found the glitching issue, need help solving it

[kufman]

FM and AM are in the same carrier band, both are susceptable (sp?) to mechanical vibrations. This is supposed to be the advantage of the newer 2.4GHz systems.

As for the problem. does you antenna wire run under the chassis and then up through the antenna mount? Is the receiver padded from the aluminum chassis? I am with the guy above who suggested trying a regular receiver pack once to see what happens. be sure to remove power from the Ubec when you do this experiment.

[BrianG]

Originally Posted by kufman

FM and AM are in the same carrier band, both are susceptable (sp?) to mechanical vibrations. This is supposed to be the advantage of the newer 2.4GHz systems.

That is true, but AM has the actual signal modulated on the top of the carrier frequency, which is the worst place to be noise-wise. FM shifts the carrier frequency by the signal amount. Also, FM [should] chops the top and bottom on the carrier wave. These together help eliminate a lot of RF noise. But if the noise (or harmonics) is close enough to the radio frequency and is powerful enough, FM still suffers. But AM is worse to be sure. Granted, I am assuming AM and FM radios work like regular radios (the music kind).

Aside from the 2.4GHz systems being at such a high frequency, the radio and receiver employ error correcting in the digital packet transfer (at least in the ones I am familiar with). Both of these together make for a very reliable link.

[ncalenda]

I did a test yesterday, and moved the BEC away from the receiver, and behind the tranny. The glitching was the same, and if I lowered the radio, it made it worse, and the distance was only like 30 ft.

When it was near me, no problems at all!

Here is my plan, since I have the Futaba 3PM-FM I feel I have to stick with FM, I really don't want to pay for the switch to 2.4 GHz.

So, I'm thinking of getting a new receiver and digital servo:
Futaba R203HF 3-Channel FM 75MHz Rx
Hitec HSC-5955 (I'm assuming this servo will work fine with this setup)

Do you think this will solve the problem? My BMS-660MG has metal gears, and a heat sink, which may be causing the interference.

Plus, isn't digital servos better?

If I can do this to solve this problem, then I would be happy. I do believe the 2.4GHz system would fix this problem but I'm not sure I need to go to that at this point.

[kufman]

did you try using a regular receiver pack?? or moving the antenna and receiver off of the metal chassis? These are free things to try before replacing parts that may not be the problem.

[ncalenda]

Originally Posted by kufman

did you try using a regular receiver pack?? or moving the antenna and receiver off of the metal chassis? These are free things to try before replacing parts that may not be the problem.

No, but I should. How would you move it off the chassis, just put it on plastic?

[ncalenda]

BTW, I had this problem with the plastic chassis, with this new setup (I rebuilt the entire truck last weekend) I moved the ESC far way from the receiver. I should still test it without the BEC and maybe move it away from the servo to see if that helps.

[kufman]

May not help if you saw it with the plastic chassis. You can still try it though. Mount it on some foam padding or something that can absorb mechanical vibrations. Also, try to route the antenna wire so that is does not pass through the metal chassis. You can always make a small hole in the side of the antenna tube and get the wire in that way. Be sure to keep the receiver and antenna wire aways from battery and motor wiring. Your antenna is very close to you battery pack. Just for kicks, you could temporarily more the antenna tube to the shock tower and stin the receiver around so that the wire end of the receiver points toward the shock tower. If you are carefull you could also move the receiver to the shock tower as well to keep it away from everything.

I would still suggest trying the regular battery type receiver pack once just to see. It will help rule out the possibilities.

Be careful when moving to a HiTec digital servo. I have seen them fail in very strange ways. My friend had one die at a national level sedan race. He would just randomly get severe gitters and then it would go away. It turned out to be his HiTec digital servo!

Keep us informed.

[ncalenda]

Originally Posted by kufman

Be careful when moving to a HiTec digital servo. I have seen them fail in very strange ways. My friend had one die at a national level sedan race. He would just randomly get severe gitters and then it would go away. It turned out to be his HiTec digital servo!

Which servo would you recommend, if I end up doing that?

I will move the antenna and receiver to see if that helps, good ideas!! I can also slide the battery pack back some, which I will do too, as well test with a receiver batt pack.

Thanks again, I will keep you posted, it would be good to figure this out.

Try install a toroidal core on your ESC's receiver wire. If that's too much effort, try one of these.

Oh, and ensure your crystals are properly seated!

After some deeper thought, before spending money do that range check with your receiver removed from the model, and only one servo and power plugged into it. If you get the same glitching your receiver's and/or transmitter's center frequency has probably drifted and you need to:

* Get (a) new crystal(s).
AND/OR
* Send it/them in to be recalibrated.

If you are going to get a new radio, perhaps you should consider something other than FM. When we first put my buddy's 8ight together, he opted for a JR XS3 (I think) FM modulated system. I don't know what it was because we could never get rid of the glitching. He went and traded it in on a Spektrum system and all troubles went away.

Just some food for thought.

[BrianG]

All I know is that I have NEVER had any glitching problems with the Spektrum. As a result, everything I own is Spektrum. As soon as that new 30-model-memory comes out, I'll pick that up and sell my DX3 and DX3.0 transmitters and rebind the receivers to the new one...