[Hallicrafters] SX28 power transformer.

[Mike Everette]

Brian,

What do your filament voltages look like?

The SX-28 power transformer is 580 volts full secondary, at something like 200 milliamps.  This should give, of course, about 290 volts or thereabouts from the rectifier plates to ground.

I have an SX-28 power transformer (Army Signal Corps stock) with the 115-230 switch on top which came NOS from Fair Radio Sales about 5 years ago... I think it may have been one of the last 2 or 3 they had (they'd catalogued them for years and years but the boom in SX-28 popularity dried the source up).  It has the 580 vct secondary, one 6.3 volt AC and one 5 volt AC filament windings.

If you have an actual SX-28 transformer there, the secondary is waaaaay too high and you might have a shorted turn in the primary someplace... but that should also make the filament voltages look strange.

Have you checked the current draw for the primary?  Wonder if you might have 230 volts poured into something set for 115....?

Halli used a number of transformers that looked alike, i.e. used the same case style as the one for the SX-28 (square top).  The SX-88 and SX-101 are two receivers; I think one or more of the transmitters had similar looking iron -- switch and all.  But no receiver would have used a transformer with over 600 volts on the full secondary if memory serves me.

73

Mike
W4DSE