I bought an SAB RAW 500 second hand (without FBL) with MKS HV9767 cyclic servos and an MKS HV9780 tail servo. I now installed a Spirit GT and wired everything up as in the attached file. My receiver is an FrSky R-XSR that I flashed with F.port firmware. I have a Radiomaster TX16S II Max transmitter in which I created a blank model and only configured and bound the FrSky R-XSR receiver (FrSkyX2 mode, LBT(EU) protocol).
When I connect the battery (LiPo 6s 4000 mAh), the tail servo occasionally makes a slight noise (the cyclic servos only initialize and then remain quiet). Then when I turn on my transmitter, the tail servo starts jittering like crazy. When setting up the FBL via the wizard, I entered the correct frequency values ​​for the tail servo (760µs/560Hz) and the cyclic servos (1520µs/333Hz) and I chose FrSky F.Port as the protocol. Does anyone have an idea of what could be the issue? I hope the tail servo is not toast

Hello,
The switching on sequence is wrong, the remote control is always switched on first and only then the helicopter and not the other way around, this is a fundamental error in operation!

Regards

Yes, you're totally right, that's also how I did it apart from the first time when binding. So, indeed, when I connect the battery with my radio transmitter on and the RAW 500 model selected, the tail servo first makes some slight noises and then starts jittering

I came across this thread and I knew that only the green LED was lit on my FrSky R-XSR receiver when it is bound to my radio. So I realised I had accidentally put the receiver in CPPM mode during the binding process . FPort obviously needs SBUS mode so I've now put the receiver in SBUS mode (green and blue LED on when bound) and the jitter on my tail servo is gone, hourray !!!

Now I noticed that, from time to time, my radio loses telemetry as described here, so I might downgrade the F.port firmware on the receiver from 2.1.1 to 2.1.0 and see whether that solves that issue.

As indicated in my first post, the tail servo makes occasionally a crackling noise (a bit similar to a Geiger counter with low radiation levels). Is this normal or does it mean the servo is EOL ?