APM 2.6 Radio Calibration Failure

[GlassKnees]

I'm repairing my Tarot FY680 Pro hexcopter - replaced the #4 motor, GPS mast and APM flight controller which I bought on Amazon. I've built three multicopters, all using clone APMs, so I'm pretty experienced in wiring, configuring and flying them.

I successfully downloaded the firmwware and performed the accel calibration; this morning, I successfully calibrated the compass and then tried the radio. I'm using Spektrum radios - DX7 transmitter and AR8000 receiver:

When I turn on the transmitter, the receiver lights up, so I know that it "sees" the transmitter, and I get the green bars with the red lines on the Mission Planner display. But when I move the sticks on the transmitter, there is no response in Mission Planner. I'm beginning to suspect that I have a bad APM, but before I send it back to Amazon, I thought I'd ask for help - maybe I've overlooked something obvious..

 

[GlassKnees]

Problem solved. After some troubleshooting this morning, I isolated the problem to the servo wires going from the receiver to the flight controller. Fortunately I had some new wires so I swapped all of them. I successfully completed the radio calibration. After I resecure the receiver, I will repeat the calibrations and hopefully do a test flight later today.

 

[GlassKnees]

Here is a picture of my Tarot Hexcopter with repairs completed and ready for a video test flight:

The two small lipo batteries strapped on the platform above the gimbal are for powering the gimbal and the video transmitter.

 

[GlassKnees]

Yesterday's test flight was a bust. When I took it out to the field and powered it up, the camera tilted downward and I could not tilt it at all. It was a windy morning but I took off anyway. The aircraft flew fine despite the wind and I recorded video, which wasn't very interesting. I let the autopilot land the aircraft as it does a better job under windy conditions than me - any lateral movement during landing will cause the skids to catch on the ground and risk tipping over, but the autopilot lands it just fine.

I discovered that the gimbal works okay when it is powered up by itself but tilts the camera down when I apply power to the aircraft. I downloaded the Feiyu-tech configuration S/W as well as the firmware installer, but the gimbal already has the latest firmware. After messing with the configurator a bit, I got the gimbal to work and tilt on command with the aircraft powered up. I'd like to take it out for a test flight this morning but the weather isn't cooperating - windy, cloudy and increasing chances of rain.

If you look closely at the camera, you'll see the light blue Tarot fitting around the lense for mounting it on the Tarot 2D gimbal - I'm down to a single camera and so I have to swap it between the two platforms (this one and my highly modified Elev-8). Here's a pic of my Elev-8: