Thread: Mystery OPT
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Don Pearce
 
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Default Mystery OPT

On Fri, 05 Aug 2005 11:15:17 -0500, flipper wrote:

I just received a pair of SE OPTs that were claimed to be from a
stereo console with 6BQ5 outputs. So far so good as that's precisely
what I wanted to build.

Problem is, when I put 120.7 AC on the primary I get 1.9VAC out for a
ratio of 63.5/1, which comes to roughly 32k/8 ohms, or 16k/4 ohms, and
from what little I know of 6BQ5 characteristics that doesn't make any
sense to me. I mean, 8K would be good but a console with 2 ohm
speakers?

Physically, the core is gapped with (actual core) dimensions of 2.25
inch wide by 1.74 inch high and .75 thick. Mounting is 2.75 centers
with 10A15-10 marked on the frame. Primary and secondary, 4 wires
total. No taps.

Does anyone have information, or an educated guess, on what these
transformers may really be or what I'm missing about 6BQ5s with such a
high OPT impendence?


These transformers sound an awful long way from optimum for a 6BQ5. I
think you were fed some duff gen.

d

Pearce Consulting
http://www.pearce.uk.com