[Hallicrafters] SX28 power transformer.

[Mike Everette]

Brian,

That surely does sound like a non-SX28 transformer.  I have never heard on a 26 volt tap and 12.6 volt CT winding in a 28; there just isn't a use for them.

You could try checking the primary a little further.  If it is a dual voltage type, there will be 2 windings; they are in series for 230 and I think parallel for 115.  I don't have a 28 manual which actually shows a dual primary type transformer; but the US Navy RBK series (S-36 variant) has a dial primary and the windings are in parallel for 115 volts.

The best replacement, assuming an actual 28 transformer can't be found, might be an old TV power transformer.  They have enough current in the HV winding to handle the job, assuming you can find one with a secondary of 560-600 volts center-tapped.  Some US-made TVs by General Electric had transformers in that range, but they would be 115 volt primary.

As for Halli transformers, the one from the S-27 or S-36 is close except the high voltage secondary has a somewhat lighter current rating than the 28.  Since military spec transformers are often underrated by as much as 50%, a power tranny from a late-marque RBK (-12 to -16) might possibly work and "hold up."  Some of them were dual primary too.

73

Mike
W4DSE