[Elecraft] KPA 500

[David Ferrington, M0XDF]

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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