In my current project, a dual 3CPX800A7 triode
multibander, the outboard power supply was a
"must," because of the elevated capabilities of
the finals and so I decided upon an anode
transformer from Tom Hand that delivers
2200v.a.c. @ 2 amps, CCS.
In designing the rectifier and filter the
Handbook formulae for determining the
filter capacitance value to give less than
3% ripple voltage was the guideline for
choosing the capacitors.
If you refer to the several formulae, you will
see that the percentage ripple is the E/E * 100,
and the Ripple voltage is a factor of
7.5mS *I-sub-Max, divided by the Anode Voltage.
The whole thing resolved into a table where the ripple
didn't go below 3% until the filter capacitance
exceeded 100uF. (Actually, it was 104uF at the
3% crossing).
Please remember the filter is a capacitor-input, no choke.
My question to the group is twofold:
If the Handbook stresses less than a 3% ripple on
tube anode supplies, how is it we see commercial
supplies with a fraction of the needed capacitance
to achieve this regulation?
Secondly, since the needed capacitance to go from
let's say 4% ripple to 3% ripple or below represents
hard dollars for the stressed builder, what level of
ripple on anodes in the HF class of AB2 amplifier
is acceptable, and why?
Respectfully,
Hal Mandel
W4HBM
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