This may be a well known topic, but not to me! What happens when you operate a USA 60~ hi power amp on 50~? Does the filament voltage change? B+ voltage changes? any info would be helpful? thanks again alex w2ox/v47kp -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com