On 05/06/2021 01:03 AM, gudguyham via Amps wrote:
Some of the old Henry amps actually require a neutral to be present when using the amp on 240v. On 120v it
makes no difference because if you have two wires, hot and neutral (120v) the neutral is available. When
switching to 240vac if you lack the neutral, they instruct you to use ground to carry the fan, and low voltage
transformer neutrals. This practice is NOT good and could be dangerous. The neutral that is required
is hooked up to a separate terminal at the rear of the amp, this is the neutral being sought out by the fan and LV
transformer. The simple fix which satisfies all conditions is to NOT use ground( the green wire) to this
terminal as a neutral, but rather use a jumper wire at the two terminals that series up the dual primary to that
terminal. By doing this there is no need for an external neutral and the green wire can be used as
chassis ground as intended.
If I correctly understand what you are saying, this is exactly what the Alpha 76
and my old B&W PT-2500A have done. They have dual 120 volts primaries that they
put in series for 240 operation. 120 volts for the blower is derived from one
side of a 120 primary and the "center tap" between the two 120 volt primaries.
73,
Steve, N2IC
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