RE: Changing Crystal On TX
The problem arise from those companies that PAY to use the channels in between the channels assigned to modellers. If they start getting interference from you and your transmitter, you can guarantee that they will complain to the FCC. As they are paying customers, don't you think somebody would start looking at the cause ??
Remember that they are only 10KHz away from you, if your original crystal is off frequency (as they can be quite easily), the deviation adjustments will bring it back on frequency. You then change the crystal for one that happens to be spot on freq, no unless the deviation is readjusted, those initial offset adjustments (for the old crystal) can easily cause you to be off frequency and splattering into adjacent channels.