Hello Steve:

I grabbed the SX-100 schematic and see that it uses tapped (but not center
tapped) transformers in the second and third stage. I suspect that these
are the same transformers, with the same taps. Hallicrafters probably used
the same transformers for the SX-96, the SX-100, and the SX-101. The S-76
was one of the first to use the 50 kHz (whoops kc) transformers. I know
there are a lot of parts units floating around so you might check the
manuals of those to see if they are the same.

It is late and bed time, but I have the SX-96, 100, 101, 88, 115 and 117 I
could check (no you cannot have the transformer out of my 88).

Although you could duplicate the coil, it should be fairly easy to find a
replacement. That way, you will not have to determine the tap and duplicate
the coupling.

73, Colin K7FM