Transponder Installation

Don Zank: Hit your back button now if you haven't taken your blood pressure medication.

The antenna is mounted on an aluminum sheet spanning the longerons with 1/2" crosstubes at the edges. 'A' is the coax connection to the antenna.

Same view from the outside. 'A' is for antenna.

Back of the panel. The transponder is at 'A'. I fabricated a frame of aluminum angle to which the transponder's mounting tray is riveted. The hardest part of the installation was making the cut-out in the panel without machine tools. Careful sawing and filing eventually made a decently close fit. The shop I bought the unit from made up the wiring harness with connections to the altitude encoder, antenna, and power supply - well worth the nominal charge; made the installation plug and play, assuming it works. Stay tuned.

'A' is the blind altitude encoder; it's hung the inside of the nosecone with lord mounts. You don't need an expensive encoding altimeter to provide altitude information to the transponder; this little black box (which really is black, as you can see) does the same job for a fraction of the price. 'B' is the static line from the encoder with a quick disconnect to the static line to the panel instruments. I ran my static line up the front downtube and out into the leading edge tube of the wing. I could not imagine anywhere in the open fuselage that wouldn't be subject to pressure variations and the conventional port location on the side of the fuselage is subject errors in a slip. Someone on the list suggested this location. Made sense to me; thanks to whoever that was for the idea.

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