On Sep 1, 2004, at 8:22 AM, Jim Isbell wrote:
This is EXACTLY the answer I needed. The amp uses a pair of 4-125As
and the screens are at "350V - 400V" Plates at "2000V - 3000V" (but
no terminating resistor) so I guess that makes it a class AB1 linear.
Jim -- Class AB1 amplifiers always have a grid-terminating R because
the grid draws zero current. .
The screen grids have several bypass caps to ground but no resistor.
A shunt resistor is needed to sink reverse screen-I. Typically, about
25% of normal screen-I is shunted by this resistor.
The signal is fed to the control grids through the MB-40-L and the
plate circuit is prety normal..
Just what I needed for my vintage shack linear.
R. Measures wrote:
Jim -- If the tetrodes are being operated at roughly half of their
max screen-V rating, they are likely being run in a non-linear mode.
If they are being operated at their max. screen-V rating, and there
is a grid-terminating R, they are probably operating in Class AB1
linear service.
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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