Terry Given wrote:
[snip]

I design lots of magnetic devices. One of the first things I do with a
prototype transformer is dismantle it - I look at insulation, wire type,
winding pitch etc, AND I specifically count the number of turns (my
Leatherman has gutted hundreds of transformers I also measure coupling,
saturation, DC resistance, capacitance etc

If I had 2 of those bobbin core coils, I would just unwind the damn thing
and count the number of turns.

Ultimately, pay attention to John Larkin. A mate once had a 3-phase inductor
made (for a 600kW Butterworth filter that was hopeless - fringing flux
and leakage totally ruined the current distribution, making it glow red hot.
OTOH it made a great heater

Is this a movie of that "heater"??? :-))) (Warning: 5 Megabyte .MPG)
http://205.243.100.155/frames/mpg/XfrmBlast1.mpg

Cheers
Terry