Hi Bob,
E regulation will suufer considerably, especially with the amount of I you
are drawing. You do not getting something for nothing. You can increase the
primary power input with the autoxmfr but at the same time the amount of
available I will be reduced. This is a simple property of xmfrs. Plus the
autoxmfr is lossy. I would not go this route.
Swap out primary pwr xmfrs. If you go new it will cost. You need to check
the values used in the design. Some builders go overkill and leave you some
headroom to make changes. Others do marginal designs. You might not be able
to run the higher voltage and current safely. You need to look at what was
used in the PS and the RF deck.
Rich AG6K has some great info available on his web page. W6SAI's West Coast
Handbook is very good as well as the older ARRL Handbooks. There are others
on this reflector that can help more than I can. My experience is limited
but I built a "special" supply for my L4-B and during experimentation I ran
it with and w/o the Variac, I will NEVER run a rig using an autoxmfr.
Without the Variac using a Dahl xmfr Ep dropped 400 vdc from idle to full
power out of the amp. With the Variac Ep dropped 700 vdc from idle to full
power.
My two cents worth.
Good luck. : )
Lane
KM3G
----------
> From: K8MLM@aol.com
> To: amps@contesting.com
> Subject: [AMPS] USE OF AUTO TRANSFORMER
To: <amps@contesting.com>
> Date: Sunday, November 16, 1997 6:03 PM
>
> I have a home brew 4-1000 that requires more drive than my transceiver
(100
> watts) has to get full power out (it will only get 1000 watts out). The
> plate voltage is too low... about 3,800 volts. The power supply is
capable
> of pleanty of current ( about 1.5 amps DC at 3,800 volts continous), but
its
> maxed out on voltage. According to the book, the 4-1000 is operating
> correctly... power out for the drive and plate voltage.
>
> My question is this. Can I use a auto transformer to step up the
transformer
> input voltage to get a higher DC voltage output.... would like to operate
at
> between 4,500-5,000 volts? The auto transformer I have is rated for 240
vac
> in, 0-280 vac out at 28 amps.
>
> I've considered getting a different transformer with a higher voltage
rating,
> but since I have the auto transformer I thought it first.
>
> I believe I have seen some discussion here on the subject of auto
> transformers, but have been unable to find it.
>
> Thanks.
>
> 73, Bob
>
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