>> Thanks for the info so far. Additional info is as follows: The
>> transformer was designed to be used with a doubling rectifier. The
>> secondary is 900 volts +or- 5%. The secondary resistance is 16
>> Ohms. (primary will be wired for 240V).
>Ouch Kurt!! That is very high resistance, because the secondary
>ESR (equivalent series resistance) will be substantially higher than
>the secondary dc resistance. The actual resistance seen by the
>rectifiers and capacitors will include 16 ohms plus core losses and
>primary/power mains resistances!
>You want to use a conventional (full-wave) doubler, and not a
>cascade (half-wave) doubler. Cascade multipliers have less
>regulation and more ripple, and are mostly used where one side of
>the source is grounded or you need high multiplications.
>Doublers are actually just as good as bridge rectifiers IF the
>transformer is the same size and fully optimized. It does not sound
>like your transformer is sized for four 572B's at all.
>Assuming you have 2500 ohms of DC load resistance from the
>tubes (1600 watts tube input power), and 30 ohms of ESR (which
>is reasonable for a 16 ohm DC resistance secondary when used on
>a very stiff power line) and 2 ohms of secondary ESR caused by
>the capacitors and power line resistance, around 80-100
>microfarads will be optimum.
// The Heath SB-220's HV filter is 50uF per half of the FWD, or 25uF
total. The 220 does c. 2800v @ 800mA-peak with no apparent problem.
>The voltage will be 2500 volts no load and almost certainly well
>under 2100 volts full load. Any amount of capacitance above 80-100
>uF (for each half of the series string) will NOT improve things.
- R. L. Measures, 805.386.3734, AG6K, www.vcnet.com/measures.
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