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Re: [Amps] Most power ever run on amateur radio :-)

To: <david.kirkby@onetel.net>, amps <amps@contesting.com>
Subject: Re: [Amps] Most power ever run on amateur radio :-)
From: Karl-Arne Markström <sm0aom@telia.com>
Date: Wed, 26 Dec 2012 20:44:50 +0100 (CET)
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Normally, a 10 - 15 kW output amplifier such as the Collins 208U-10 or 
the Harris RF-126 requires primary fusing using at least 63 A slow-blow 
to be able to cold-start without risking the fuses (assuming a very 
"stiff" 380/220 V AC mains supply).

It seems however that a large part of the starting current in these 
amplifiers comes from the blower.

By using a separate time-sequence relay to start the blower a few 
seconds after the HV supplies, I have witnessed the successful 
operation of a 208U-10 from an rural AC mains using 25 A slow-blow 
primary fuses.

I would say that the Italian amateur mentioned is taking some serious 
electrical safety risks by using his neighbours phases
to feed his amplifier. A short to ground may raise the neutral 
conductor potential for the whole area in unpredictable ways.

73/
Karl-Arne
SM0AOM



----Ursprungligt meddelande----
Från: david.kirkby@onetel.net
Datum: 2012-12-25 01:24
Till: "amps"<amps@contesting.com>
Ärende: Re: [Amps] Most power ever run on amateur radio :-)

On 20 December 2012 00:55, Manfred Mornhinweg <manfred@ludens.cl>
wrote:> About two years ago I was contacted by an Italian ham, who
wanted my advice
> about how to wind a three phase high voltage power transformer for 
his amp.
> He reported that he was running 45kW, and that lacking an actual 3-
phase
> connection, he was using one phase out of each of two neighboring 
homes
> (good neighbors!), and his own phase.

Yes, very good neighbors!

I'm lucky in having a 3-phase supply to my house - unusual in a
domestic property, but the house used to have night storage heaters,
which use a lot of power if you have enough of them.

But even with my 3-phase supply, I could not run some of the powers
being talked of here.

I imagine if you had enough lead-acid batteries, you could run the
linear from them, but charge them up when not using the linear. That
way the peak current consumption would be reduced. An expensive way,
and would making working on the HT supply even more dangerous than
usual!

Dave, G8WRB
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