I have a Homelite 25cc conversion in a 100" WS H9 J3 Cub. This is my FIRST gas engine of any type, so I realize this is probably another dumb question. Please be gentle! [sm=red_smile.gif]

This engine and plane ran and flew very well, but didn't have a kill switch that I could activate with my transmitter. The president of the club where I fly strongly suggested that I install a kill switch that I can activate with the Tx.

OK, no problem, I think I can do that. I bought a 250V 6A micro switch from Radio Shack, and wired it into the existing kill switch on the side of the fuse. I confirmed that all that original kill switch did was connect to ground to kill the engine, so I wired my micro switch in parallel. I made up a little piece of lite ply to hold the HS-81 servo close to the micro switch, and mounted it as far away from my Rx as I could. (Picture below) Now, when I flip my gear switch on my Tx, the servo trips the micro switch and kills the motor. And, my little homemade remote kill system does work just fine to kill the motor!

However, ....here's the problem. During testing, my engine started to blip and lose RPM's momentarily. It would nearly die sometimes. I checked my newly installed remote kill system, and sure enough, the servo is twitching and gyrating like all get out. During the servo twitching, it nearly shuts the engine off sometimes, and the sequence coincides with the engine blips. Obviously, it is NOT going up like this!

So, I assume it is interference from the magneto that is affecting my servo. (Right or wrong?)

How can I stop the interference? I thought that I should keep the remote kill system as far away from the Rx as I could, so I mounted it as far forward as possible. What do you recommend?

Thanks in advance! ...Ken

Oh, I forgot to add this. Just to be CERTAIN it was the servo twitching causing my engine blips, I unplugged the kill servo. Problem gone!

So, I still need to figure out how to get the glitching to stop.

Thanks in advance! ...Ken

http://www.rcuniverse.com/forum/m_60...tm.htm#6036766

I don't think any of the problems described in the link applies here. The ONLY servo that is twitching is the remote kill servo. All the other servos operate normally. The remote kill servo is the closest one to the engine, so that is what I am suspecting as the cause.

Kill wires can cause interference. I would run a setup with a plastic pushrod from a rearward mounted servo to a kill switch, and keep the kill switch near the engine with short wires. Another way some people run a radio operated kill setup is with a plastic pushrod setup to the choke.

Also, a friend of mine had a problem with radio interference on a Homey 25cc with the original magneto. We shielded the plug wire and kill switch wires and the glitching went away. For the plug wire we used the shielding off of a piece of T.V. coax cable. For the kill switch wires I had some aircraft shielded wire. Radio Shack might carry it....

Note: Any shielding used gets grounded on only one end.

AV8TOR

Thanks for the advice! For the time being, I have removed my remote kill system. It was so simple and neat.....

Oh well! Back to the drawing board!

Yup... what av8tor1977 said. Keep those wires away from the servos.

Personally what I do is to take the stop screw out of the carb, and just set it up where the trim kills the engine. Then I mount an outside switch to the kill wires for an non-radio engine stop.

Or, you can just move up to 2.4ghz.

You could perhaps hang on to your nice servo/switch setup to turn on an electric smoke pump....

AV8TOR

I agree with Av8tor1977 and Dr Honda, regarding the safe positioning of items relative to the ingnition components...and the use of the throttle trim to kill the engine, along with the stock grounding switch. If you want a similar setup to what you have, for redundancy, use a standard size servo, and operate the choke on the engine. Flip your gear switch to choke your engine. This is cool for starting it up, and if needed, you flip that switch on a warm engine and your engine stops, immediately.

Chad

OK, here's an update on my kill switch.

Firstly, I don't have a choke on my engine, so activating it isn't a possibility. Secondly, I can't kill this engine by closing the throttle. It just wants to run forever. It got down to 800 RPM's and STILL kept running!

So, I went back to my kill switch idea. I mounted the micro switch 8" away from the servo, and as far away from the Rx as I could get it. I used a Sullivan plastic control rod to activate the switch, and made some braces from light ply to hold the plastic rod in place.

Success! The kill switch works just like I wanted it to, and this time with no glitching! Thought someone else might benefit from my original mistake. If you are going to set up something like this, you HAVE to keep the servo separated from the wiring. I imagine the farther away, the better!