RE20 Transformer Dissection (old style)

[MicDaddy]

it seems the hosting for these photos went down, once I find them I'll post again

 

[CJ]

nice work! 
where is that transformer used?

 

[MicDaddy]

Thanks CJ, you've inspired this.

The transformer is the output for the EV RE20 microphone (the old style, new ones are different few times over).  Has some feedback/tertiary going on for corrective eq and I'm trying to wrap my head around that.  Trying to get the maths in the right place to forecast where the q point will land and just how deep of a dip we get. 

Only E in the stack, laced 1x1, 18 total lams 9 each side.  Looks like high nickel content alloy.

This thing is pretty loosely wound, "wild winding" is the perfect term.  Actually kind of shocked how "careless" it appeared to have been wound... perhaps I'm a bit too hard on myself.  But how do they get nice flat responses with such a "sh*tty-looking" coil structure??

I was anxious to tear into the thing and didn't grab many bits of info that I probably should have.  Voltage ratio etc, primary inductance at 20Hz, some more dimensions of the lams.  My caliper isn't the greatest for measuring the magnet wire, I think a micrometer might just smash it.  Best guess at AWG is #30 primary & #36 secondary.  (didn't think until now to measure a given length vs resistance and take that to the charts... hmm)

Lots of room left on the bobbin, might try to bump the gauge and lower DCR, not sure what to expect... will have to read more into the transformer books but something about excitation and non ideal transformers... so a larger gauge will have a lower DCR and possibly not so much offending excitation?  Ok back to the books...