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Old 24th September 2011, 07:04 AM   #1
dgta is offline dgta  United States
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Default Help ID this OPT

Medium size OPTs, silvery grey end bells, numbers 200A1 and 549821 stamped in very small letters in the end bells. Medium size, PP, UL taps, definitely old, cloth insulation on wires.

Would appreciate any info, particularly specs.
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Old 27th September 2011, 05:34 PM   #2
dgta is offline dgta  United States
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Bump.
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Old 27th September 2011, 06:05 PM   #3
sreten is offline sreten  United Kingdom
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Hi,

I guess you could work out the turns ratios by applying 110VAC to the
primary and measuring secondary AC voltages, impedances are the
square of that ratio with 8R load. Very likely though they match EL84's
/6BQ5's or EL34's/6CA7's going on the UL taps, size should indicate which.

rgds, sreten.
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Old 27th September 2011, 08:25 PM   #4
Zibi is offline Zibi  Poland
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? Ham Radio Audio Amp Tube Input Transformer Thordarson
Antique Transformer and Parts Catalogs and Specifications
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Old 27th September 2011, 08:44 PM   #5
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Probably better to use a lower AC test voltage from the secondary side of a power transformer - as some people may think that they could use the AC mains as a test voltage, which would not be a good suggestion at all.

Ciao, Tim
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Old 27th September 2011, 09:01 PM   #6
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by trobbins View Post
Probably better to use a lower AC test voltage from the secondary side of a power transformer - as some people may think that they could use the AC mains as a test voltage, which would not be a good suggestion at all.

Ciao, Tim
Hi, Unless its faultly pray tell why not ? rgds, sreten.

Same issues as testing mains transformers, if they work no issues.
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Old 27th September 2011, 09:40 PM   #7
dgta is offline dgta  United States
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Guys, I did measure the impedance, that's not what I'm asking, but thanks anyway.

I want the spec sheet.

OK, after much search I determined 549 is the code for Midwest Coil & Transformer Company. The last 3 are the date, the 21st week of 1958, 1968 or 1978 (the "8" digit).

Now with this info, does anyone have any info, catalogs or links to same for the specs on this particular transformer? Thanks.
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