Ok, so here's the story. I had a trainer that is no longer with me anymore after a pretty bad accident. Let it be known, I was not the one flying! The engine and radio equipment all survived, so no problem there. I'm building a J3 Cub right now... and I bought all new servos and an engine for it because I started building it when I still had the trainer. I'm not very experienced when it comes to this stuff... so I'm just going to tell you what I have, what the problem is, and hopefully get some helpful answers! For the Cub, I bought a Tower Hobbies System 3000 receiver, and Tower Hobbies System 3000 servos. My controller is pretty old... I think we got it back in '94.. '95, around that time. It is a Futaba.. PCM 1024. The receiver I was using in the trainer was a Futbaba PCM 1024. The sticker on the back of the controller and BOTH the receives has a big 36 and then 72.510 MHz. I figured since the frequency is the same, I could use the same controller for everything I have.

Well, here's the problem. My older receiver that I used works with the original Futaba FP-S148 servos that were in the trainer... but doesn't work with the Futaba S3003 or the Tower Hobbies System 3000 servos. The Tower Hobbies System 3000 receiver doesn't work with any of the servos: Futaba FP-S148, Futaba S3003, or even the Tower Hobbies 3000. My controller has a "Trainer" switch on the very top right and when plugged in with a setup that doesn't work, if I flip that switch, the servos sometime twitches.

I realize that a lot of this might be a little hard to understand, since I just basically typed gibberish in my opinion... but hopefully someone out there might be able to help. Is it a manufacturer issue? Can I not use a Futaba controller with a Tower Hobbies receiver and servos even if the frequency is the same? That's the only thing I'm able to think of. I included a picture of my controller, just in case that might help! Thanks!

The problem is with the transmitter/receiver.

The transmitter is a PCM transmitter (this has a "fail safe" mode ) and REQUIRES a pcm receiver.

The receiver is a regular fm receiver. It will work with NON PCM transmitters.

You will need to either change the transmitter for a non pcm transmitter OR change the receiver for a pcm receiver.

My suggestion would be to sell the transmitter on RC Universe or Ebay and get a regular fm transmitter. The 2 big "selling points" of PCM are the fail safe and they are SUPPOSED to be more resistant to outside interference ("hits/glitches" ).

I have been flying for several years now and have had 2 "hits" in that time - one for about 2 seconds and the other did total my plane (some kids a mile away using the aircraft band ON MY CHANNEL NO LESS, for RC cars ). Other people who fly at my field have not been bothered by hits.

Unless people at your field have been bothered by a lot of interference (hits), I would not spend the extra money for PCM.

Campy is right. Also, it is my understanding that PCM has been an ever-evolving thing. Therefore, the PCM protocol used in the mid-90's by futaba might be different from the one used today. Therefore, you might not even be able to find a rx for that tx. Sell it, or give it away, and get you a good, new tx that will do both (most now a-days will do both, PPM and PCM).

What about the new servos with the old PCM receiver? Should they be working if I have the PCM controller and receiver?

well... i have to disagree to some extent. one time i was flying my piper cub and after take off it started to go haywire. i would have intermittent control but luckily while i wasn't controlling it, it came back to failsafe and through this intermittent control i was able to fly her around for an emergency landing. by the time i was turning in for final, i had made my way all the way from where i was flying on the left of the pits to the the beginning of the runway to ensure i had the best reception possible. i landed without incident.

i immediately stormed to the frequency board to see what had happened. as far as i know i was the first to sign in on that frequency and no one had called me on my mobile phone or alerted me otherwise. as i looked at the listing, i found that someone had put the same frequency as i did and didn't call me to let me know he was going to fly. angrily, i called him. he answered and i was about to go off on him when i heard his heated voice (he thought I had shot HIM down) in both ears and looked to see him carrying his engine in one hand, fuel tank dangling, and some plane parts in the other. i felt bad even though it was his fault. i showed him clearly that i was first to register and he should've informed me. he had just missed my band.

had it not been for PCM and failsafe, my plane would've been just like his. i believe that it was the better radio and the PCM that saved my plane from emminent death.

that being said, i fly most of my planes on PPM and only fly my cub in PCM since i have the rx from the original set. PCM rx and much more costly than generic PPM but you will not have the same level of safety.

funny thing about that day was that i he was actually teaching a student then and i heard from people around him at the time that he was yelling at the student for making all these strange movements and then crashing his plane. i hope he told the student the truth... otherwise he may never have the galls to fly again!

As long as the receiver can "Hear" the transmitter, the servos should work. The problem is the PPM receiver (regular FM receiver ) can not "hear" the PCM transmitter - it is like the transmitter and receiver are on different channels.

You may check with Futaba Support for a better answer. I am not familiar with your specific transmitter, however over the years with all the other transmitters that I have, they are "PCM/PPM".
The transmitter will transmit in either. You have to select. Generally there is a mode-select switch -- like a servo-direction switch -- on non computer transmitters.
The PPM mode will work all your other same channel, non-PCM, negative-phase receivers. The receiver operates the servos.

Should be able to get adapter cables for the servos.

Others have answered the PPM/PCM question (your PCM transmitter will NOT operate a PPM receiver), but
the type of servo shouldn't matter. Neither type of servo will work with your new receiver because the receiver won't read the transmitter.

As to why the 3003 or 3000's won't work with your old receiver? Can't help you there. What you described shouldn't be happening.
Dennis-

As DBCherry said, the servos couldn't care less what receiver or mode is being used by the transmitter and receiver. All they want is a 1.5 Millisecond (+_0.5 milliseconds) pulse every 15 to 40 milliseconds on the signal line in order to work as desired. That is what the receiver of a working unit sends to the servos no matter the brand or whether digital or analog.