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Does this tell any or you about the tranny? Is there a way to measure the impedance?
The only thing I could find on the web said it might be from a Peavey classic 30. Perfect, only I think the tranny is older than that.
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The 705...number is probably the part number. You aren't likely to get lucky with a lookup on this, but it happens. I had a very old PT from a company that is still in business. Somebody took the time to find the specs for me. It was amazing. I was also very lucky and expect that was my "one time".
You will need to determine the turns ratio. I like this article:
Typically, I use a filament winding from a power transformer. If it's got a 5V winding or a 6.3V winding, either is fine. You can also use an AC wall wart if you have one, though these are not as common as the DC wall warts. Remember that actual voltage will vary at the wall socket and when the source transformer is under load. So check the source voltage and the output voltage. Do the math and you will know the relative impedance on the primary and the secondary. It might be difficult to determine if you have a 4K primary and a 4 ohm secondary or a 8K primary and an 8 ohm secondary, but chances are you will get to an answer that works.
The size of the core will suggest rating for number of watts. This is a judgment call unless you go through a battery of more complex tests to get all the info you need. I imagine that most people (me included) don't have enough test equipment to do this.