I have a working transponder an Encoder for sale I bought a few months back
and won't be using. It has been checked out by an avionics shop, works fine.
Includes Transponder, ACK A30 Encoder, tray with all wiring and connectors.
Plus a wiring schematic I downloaded for the encoder.
$679.30
See my other listings on www.Barnstormers.com under "Rocca Aircraft Sales"