Hello: I am offering a battery adapter for the PRT-4 transmitter that uses 2 each 9 Volt batteries. You can see it at: http://www.pacificsites.com/~brooke/4BA.shtml or as item # 1080138661 Note that I am using Dutch auctions with a reasonable high quantity so that you pay just the start price. 73, Brooke Clarke Products designed & built by N6GCE http://www.prc68.com