[Amps] 4CX250B in grounded grid and screen configuration

[Radio WC6W]

Hi Angel,
  That connection is not valid for the 4CX250 family.

  The control grid will hog the current and self
destruct.

  To run these types cathode driven, the standard bias
voltages must be applied to the grids which may then
be RF grounded via bypass caps.  

73 & Good morning,
  Marv WC6W


--- Angel Vilaseca <avilaseca at bluewin.ch> wrote:

> Hi,
> I have several used 4CX250Bs that I want to try to
> put to use.
> 
> State of the tubes is unknown. They are pullouts. I
> will test them 
> including hipot, as was detailed on this list a few
> days ago.
> 
> Now if some pass the hipot and other tests, there is
> still the secondary 
> emission problem with an used valve of this kind.
> 
> So I was wondering if would be possible to use a 4CX
> 250B with both its 
> grid and screen connected together to ground.
> 
> Will it behave as a grounded-grid triode?
> 
> Will then secondary emission still be a problem?
> 
> How many 4CX 250Bs connected in parallel woul it
> take to have a cathode 
> circuit with a reasonable match to a 50 Ohm input
> drive?
> 
> Vy 73
> 
> Angel Vilaseca HB9SLV
> 
> 
> 
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> 



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