My equipment:
- Turnigy 9XR Pro Transmitter
- OrangeRX 1W 433MHz TX - https://hobbyking.com/en_us/orangerx-op ... tible.html
- Flytron RX v2 100mW RX - http://www.flytron.com/openlrs/146-open ... er-v2.html
- APM 2.6
Firmware:
- OpenLRSng OrangeRX TX v3.8.8 for TX
- OpenLRSng Flytron RX v3.8.8 for RX
- APM v3.4.0 for APM
The problem:
When I power up the transmitter as I'm standing next to my plane, it works fine. I can move all of the control surfaces and it works great. As soon as the plane starts flying out -- at around 20m -- I lose RC comms with the plane and it crashes to the ground.
Here's a video from this morning:
https://youtu.be/vWRnioX5gwE
You'll notice that I lose comms at about 0:08 in the video, when the transmitter starts beeping.
Here's what I've tried so far:
I suspected an issue with the stock antennas, so I did 2 trials using different combinations of antennas:
Trial #1:
TX: 433Mhz sander antenna
RX: 433Mhz stock HobbyKing antenna
Resulting range of 13 meters before the transmitter lost the signal (!)
Trial #2:
TX: 433Mhz stock HK antenna
RX: 433Mhz stock HK antenna
Resulting range of 7 meters

I then switched location, in case there was some sort of interference at 433Mhz:
Trial #3 (at a different location):
TX: 433Mhz HK
RX: 433Mhz HK
Resulting range of 7 meters
I then used a different transmitter/receiver, that uses 2.4Ghz instead:
Trial #4:
TX: 2.4Ghz HobbyKing
RX: 2.4GHz HobbyKing
Distance of several hundred meters (this is a different transmitter, and a different receiver -- works great!)
Ok, back to the 433Mhz system again .. now using the original antenna that came with the OpenLRS receiver:
Trial #5:
TX: 433Mhz HK
RX: 433Mhz OEM antenna
Distance of 16 meters
Oh c**p .. ok, let's see -- I'm using PPM, let me try doing PWM instead (maybe it's some sort of PPM configuration issue):
Trial #6:
TX: 433Mhz HK
RX: 433Mhz HK with PWM instead of CPPM
Distance of 5 meters

Ok, this must be some sort of hardware fault. Let me replace the RX module with a new module of the same type:
Trial #7:
TX: 433Mhz HK
RX: 433Mhz HK with different RX module
Distance of 3 meters
Aha, must be the TX then .. let's replace that with a new module of the same kind (OrangeRX TX):
Final Trial #8:
TX: Different 433MHz TX module
RX: 433Mhz HK stock antenna
Distance of 20 meters
Oh dear, I really have no idea what could possibly be wrong at this stage!
Every time I swapped out modules, I would flash the OpenLRSng firmware again (the latest 3.8.8 release) using the Chrome OpenLRSng configurator.
At this point, I'm completely lost as to what to do next. What could possibly be wrong here?