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

[MU 4CX250B]

Paul, I don’t understand this. The blower surely isn’t in series with
HV primary. How could that work?
73,
Jim w8zr

Sent from my iPhone

> On Dec 28, 2022, at 8:13 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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