Uher Z131 PSU loud transformer buzz - Page 3 - UK Vintage Radio Repair and Restoration Discussion Forum

ms660 · 7th Aug 2021, 3:27 pm

Quote:

Originally Posted by DMcMahon

Are you expecting that the Loss Balance setting will increase for a tuned null when series resistance is added ?

I would have thought so, shame I haven't still got mine otherwise I could muck in with some measurements.

Lawrence.

DMcMahon · 7th Aug 2021, 11:53 pm

Quote:

Originally Posted by Radio Wrangler

Quote:

Originally Posted by DMcMahon

Maybe, I say maybe because I do not fully understand it.

It has a rotary potentiometer used with a 3 position D-Q switch that are used as Loss Balance controls (they have no effect in resistance mode).

If you had a known good inductor to practice measurement on, you'd set the loss knob to zero and twiddle the big knob which in this range measures inductance. BUT you will find the null is neither very deep nor sharp. Find the rough middle of the dip, and now play with the loss knob. Your null should get deeper. Keep alternating between knobs and giving them a careful twiddle and you should get a deep notch. You can read off the inductance and the loss factor/Q and feel a bit more confident about things.

David

Been trying to locate a known good inductor of known value to practice on but not finding it easy to find one.

David