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Old 24th Jun 2021, 7:32 am   #1
trobbins
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Default Unknown output transformer in early Williamson amp

Anyone identify the maker of the output transformer in the photos from an early Williamson amp? The photo of the amp chassis shows the OPT as the plain boxed transformer on the LHS (not the taller sculptured PT on the RHS). The terminal plate shows the expected terminal markings, and also appears to show ? OHM and ??CS. There were a few output transformer manufacturers advertising in WW, but the photos don't identify the manufacturer.

By exclusion it isn't a Partridge, Woden WOT25, Gilson WO1796, or Gardeners OP736. I don't have any photos of the Elstone MR/W, Savage or Vortexion to compare, and I guess there were a few other UK makers at the time.

Ciao, Tim
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Old 24th Jun 2021, 7:44 am   #2
joebog1
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Default Re: Unknown output transformer in early Williamson amp

I may be wrong, BUT it could be one of the "select" transformers made in Australia. I had a 6BQ5 push pull amp with identical (if very much smaller) made by I believe Ferguson. It was totally potted inside the box. The bottom of the box was likewise soldered into the "case" which was I think tinplate. The nastiest thing about it was that the mounting screws were Aussie made Whitworth, non plated steel screws.

The amp I am speaking of was a Radio, Television and Hobbies version of the GEC amplifier in the back pages of the English textbook, I "think" called the Radio Engineer's Handbook. 6BK8 input, 12AX7 phase splitter, and a couple of 6BQ5's as output. It's just that the construction of that transformer in your pic is identical.

Just my observation.

Joe
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Old 24th Jun 2021, 9:07 am   #3
GrimJosef
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Default Re: Unknown output transformer in early Williamson amp

The terminals look like wires trapped under screws and the labelling is done slightly wonkily with a set of hand number-punches. I wonder if it's home-wound ? The original Williamson article included the exact winding details to allow readers to do precisely that.

Cheers,

GJ
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Old 24th Jun 2021, 12:57 pm   #4
trobbins
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Default Re: Unknown output transformer in early Williamson amp

Joe, the amp is presently for sale in the UK and all the parts appear to be of english origin.

Both transformers may not have been original (certainly the PT looks like it has been replaced), and the construction looks a bit like a kit or DIY from parts and a chassis that has been modified to suit. The amp does look like it could be late 1940's. It would have been a keen DIYer to prepare that terminal plate, but yes GJ it looks too unprofessional to have been made by a larger maker.

It's a bit uncommon to see such an output transformer.

Last edited by Cobaltblue; 24th Jun 2021 at 1:31 pm. Reason: Rules C2 and 3
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