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Message-ID: <5.0.2.1.2.20011010184714.00a7c0b0@mail.pncl.co.uk>
Date: Wed, 10 Oct 2001 18:53:51 +0100
To: rsgb_lf_group@blacksheep.org
From: "Walter Blanchard" <blanch@pncl.co.uk>
Subject: Re: LF: Power Supply
In-reply-to: <Qse+eFAxT$w7MwU2@telemetry.demon.co.uk>
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At 08:12 10/10/01 Wednesday, G3OLB wrote:
>I recently opted for the 'Palstar PS-50' from Nevada which is a linear
>PSU giving 40 amps continuous, 50 amps intermittent, at 13.8V. It is big
>and heavy but economically priced and no noise. At least, there is no
>electrical noise but a slight audible hum from the transformer -
>something which you need to consider with a linear supply; a buzzing PSU
>can drive you nuts! One with a toroidal transformer should be quieter
>than one with a laminated one.

Tom, I also have one and it's fine until it gets a little hot and the fan 
cuts in. Then it sounds like a jet taking off.  I played with it quite a 
bit and eventually found that the best way round it was to rewire so the 
fan runs all the time on a reduced voltage just barely enough to start it 
and run - about 9volts.  That creates enough draught that the heatsink 
never gets much more than warm and the fan never needs to run at full 
power. Howver, I left the heat sensor connected so if it gets really hot it 
a relay switches it onto full 28v, but that has never happened yet even at 
25A continuous.

Walter G3JKV.