Saturday May 24, 2025
Backup Battery Wiring, GTX 45R Wiring (Electrical)
5.0 Hours

This morning, I wired up the backup battery system that provides backup power for the GDU 460 PFD, GSU 25 ADAHRS, GMA 11 magnetometer, and the GTR 205x radio. The other advantage of the battery is that it will protect those components from brownout during engine start.

I made the transponder antenna coax. The instructions have you make it at least 3 feet long to avoid interference problems.

Then, I made the main transponder connector. This includes power, ground, and RS-232 connections to the ADAHRS and GDU screens. There is one additional connector to make that includes the HSDB connection to the GTN.

Then I played around with the system for awhile. I tried to see if I could change the 'NAV 1' designation to be 'NAV 2', since the nav radio is on the GTN, which I have designated as COM 2. However, the G3X system would not talk to it if I designated it 'NAV 2'.

I wanted to see if I could get any traffic hits from commercial flights overhead, but it seems there's too much interference in the garage.

Wiring I still need to do: Most of the GEA 24 engine monitor inputs, GTN -> GTX connection, CO monitor, ELT, seat heaters, roll trim, install the pitot heat regulator, static pressure lines, and install/wire stick grip switches. Things that have to wait for the canopy to be installed permanently: cooling fans, LED lighting, and G3X GPS antennas. Things that have to wait until the wings and tail are installed: GSA 28 roll autopilot, temperature probe, landing/taxi lights, nav/strobe lights, pitch trim, NAV antenna, and pitot heat/regulator.

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