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??
To: <amps@contesting.com>
> 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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