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Re: KPA 500

Posted by M0XDF on Feb 06, 2011; 9:48am
URL: http://elecraft.85.s1.nabble.com/KPA-500-tp5995970p5997308.html

I get 240 +- 2v here in Bracknell in Berkshire.
73 de M0XDF, K3 #174, P3 #108
--
No sensible decision can be made any longer without taking into account not
only the world as it is, but the world as it will be.
-Isaac Asimov, scientist and writer (1920-1992)

On 6 Feb 2011, at 09:36, David Cutter wrote:

> I can't speak for other countries, but here in the UK I used 240V +-7%
> (223V to 257V) for normal service but for brown to peak I used 240V +-10%
> (216 to 264V), which is very rarely seen here.  The 264V is used to test
> safety trips and the like according to British Standards such as the the
> generic BS3456.  Factoring Europe into the equation, I reduce the lower band
> to 198V (220 - 10%), so, my designs covered 198 to 264V for safe and
> reliable operation.  In practice, the lower end often extended to 186V
> (-15%).  This puts quite a burden on dissipating heat at the top end when
> using linear supplies, but is the penalty when designing for extremes if
> switchmode cannot be used. Hence tapped transformers to cope with local
> supplies.
>
> Being aware of this, I have always been wary of generators when /P or
> dxpeditioning and with valve linears getting the heater voltage right with a
> true rms voltmeter has always been a concern for me.  Small generators often
> produce more of a triangular waveform and are poorly regulated well beyond
> +-10% key up to key down.  With a transistor linear I am concerned about the
> peak of the triangle which is higher than that of a sinewave of the same rms
> voltage, so, component ratings are very important.  On full load, the
> problem is distortion as the incoming voltage drops.  Some generators also
> slow down, increasing the ripple triangle and current into the reservoir
> caps.
>
> David
> G3UNA
> My previous email on this didn't appear on the list, perhaps stuck in
> cyberspace.
>
>
> snip from Juergen
>
>
> Hi Albert
>
> The old standard of 220,230,240 volts +- 10% has been gradually
> deteriorating to plus minus anything!
>
> The mains voltages  in many places now goes up to and regularly runs at 260
> volts! The global de-regulation and privatization of power assets globally
> has seen standards  go down the drain everywhere.
>
> Most quality switch mode power supplies are designed for voltages   as high
> as 260 high volts with a plus 5% rating. Many designers and export countries
> have not caught up with the global deregulation of mains voltage standards.
> In many places this has been allowed to happen in the hope that a global
> standard will develop.
> .
>
> 73
> John
>
>
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