All was going swimmingly until I thought I would try a short flight in the back garden just to record a log so I could see what voltage the Graupner VR was giving in flight, see this thread:
I didn’t connect the secondary power supply at all, she armed ok until I plugged in the telemetry sensor at which point the tx gave a low rx voltage and no signal warning, the rx led went out and the Pixhawk gave a series of tones. I disconnected everything, removed the telemetry sensor and connected the lipo again and this is what the Pixhawk now does:
It’s worth mentioning that the telemetry sensor plugs into the lipo balance plug (which wasn’t reversed).
It’s all a bit bizarre as I spent half an hour with everything plugged in last night when I was tuning a new 32bit Alexmos controller for my gimbal without incident so I guess that the culprit must be the sensor but how or why I don’t have a clue…