RE: XP8103....Help!
Having the correct modulation is very important. If you have a Non-PCM Rx or you are using your Tx with a Flight Simulator, you need PPM Modulation. If you are using a PCM Rx, then you need to set the Modulation, on that Model Memory, to the correct version of PCM. When you have the correct Modulation and the correct channel. you should be communicating. This is true for Hitec, Futaba, Airtronics, etc.
If you buy a 2.4 module, you also need to set the modulation to PPM.
If you switch to a dedicated 2.4 Tx, you won't have to worry about modulation.