• 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).

Transponder wiring..


Well-Known Member
Lifetime Supporter
Aug 18, 2006
Reaction score
I wired up my transponder to the altitude encoder today. Involves crimping the molex connector at the back of my Narco AT50 transponder to the encoder, which came pre-wired.
I know the transponder is operational as I recently got it tagged.. but I have no way of testing it... not near any airfields out here. One thing.. when I turn it on, it emits a very high pitch tone.. like a squeak.. quite soft, but doesn't stop.
Honestly, I've never turned a transponder on without an engine running, so have no idea if this is normal... anyone know anything about the Narco ?
PS - pretty sure the wiring is good.. have both encoder and xpdr installation manuals, and it seemed basic enough.


Latest posts