>Subject: [AMPS] Alpha/ETO
>Sent: 4/08/1997 4:53 AM
>Received: 4/08/1997 7:16 AM
>From: Robert W. Stankus, RobertW@ewol.com
>To: amps@contesting.com
...snip...
>Two things separate amplifiers from the rest of the mickey mouse type.
I had heard that Disney was expanding into other fields.
>1. Bandswitch size and Pi-Network coils.
How true, Robert. RF current creates Much more I^2*R conductor loss than
60Hz current. A 30A at 60Hz rated switch may be barely adequate in a
1500w 160m - 10m amplifier.
>2. Weight of the plate transformer
Although weight has much to do with it, HV secondary R is probably a more
reliable indicator of a transformer's capability. I conducted an
experiment with a Hipersil-core HV transformer made by Peter W. Dahl.
This transformer had an extraordinarily low secondary R for the amount of
DC voltage it produced. The amplifier it was used in produced 190w of
PEP RF output for each pound of transformer weight. In SSB service,
after one hour, the transformer was warm to the touch. During speech,
the anode voltage regulation was about 6%,
--Shopping for a transformer? An ohm meter and a cliplead to short the
primary might be useful. For a discussion of how secondary winding R
affects DC regulation, see
*Amplifiers* at http://www.vcnet.com/measures
Some estimation formulas are provided which allow one to make a
semi-accurate determination of a transformer's current capabilities in
full wave bridge or full wave doubler, C-filter SSB service.
Rich---
R. L. Measures, 805-386-3734, AG6K
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