hmmmmm, I may have found the answer in the following forum: Here they say the resistor addition is not needed:
Can you confirm that?
One more for good reason to abandon the stock radio and go to Frsky......
http://9xforums.com/forum/viewtopic.php ... +fix#p4609Re: How to use er9X with/as a buddy box trainer
Postby ShowMaster » Sun Feb 26, 2012 5:24 pm
The "ppm" fix is only needed if the stock FlySky or Turnigy rf modules is used in the trainer TX. The original modules load the 9x PPM circuit too much to be able to drive two loads, the master and trainer. The load it always there if the modules are plugged in. The resistor raises the load impeadance so tne trainer module can stay in. Not needed if Frsky rf modules are used In the trainer TX.
If you've installed the HK Backlight and not done the jumper "fix" on the HK connector board, the circuit error will fource the TX to "not" put out a PPM signal no matter what you turn on in the 9X menu with or without the resistor 1K mod.
Question?
Do you have the HK backlight installed and is it unmodified?
SM