[Amps] Switch-mode HV power supply

[Ian White, G3SEK]

Oleg Skydan wrote:
>
>Here is the URL:
>http://www.qsl.net/dl2kq/pa/1-1.htm
>
>It is in Russian, but there is a button (in the upper-left corner of 
>the page) for on-line translation.
>
The translation engine wouldn't work for me on Saturday... probably too 
many people using that site to look for a wife :-)

Fortunately, the schematics for direct voltage multiplication from the 
mains turned out to be on the first of the pages in Russian.

When I started this discussion, I should have said that one of my 
criteria for choosing a PA is that it should give a significant increase 
above 100W. It really doesn't seem worth the trouble of adding a PA to 
your 100W transceiver - and it *certainly* isn't worth the trouble of 
taking a PA on a DXpedition - unless it is capable of at least say 400W 
output, and preferably much more.

By rectifying and multiplying 230/240V, it is quite difficult to develop 
much more than 1kV, and that is only enough for an amplifier in the 
100-200W class. The Russian page shows an example of a GI7B; and even 
for that tube, 1kV is very low. If you tried to voltage-multiply by 
higher factors, you'd run into severe problems with smoothing and 
ripple.

Also, half of the total HV is positive above ground; and half is 
negative below ground, which creates some serious conflicts between 
safety and good RF grounding practice. And as for the power supply 
design... well, let's just say I wouldn't touch it!


-- 
73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)

http://www.ifwtech.co.uk/g3sek