On 4/21/16 9:27 AM, Bert Hickman wrote:
Gary and all, Part of the problem (with NST's at least) may be due to the internal current limiting shunts which reduce the effective coupling coefficient. This will cause the measured voltage ratio to be somewhat different than the actual turns ratio. A more accurate approach might be to drive the LV side from a small variac and then monitor the secondary voltage using the HV setting on a DVM or a cheap analog meter. Or, use a simple resistive or capacitive HV divider and a high-input impedance DVM. Driving the LV side at 10% of its normal operating voltage should provide sufficient MMF to make the core happy, while reducing the output to a lower, and safer, level.
I use a 12.6V filament transformer for this kind of thing.I started to build, but never finished, a little battery powered 60Hz source at about 10V for testing in surplus shops, scrapyards, and the like. You see that unmarked transformer, and it looks about right from a size standpoint, but you need something to test with. ALso handy for checking out big capacitors.
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