[Amps] What to do about 'Neutral' in HB amp?

[gudguyham at aol.com]

As wired in the schematic the old Alpha 70/77 would never get a UL listed cert.  although built before the NEC rule that’s a moot issue.


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On Wednesday, December 28, 2022, 10:13 PM, Paul Christensen <w9ac at arrl.net> wrote:

>"If you have an old Henry, when switching to 240 without the required neutral available you simply add a jumper to the terminal strip that ties the primaries together to the terminal looking for the neutral.  That makes everything happy and is safe and legal. "

That's a good solution and it's a common method used with several other amps.  It's a bit trickier with the Alpha 70/77 series because ETO deliberately designed the blower in series with the HV primary.  As power demand increases, primary HV current increases, resulting in dynamically faster rotational blower speed.  To preserve that characteristic, I ran 4-wire service to the shack.

Paul, W9AC

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