----- Original Message -----
From: "Manfred Mornhinweg" <manfred@ludens.cl>
To: <amps@contesting.com>
Sent: Sunday, October 13, 2013 3:09 PM
Subject: Re: [Amps] AL-800H transformer
Hi Paul,
I was thinking I could wire the primary as 250VAC input i.e. put all
primary windings in series and supply it with 110VAC input which
should drop the HV output to less than half.
What doe the experts on here say?
It's right - when you apply half the input voltage, you get half the
output voltage. The magnetic flux in the core will be halved too, so that
the core will have only about 30% the loss it would have at full voltage.
But the current handling ability is the same as at full voltage. This
means that the power output it can produce, at half the voltage, is also
only half its rating. And the voltage drop at that load will be as much as
at the full voltage, so that the percentual stability of the output
voltage under load changes is only half as good as at full voltage.
Since you need just 400mA, that transformer should work OK. It can hardly
have been designed for much less than that current. Just be aware of the
lower voltage stability, compared to a transformer optimized for the
voltage you need.
Manfred
With much lower core loss and less than half the primary power and half the
secondary power consumed the regulation should be much better than the 15%
Ameritron rates it at in the 811H.
In intermittent duty at half voltage you should be able to pull a bit more
current at that 15% regulation but temperature rise should be measured
first.
Carl
KM1H
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