[AMPS] Screen regulator circuit needed

[Rich Measures]

>Series pass stabilisers do not absorb the negative screen current that 
>tetrodes typically generate.  Using a series pass stabiliser causes the 
>screen voltage to go up and down in sympathy with the negative and 
>positive screen current, which can cause the tube to flash-over with 
>spectacular results!

Not if one uses the recommended amount of screen bleeder current.  [see 
Figure 5 on my Web site].  For tetrodes with handles, which typically use 
1.5kV screen potentials, shunt regulators are neither practical nor 
energy efficient.  
>
>The only safe screen stabiliser is a shunt stabiliser.  This can be made 
>using either mosfet's or bipolar's, the tv industry has some good (cheap) 
>devices which can safely handle 1500V.  Today the tube shunt stabiliser is 
>a bit of an oddity, but they can still be made to work, but transistors 
>are a better choice.
>
>John    ZS5JF
>-----Original Message-----
>    From: Rich Measures <measures@vc.net>
>    To: Bill Coleman <n2bc@ibm.net>; amps@contesting.com 
><amps@contesting.com>
>    Date: Sunday, November 15, 1998 3:34 PM
>    Subject: Re: [AMPS] Screen regulator circuit needed
>    
>    
>    
>    >
>    >I'm wrestling with trying to get a couple of 811s and a string of VR 
tubes
>    >working as a regulator on a 1KV screen supply for a 4-1000 in AB1 (early 
60s
>    >handbook circuit). 
>    
>    €  One needs triodes with a Mu of under 5 for pass regulator service  .
>    
>    >I picked this circuit because I had the 811s. So far I've
>    >succeeded in building a nifty 200W or so LF oscillator (big surprise)

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