How to fix Jello in the Diatone 2019 GT R239, R249, R249+ and R349 plus final PIDs

The Diatone GT R249+ is my favourite traditional 2.5 inch micro quad based on it's relatively lightweight in this class, motors which have a wonderful mix of power and efficiency, reliable electronics and excellent built quality. My review of this quad is here and it is still available across multiple retailers.

However over a short period of time I started getting a lot of Jello which is concerning given the camera is a CCD which should be much more stable. I did a lot of PID and filter tuning but gave up after a while and let it sit on my shelf. Now I've come back to it with a fresh set of ideas and believe I have fixed the Jello problem once and for all. Firstly I can categorically state that in my case it was not the tune nor the propellers that fixed the issue as I've seen stated elsewhere. The issue is around the camera/VTX and this fix should be relevant to all canopy versions of this quad that doesn't use the TBS vtx i.e.​

GT R239 (2 inch plastic frame)

​GT R249 (2 inch carbon frame)

GT R249+ (2.5" carbon frame)

GT R349 (3 inch carbon frame)

What is the problem?
The problem is the way that the runcam TX200u vtx attaches to the camera. Although this is actually a very good clean vtx that is light and great for saving spaces it requires the manufactur to remove the screws that hold the camera lens housing to the sensor board and re-use these mount point to use longer collared screws that perform the same function as well as holding the vtx to the camera. What I think it happening is that this is compromising the solidity of the mount between the sensor and the lens housing thereby introducing vibration between these two units.

​Runcam tx200u  vtx

The screws that hold the vtx to the cam also hold the sensor board to the lens housing and I believe the connection between the board and housing is compromised as a result. At least the Caddx Turbo F2 has some foam tape between board and housing unlike the stock runcam swift although I don't believe a camera change is necessary.

How do I fix it?
As an aside you may have noticed I went down the path of changing the camera to a Caddx Turbo F2 (CMOS) cam I had lying around. You don't need to change the cam but the fact that mine is working well now with a CMOS cam (that is more susceptible to jello) is a great sign.

The first way to fix this is to remove the camera and vtx and carefully re-tighten the screws holding the camera sensor board to the lens housing. This may be enough. In addition you can glue the housing to the sensory baord using a self leveling glue like e6000 (my boring review here) or even hot glue taking care not to get it on the sensor itself - I didn't need to go this far on mine.

The other way to fix it that directly adresses the mounting issue it to separate the camera from the vtx, replace the screws that hold the lens housing to the sensor boards with the original ones and put it all back together. That way the screws that hold the camera to the canopy only need to support the camera (and not the VTX) and there should be less demand on the screws that hold the board to the lens housing. There is enough room at the top of the stack and enough slack in the wires to move the vtx on top of the plastic cover on the stack. This would be my ideal fix as it also offers more movement in camera angle - presently the vtx board prohibits full movement.

So there it is, better late than never so hopefully it helps some of you with the jello issue on an otherwise excellent quad. The good news is that all the work I did on the pids meant that it flies really nicely! If you need these pids please see below or more detail in my original review.

Here are my final PIDs for 3s - really pleased with these

Ready to go! I'd recommend running your vtx antenna like this - it's cheap and gets much better reception plus it keeps it well out of the props.

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