Thomas, in my 4-1000 grid driven amps I faced a similar dilemma 20 years
ago. Using the HV to drive the screen supply seems like a great idea, since
if the B+ goes down, then the screen does too, preventing screen damage, but
the thought of a 400W resistor bank was rather daunting, not to mention the
added heat and wasted power. I ended up building an ordinary well-filtered
600V FWB using a 450V transformer rated about 1/2A, and bled it with 12K,
50W resistor, creating a self-regulating screen supply that is so stiff it
doesn't budge regardless of what the tube does. It's been working 20 years
now (this month). Still using the same tube, same PSU components, same
everything. Haven't had the cover off the 4-1000 6m amp since May 1984 when
I first put it on the air. -WB2WIK/6
"Success is the ability to go from failure to failure with no loss of
enthusiasm." -Winston Churchill
> -----Original Message-----
> From: Thomas Hoeppe [SMTP:thomas.hoeppe@asamnet.de]
> Sent: Wednesday, May 12, 2004 11:35 AM
> To: amps@contesting.com
> Subject: [BULK] - [Amps] Screen voltage regulation
>
> Hello guys,
>
> I am new on this reflector, so may be I am asking a question whitch has
> been discussed before.
> I am looking for a simple design for the regulation of a screen supply. I
> need 800V and about 50 mA. I will have to take care of some negative
> current, so the supply has to be able to do that or I will use a 100mA
> supply and allow 50 mA of current through a resistor to ground. My anode
> voltage is 5 KV, so I don't want to get the G2 voltage from the anode
> voltage.
>
> I am looking for easy and rugged solutions. (KISS.......keep it simple and
> stupid!)
>
> Any ideas?
>
> Thanks in advance.......
>
> Tom, DJ5RE (DL0AO crew)
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