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Re: Low Hy? How about no Hy?

Posted by Eli Duttman on May 5, 2007 at 20:03:59:
TK,
I don't know what kind of H/K power "iron" is on your "pile". However, I DO know what works in a doubler PSU. Follow the general setup in a Jim McShane overhauled H/K Cit 2. Low noise SS diodes into a pair of HIGH value, low ESR, 'lytics. A low DCR choke follows the doubler stack. Follow the choke with additional capacitance of substantial value. The choke primarily kills "hash", not the ripple fundamental. "Hash" comes from SS diode switching noise and ripple overtones related to the highly triangular wave form large caps. yield. DC B+ draw must be limited 0.25X the AC RMS current capability of the rectifier winding.
FWIW, we use the same 820 muF. 'lytics in the "El Cheapo" doubler as Jim uses in Cit. 2s. It's a cost containment measure related to economies of scale. The "El Cheapo" doubler is quite stiff and the ripple freq. fundamental level is low, but there's plenty of overtone "hash". The replacement choke targeted at Dyna ST70s makes short shrift of that crud. Even a "Bargain Basement" project has to have a QUALITY PSU.

Eli D.