Roger,
Läs här och kolla om det kan vara samma orsak på din radio till att säkringen gick som näms där:

http://www.rcgroups.com/forums/showthread.php?t=1372434

there is a Wire located at the GIMBAL of the Potentiometer, The wire is NOT PROPERLY ROUTED, the GIMBAL Move Back and Fort, the wire is constantly touching the SHARP EDGES of the VOLTAGE REGULATOR........if prolong use, the wire will eventually striped its insulation and might cause short circuit.
you can re-route the wiring to avoid it from touching the regulator........of you can cover the regulator with a mylar plastic insulation.