• The Biplane Forum is a large global active community of biplane builders, owners and pilots. From Pitts to Skybolts, to older barnstormers, all types are welcome. In addition to our active community, our content boasts exhaustive technical information which is often sought after for projects and maintenance. This information has accumulated over the 12+ years the forum has been in existence.

    The Biplane Forum is a private community. Subscriptions are only $49.99/year or $6.99/month to gain access to this great community and unmatched source of information not found anywhere else on the web. We are also a great resource for non biplane users, since many GA aircraft are built the same way (fabric and tube construction). Annual membership also comes with two BiplaneForum.com decals.



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

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

bipedream

Registered Users
*
Joined
Mar 9, 2013
Messages
448
Reaction score
129
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.
 
Last edited:

Latest posts

Back
Top