ScottMcM

My Feedback: (66)

I've got a Futaba FP-R138DP dual conversion receiver that is acting strangely. When it (and the radio) is turned on, it pulses...in other words the servos move, in a pulsing manner. If I advance the throttle, it stops, but it begins again if I move any other control. My radio is set correctly to PCM, and the battery is fully charged. I switched it out for a PPM receiver, set my radio to PPM, and the replacement works perfectly. Obviously, I'm not going to use the receiver, but I'm curious as to what may be causing this. Any ideas?

Charlie P.

Are you using it indoors (like under a fluorescent light or near a battery charger or electric motor) or is the Tx within a few feet of the Rx?

ScottMcM

My Feedback: (66)

I first noticed it at the field while I was doing a pre-flight on the plane. Originally, at the field, it would stop when I advanced the throttle, and not start back. Now, at my shop, it starts back as soon as I move any control. (This is happening inside, but there were no flourescent lights or chargers on at the time.) I haven't tried it again at the field. The transmitter is close, but no closer than it is to any of my other PCM receivers, and none of them have this problem.

BarracudaHockey

My Feedback: (11)

Sounds like a problem with that reciever. Send it in, its got something bad or going bad.

ScottMcM

My Feedback: (66)

Yep, I may as well send it in. Definitely don't want to use it as it is. Thanks for the help, guys.

Charlie P.

It is a weird one. I had an old ferrite car battery charger that would cause nearby receivers/servos to twitch about every three seconds. Didn't take long to figure that one out; it hummed loud enough to hear clear across the cellar.

ScottMcM

My Feedback: (66)

This twitch is about every half second or so, in a definite rythm. I also noticed that there is a half second to a full second delay from the time I move the stick, to the time the servo moves....and then it twitches back and forth. When I move the throttle, the twitching stops....until I move any other stick....then it starts twitching again. It has a definite rythm, which made me wonder if it was being caused by some outside source. Thing is, it is the only one of quite a few PCM receivers that does it, and it does it anywhere, inside or out. (I hooked it back up today, and took it outside. I also moved away with the transmitter...made no difference.) It kind of reminds me of an RC plane I saw as a child....if my memory is correct, the guy called it the "galloping ghost". I remember the rudder twitching, much like mine is doing now....

Charlie P.

The old reed systems and escapements. Before my time, but not much. ;-) We have a few guys locally who still fly the old stuff from the 50's (updates as needed - kind of old fart steam punk)

Are you wearing a cell phone or Blue-tooth when you do this? They mess with some metal-detectors nowadays.

I'm not up on electronics (I learned tubes in Technical Electronics Pre-College Engineering) but there is nothing in a modern Tx or Rx that operates at a clock speed or cycle we humans can detect. You've got a real puzzler.

ScottMcM

My Feedback: (66)

Yep, my cell phone was in my pocket...hadn't thought of that. On the other hand, my cell is always in my pocket, and this is the first problem I've had. I think I'll send it in...

JoeAirPort

My Feedback: (41)

I have some of those if you want a replacement.

Pilotsmoe

How many cells is your battery? Sometimes the servos twitch a little with the 6v batteries right off of the charger

Pilotsmoe

How many cells is your battery? Sometimes the servos twitch a little with the 6v batteries right off of the charger