[AMPS] 572-B Input impedance??

[John Fielding]

Hi all - I downloaded the Svetlana data sheet on the 572B so I could study it.  Some
interesting facts came to light.

grid to plate = 6.0pF
grid to filament = 5.9pF
Plate to filament = 0.8pF

I guess if the grid isn't totally, solidly, held to chassis and everything else using low
inductance grounding then this tube will make a superb oscillator!!  Almost perfect as a
Colpitts power oscillator.

BTW  Svetlana gives the Fmax as 30MHz for full ratings.  SOOO for 50MHz applications,
figure on derating it by about 50% if you value your tubes.

IMHO not a good choice for 6m.  I know Carl KM1H will disagree, but he hasn't been around
for a while.  What happened to him?

John	ZS5JF



----------
> From: Peter Chadwick <Peter_Chadwick@mitel.com>
> To: W8JI@contesting.com; amps@contesting.com; drpal@waterw.com; 'Rich Measures'
<measures@vc.net>
> Subject: RE: [AMPS] 572-B Input impedance??
> Date: 26 July 1999 10:28
> 
> 
> My experience with 572s suggests that operation at 50 MHz is going to be
> interesting from a stability point of view. The grid leads are just far too
> long for operation up there. Series tuning might help, but what the
> efficiency will be is another matter. I'd use something else.
> 
> 73
> 
> Peter G3RZP
> 
> 
> 
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