[AMRadio] Resonant Choke for HV PS

John Lyles jtml at losalamos.com
Mon Oct 1 00:54:14 EDT 2007

I recognize my dribble there, to update it, Carl Sievers of SNC retired few years ago, and passed away. He was a great transformer engineer. 
For the fellow trying to build one, its not so important that the bleeder R be chosen to keep constant current through the choke throughout the rectification cycle, if you use a resonant choke. The whole point there is design a choke which has a very high impedance at the ripple frequency, as a big L would. Once you reach the critical inductance, for a given bleeder current, you don't need to go futher. Any old ARRL handbook or other text on power supplies covers that. Having a very high impedance (as the parallel LC would be at resonance or near so) means the bleeded current can be much much smaller. If you design this power supply for an amplifier which always has idling current of some minimum value, then theoretically no bleeder is needed, except to discharge the caps when it is switched off. 

> I found this discussion on another list, but it covers (in depth) choke 
> input power supplies and tuned chokes, which is what I think the 
> Original Poster was trying to do.
> *I* didn't write it, but it's -great- technical information for the 
> archives.
> ~~~~~~~~~~~~~~~~~~~~~~~~`
> Since you asked for a core dump on tips for building a resonant L section
> in a power supply filter, here it is. My own experience with resonant choke
> comes from 1982. I also spent considerable time working with Carl Sievers
> (now retired) of SNC transformer in Oshkosh, WI, along with another old
> timer there who had designed one for a Heathkit amplifier (was it the
> Warrior?). They shared their experience with me. At the time, I may have
> built the highest power resonant choke input attempted. Maybe not, speak up
> if anyone did it.

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