[Boatanchors] Bucking Autotransformer - use as combination bucking and isolation?

[Ben Hall]

Good afternoon all,

I recently picked up a bucking transformer off of the e-place for pretty cheap...as it was missing the bottom close-out panel and was used.  After some CAD work and 3D printing of a replacement...it's good as new.  ;)

Transformer is an Acme Electric, model T181051, as described in the below page from Automation Direct:

<https://cdn.automationdirect.com/static/specs/acmebuckboostxfmr.pdf>

This is a 500 VA rated transformer.  Scrolling far down in the attachment above...this unit when used as a standard power transformer (120 VAC in, 12/24 VAC out) is rated at 41.6 amps with both 12 VAC secondaries in parallel, and 20.8 amps with both 12 VAC secondaries in series for 24 VAC out.

When connected as a 125 VAC input, 113 VAC output bucking autotransformer per hook-up diagram F on page 12 of the PDF, it's rated at 46.8 amps.  Quite overkill for a 15 amp mains powered boatanchor receiver!

So I got to thinking!  Could I wire it as both an isolation and bucking transformer?

IE:  Feed 120 VAC AC mains into one primary (say connections H1 and H2), then use the other primary (H3 and H4) as an isolated 120 VAC output?

Then, using that isolated output from H3 and H4, then hook-up say the X1 and X2 secondary out-of-phase to get 12 VAC of bucking on that isolated 120 VAC output?

I can't think of why this won't work.  YET, I can't find anything after some google searching saying it works or it's a dumb idea.

I do know that I lose some efficiency in the standard, non-autotransformer bucking configuration, but since this transformer is so much larger than what I need, not sure I really care too much?

So what do y'all think?  Dumb idea?

Thanks much and 73,
ben, KD5BYB