[Amps] Schematic for non factory 77 Dx two tube conversion

Mike Keller w1bnc52 at gmail.com
Sat Aug 12 15:23:17 EDT 2017

I have an Alpha 77Dx s/n 2710 that was converted "in the field" by 
someone to a Two tube version.

Looking at the original 77 series manual, there are notations in the 
schematic for the changes necessary to add the second tube but a look 
under the RF deck of this amplifier shows a very different approach to 
the conversion such as a bifilar toroid instead of L2 and L12 and a 
string of 1n4007 diodes in the Post detector. Was there a factory 
revision that may not be in my manual or could it be that this was an 
aftermarket modification?




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