I was once told that I had to only use a PCM receiver when using an electronic ignition on a gas engine. Is this true or can I use an FM receiver? To this point I have only run magneto ignitioned engines and have had no problem using FM receivers. I was told an electronic ignition interferes with the receiver. Any advice would be appreciated. Thanks!

I currently have 5 giant scale gasoline powered planes which I fly. Not a PCM receiver in the bunch and no ignition noise or glitching. All have electronic ignitions, CH Electronics and Falkon. Most have shielded ignition caps and one doesn't (Brison 6.4 twin). I run Futaba, Hitec, and FMA receivers, all with Futaba transmitters (2).

PCM will work fine but don't let anyone tell you that you must have PCM for gasoline engines. Good installation is the most important thing to prevent radio noise.

Ken

Greatest majority are on straight AM.

On what planet???? I'm sorry, but AM is pretty much as dead as the proverbial dodo bird! PPM is just fine, and while I have used AM in the past, I would suggest that if anyone still has an AM radio, they get into this century and upgrade it.

Jim

Sorry, meant FM . To much flying today. Pooped out.

Thanks guys, I'll stick with the FM receiver. How can you tell if an engine has a shielded spark plug cap?

Not all engines need shielded plug cap. None of the dozen engines I have do. Make sure you use a resister type plug in it though. Most Mfg. have an R in the plug # such as Champion RCJ7Y. Make sure you do a range check. It will be slightly less with the engine running.

Good, thread, but I have a sporatic glitching problem on my OMP 65" Yak that I could use some help with.

The plane range checks just fine on the ground with and without the engine running, only thing is we have to lift it a foot or two off the ground. The antenna runs out the bottom the the plane, so it is very close to the grass. We range checked it again on Friday at about 150'

The plane has a G26 on it with RCIGN ignition conversion.

Because of the size of the plane, the ignition battery is only inches away from the receiver. It is wrapped in aluminum foil.

The glitching is the same with either a Hitech or Futuba receiver.

I have a Fubuta PCM receiver that could go in the plane, but I would like to solve the problem first. Any suggestions?

Chuck

FM (PPM) gets a little too exciting for me, if the radio sees some interference. The servos go every which way. It's kind of hard to jump out of the path of the plane because you don't know where it's going. With PCM there's less excitement. With interference, the radio can be programmed so that the engine goes to idle and the rest of the servos go to neutral. The plane may crash, but it's in a straight line at relatively low speed. Think about this scenario: your plane with PPM coming in for a landing, wheels touch down and roll out, you turn the plane to taxi back towards you, someone turns on your channel, plane goes full throttle and headed in the direction of the pits.

If the engine has a rubber spark plug cap, it is not shielded. If it has a metal spark plug cap, it is shielded.

PPM will work but PCM will give you better protection. If you have a choice I would use the PCM.

Yes, I would use a PCM FM reciever on a gasser.
Likewise, I would use an PPM FM reciever on a gasser.

Hope this helps....

Hi,

PCM only hides the glitches and interference. If that makes you "feel safer", then use PCM.

Personally, I use only PPM on my fleet of research planes (ca. 25 planes and all gassers) and solve any interference problems. All receivers are not created equal. Some brands are more selective and more resistant to interference than others.

Elson

Elson has it exactly right, find the problem and fix it, then it won't matter what modulation you use.

Hello,

What is wrapped in Aluminum foil, the receiver or the ignition battery? Does this help reduce interference? Haven't heard about this and am curious.

Thanks,

Travis

PCM is in fact a better receiver because it does not depend on integrety of the frame in order to get the information through. Yes, you should make sure there is no interference generater on the airplane but then PCM will give you better protection in case something happens. It will also hide a problem- but then thats what it is supposed to do. Check it with a PPM receiver then use the PCM for all operations. I would think you if anybody would want the best protection you can get. Since PCM is now the same price as PPM I plan to switch all my receivers.

I use a PPM RX to do my initial range checks so I can see any problems..after I eliminate as much RF as possible I put a PCM in and fly..

I have looked the plane over pretty thoroughly and it range checks just fine...150' with and without the engine running. I just get a little hit may be once everyother time out flying. Any suggestions of what to look at, I would like to solve the problem before using the PCM receiver.

Travis
It is the battery that is wrapped in foil.

If it range checks OK I would think you probably have some other problem such as an antenna orientation problem or a reflection off a building or fence in your flying area. These things show up with a PPM receiver. A PCM receiver will ignor it.
I used to fly a pulse width symmetry system years ago. With that system any loss of a pulse was apparent as a glitch. You were almost guaranteed to get a glitch on take off or landing when the aircraft antenna was pointed at you

Well I put the PCM Rx in the plane and went to fly it, but found a problem with the wing that grounds it temporary. Anyway, I range checked it with the engine running, plane on the ground, and the receiver flat on its back on the ground, it range checked at 200'. Definitely better than with the PPM receiver. I will know more after flying it tomorrow.

Chuck

I have PCM's in my Gas birds,,