So I've killed both of my 3DR branded telemetry radios after moving them to a new aircraft. They worked great for a couple of years in a DJI F450. I recently moved one to a new build, along with the DJI E300 power system. The flight controller, PDB, airframe, and video TX are new.
I moved one 3DR radio to the aircraft as the remote, and kept one as the local radio. The remote radio worked perfectly, right from the start but failed after a few minutes of operation. I took it apart and found a bunch of what appeared to be cold solder joints. I touched them up but that didn't restore operation. I put the other 3DR radio in the aircraft and bought a RFD900 for the ground station. The second radio worked perfectly for a short time and then failed.
Some differences between the old quad and the new are: carbon fiber airframe (TBS Discovery knock-off), video and telemetry antennae attached to bulkhead connectors instead of directly to the radios, CC3D flight controller instead of Pixhawk, and Matek PDB with integrated regulators instead of Pixhawk power supply and separate BEC for the 5V servo rail. The video TX is a Boscam TS5828, 600mW unit.
I've verified the telemetry pinout and supply voltage. The voltage is about 4.85V at the radio. I've looked at the possibility that having both 3DR radio and video TX antenna grounds connected through the bulkhead connectors and CF frame could be causing a short, like if one had a positive ground and one negative. However I would expect them to show a voltage difference when isolated and I'm unable to measure any voltage difference.
I'm stumped. Is there some compatibility issue that I should be aware of? I need to get telemetry working, but don't know if I can chance another radio failure. The first two were $100.
Thanks for any assistance!