The Alpha input network was a three winding auto-transformer with the input at the two winding point - a 2.25:1 un-un. It was about 1.25" OD but unfortunately, I do not have specifications for the core material. 73, ... Joe, K4IK -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com