What radio frequency and modulation are you using? Also, what's the radio make? Hopefully it isn't AM and certaily not 27 MHz. Hopefully not an offbrand radio.

Check the ignition cable for chafed and broken shielding (the braided wire) especially where it enters the plug cap.

CH is still in business and they should be able to repair the CDI module if it needs repair. At minimum, you may want to send it in for them to at least look at it and see if something has changed.


EDIT...Good someone was thinking along the same vein as me. The radio doesn't seem to be the culprit in this case....