Sorry this will probably be a long explanation. My question(s) are about 3 different Hitec receivers. Only one of them works for both of my helicopters, Hawk III mechanics (for a Bell 222), and my Hawk Sport. The receiver that works for both helicopters is:
Hitec HPD-07RH, FM, Q-PCM, Channels 1-7, and BATT and DSC/BATT
The 2 I recently bought that do not work are:
Hitec RCD-3800, HFD-08RD, FM, Channels 1-6, and B/7
Hitec RCD-3200, HFD-08RD, FM, channels 1-7, and B/8

My radio is a Hitec Eclipse 7. All receivers & crystals are channel 47, 72 MHz.

Is it because the receiver that works is Q-PCM (which I just noticed writing these down, and don't know what that means), and the others aren't? If so what is Q-PCM?
Oh, here's the servo's & Gyros for both Helli's.
Hawk III mechanics:
Servos: Hitec HS 425BB
Gyro: PG2000 Piezo

Hawk Sport (bought used/ARF, to practice with):
JR DS811's, JR NES537, and Hitec HS-5625MG
Gyro: The "old faithful combo" Futaba GY401

When I bought both receivers I told them what radio I had. Bought one from a LHS (not really local, but nice people), and another on line. Anyway, the good news is that my original receiver works for both, so in the mean time I can start to practice on my Hawk Sport. I just don't want to have to transfer it back & forth, esp, the Hawk III is going to be a scale Bell 222. Plus I don't like the idea of the "strain" on the wires,,, in & out, in & out. Anyway, as always Any help would be greatly appreciated I was working on the pitch for my Hawk III mech's, but then got sucked into this problem. One of these days I'll get both solved, with all of your help, of course
Thanks,
Joe
PS Just got Ray's manual, and started to read that