[Amps] RE: 4CX250B Screen Supplies

[R.Measures]

On Jul 25, 2004, at 7:38 AM, DF3KV wrote:

>>    In the amplifier I am currently building, I will be using an
>> electronically-UNregulated resonant-choke 1500V screen PS.  The
>> resonant choke is 9H//0.2uF and a filter C that is seemingly too
> big.
>> The logic here is that since both of my previous "plywood box" ugly
>> amplifiers used electronically-regulated screen supplies -- which
>> proved to be the most delicate part of the machine, something
> simpler
>> might be worth a try.  Thus, extra filter-C is an attempt to
> minimize
>> voice modulation IMD.  With luck, the result won't suck.  If it
> does, I
>> will go to a higher tap on the transformer and electronically
> regulate
>> down to 1500V with the + floating regulator shown at
>> http://www.somis.org/D-a-08.GIF cheerz
>> end
>
> Hi all,
>
> pretty good experience with screen powersupplies  for large tetrodes
> with handles  are  built overhere with 3 single bridge rectified
> powersupplies fed by 3 phases and paralleled  at the output, very
> stiff!

Indeed, Peter, and a resonant-choke filter for the 300Hz ripple-freq of 
50Hz 3-phase needs only around  3.5Hy and 0.08µF instead of the typical 
9H and 0.2µF used for 60Hz, 1-phase's 120Hz ripple-freq.
end

Richard L. Measures, AG6K, 805.386.3734.  www.somis.org