All
Airtronics sets will probably not work with the parallel connector as the signal magnitude is too small. The serial interfaces should be fine. Alternatively a single transistor parallel interface should be OK.
I have just had the opportunity to get a Sanwa/Airtronics RD6000 transmitter connected to my 'scope. My PIC Serial interface works fine in both ppm and inverse ppm mode (no difference/re-calibration needed).
The RD6000 signal in normal ppm mode is 3v magnitude, based on ground with positive going pulses. In inverse mode the peaks of the pulses go to ground and the base level is at 3v. On this basis I cannot see why we have been having any problems with Airtronics sets. Both my circuit and the serial circuit in the manual should work fine. The magnitude might not however be enough for the parallel interface.
I would still love to get hold of a trace for the VG6DR analogue set as this is the only transmitter I have failed to get work in over 200 interfaces supplied.
Mike