A fairly common occurrence is when the

capacitor shunting the high voltage choke

in the Henry swinging choke design changes

value and does not resonate at the 120 hertz

intended? frequency.

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I challenge you to remove the oil-filled

resonant capacitor shunting the choke and

to accurately determine its actual capacitance.

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Using the specified component values in the

amplifier parts list, compared to the value(s)

printed on both the choke and the capacitor,

see if any of the printed values correspond.

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Next, check the oil-filled cap.

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One way is to use the formula for determining

the capacitance value for the shunt cap in a

swinging choke input filter and see if the actual

measured value is the same as specified.

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Additionally, using the formula for resonant cap and

choke values, plugging in the measured values you

observe, determine the resonant frequency of the

small network on your bench.

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My question is how will you obtain an oil-filled cap

with the same ratings as needed to achieve 120 Hertz?

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Please remember these capacitors do not live forever,

and that they must have a WVDC rating sufficient to

carry the amplifier’s Anode High Voltage.

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Respectfully,

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Hal Mandel

W4HBM