Radio Stack
Build log for the Cessna 172SP radio stack — GMA 350 audio panel, COM/NAV heads, and GTX 345 transponder.
Overview
The radio stack in the 172SP G1000 sits in the lower centre of the instrument panel. It consists of the GMA 350 audio panel at the top, followed by the COM1/NAV1 and COM2/NAV2 heads, and the GTX 345 transponder at the bottom.
In a G1000-equipped aircraft the radio heads are largely redundant with the G1000's own COM/NAV tuning, but they are retained for their physical presence and the satisfying tactile feel of tuning a radio with a real knob.
Components
| Unit | Function |
|---|---|
| Garmin GMA 350 | Audio panel — intercom, marker beacon, speaker/headset routing |
| COM1/NAV1 | Primary comm and nav radio head |
| COM2/NAV2 | Secondary comm and nav radio head |
| GTX 345 | Mode S transponder with ADS-B |
Build Approach
Each radio unit is a 3D-printed replica housing with:
- LCD display (small I²C OLED or custom PCB)
- Concentric rotary encoders for frequency tuning (coarse/fine)
- Pushbutton for frequency flip-flop
- Arduino Nano or Pro Mini per unit
Frequency data is read from X-Plane datarefs via CockpitConnect and sent to the displays. Encoder inputs write back to the same datarefs through the CockpitConnect bridge.
Audio Panel
The GMA 350 replica has toggle switches for COM1/COM2/NAV1/NAV2 audio routing and a speaker button. These map to X-Plane audio routing datarefs.
Status
Planning — no physical work started yet.