished ~black)
• The airplane puts some oil on the belly where the comm antenna is located. I tried cleaning the antenna but the antenna works fine with my handheld.
• The handheld doesn't pick up any of the avionics noise, even when placed next to the current VAL and using the same antenna.
• I talked with a local avionics shop and they don't work on VAL's.

Any suggestions for next trouble-shooting steps?

Does anyone in the Seattle area have a known good VAL on a shelf that they may be willing to loan to see if I have bad contact within the radio itself or somewhere in the wiring? I'm suspicious it is the radio itself.

I'm considering just starting over with either the Garmin GTR200 or a Flightline FL-760 2 1/4" comm and getting a pre-made wiring harness from Aircraft Spruce. I like the weight and cost of the 760 and if I have to go up in price the Garmin looks like a nice radio. Either form factor works.

Has anyone tried the Garmin GTR 200 and used the internal intercom in a high-noise biplane? I assume the Flightline intercom wouldn't good enough and I'd need to use my current Sigtronics but would be happy to hear feedback.

 

[PittsDriver68]

 

[Neil]

 

[TFF1]

 

[Tomcat]

 

[bipedream]

 

[Lotahp1]

 

[Tomcat]

 

[bipedream]

 

[StinsonPilot]