Just a suggestion:

Get 4 good Nimh rechageable AA batteries and a good charger. Keep one
pair in the charger and other in the MRX. Switch after every flight -
or day, if several short flights.

Advantages: No radio noise, no extra wires, can use your MRX in other
gliders/towplanes.

Disadvantages: If you do a long out and back, may need to have some
backup AAs in your landout kit. Have to remember to charge and switch
batteries.

Works for me - the rechargeable batteries last long enough for a long
XC, and I like having my MRX in all the club gliders and towplanes I
often fly in.

Kirk
LS6 "66"