[Heathkit] HP-23 Mystery 6.3 volt Green Wire???

[OTAKEBI at aol.com]

Gary, It is the HP-23.
Not A,B,or C.
The transformer number on top is 54-807 549-7936.
When I got the supply the bottom of the case had an electrical burn right  
under the transformer but the supply checks out FB.
I think it might be that the guy I got it from changed out the transformer  
out of a B or C and those did not have provisions for 6.3 volts.
I guess that the transformers in those did not have a center tap from which  
to provide the 6.3 volts.
This is just a guess on my part.
Dan/N4VET