Futaba R127DP Rx: PCM1024 *AND* PCM512?
I have two older Futaba PCM transmitters, and two old Futaba R127DP receivers. One Tx is a PCM1024 type, the other is a PCM512 type. (PCM512 was an early version of PCM, that was phased out when PCM1024 became the standard that mosts PCM systems use today. PCM512 and PCM1024 are not compatible with each other, and only a few PCM512 systems were made).
I have seen Futaba literature that says the R127DP receiver is the only one that will work with both 512 and 1024. (There is an R128DP receiver that is PCM512 only, I don't have one). Most newer Futaba PCM receivers are PCM1024 only.
Both my R127DP receivers work correctly with my PCM1024 transmitter. They power up, move their servos as expected, etc. Neither works with the PCM512 transmitter, the servos stay dead. (The two transmitters are on Ch52 and Ch56, I swap crystals in the receivers appropriately). Maybe something is wrong with the PCM512 transmitter, I suppose. But it gets a good power indication on its meter, the lights flash just the way the Tx manual says they should when I power up, and I put an oscilloscope on the antenna and found a 72.830 MHz wave (correct for Ch52), amplitude around 20V p-p, which sounds pretty hefty to me. I'd like to think the 512 Tx is working correctly.
My question is, Does the R127DP receiver really decode both PCM versions? Can it switch automatically from one to the other, depending on what it hears? Or do you have to open the receiver case and flip a switch or change a jumper somewhere? Or does Futaba literature mean that SOME R127DPs were made for PCM512, while other R127DPs were made for PCM1024, and you still can't use one for the other?
Any advice gladly accepted!