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At an estate sale today, I picked up what appeared to me to be a large tube amp power transformer, in unknown condition, basically for free. It was a HUGE sale at the house of a man who had collected all sorts of gear and had most of it carefully boxed and cataloged. He was into both audio and film--had a home theater built into his house. Often power transformers are removed because they're bad, but this one had been very carefully removed and stored--with no markings, unfortunately. EIA code 141 shows it was made by "Coil Engineering." It looked like it had a CT B+ winding, a 5V winding, and a 6.3V (green wire). The transformer is the same size as the improved Dynaco ST-70 transformer sold by Triode Electronics.
I carefully powered it up with a fuse to see if it was blown. No fireworks. I measured 216-0-216 on the B+. Then, on the other windings, I got 2.9VAC and 3.9VAC (unloaded) where I was expecting 5V and 6.3V. That's when I started wondering if this was a 240VAC power transformer removed by this collector when he converted some piece of 240VAC equipment he bought to 120VAC.
Does that sound like a good guess?
I carefully powered it up with a fuse to see if it was blown. No fireworks. I measured 216-0-216 on the B+. Then, on the other windings, I got 2.9VAC and 3.9VAC (unloaded) where I was expecting 5V and 6.3V. That's when I started wondering if this was a 240VAC power transformer removed by this collector when he converted some piece of 240VAC equipment he bought to 120VAC.
Does that sound like a good guess?
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