Radio shack sells the type B plug (yellow) for a couple $. You can just make up your own this way the cable can be 20 ft if you want. Ive been running mine this way for a couple weeks now. Keep in mind the 6 Volt batteries come in 2 sizes square with 2 springs for connection and rectangle with 2 threaded posts. I am running the square one . Its an old battery that was for 5 years and the level is 3/3. Unit will run on the ext battery first as with batteries in unit and R/C hook up my level shows 1/3 as soon a s I hook up the Ext unit beeps and shows 3/3 for power.