I've heard pilot lamps last longer when run on AC but I'm not sure why. BTW the reason the ART-13, T-195, etc filaments were run on DC is that they are aircraft/mobile rigs where the primary power is DC. 73, Roger -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com