[Amps] 8122

[Peter Voelpel]

Hi Manfred,

The 6146 (QE05/40) which is a beam power tetrode has 20W allowable
dissipation in CCS service.
According to my Valvo tube manual idle current at 750V is 12mA, that is 9W,
almost 50% of dissipation.
The 813 (QB2/250), also a beam power tetrode with 100W dissipation is
specified at 25mA/2KV for AB1, that is 50W.
Burle data for the 8122 is 100mA idle current at 2KV which is 50% of its
400W maximum dissipation.

73
Peter

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Manfred Mornhinweg

> High idle current is normal in most tetrodes,

But why? Looking at old 100W transceivers with 6146 or TV sweep tubes, they
all (to the best of my knowledge) use low idle current. And an 813 amp I saw
also does. Is that because these are pentodes? If so, why does a tetrode
need higher idle current?