[AMPS] Re: New G2DAF amplifier information

[Colin Lamb]

Rich said:

"Any guesses at to what would happen if a 8660/4CX1500B were used in a DAF
circuit. - with say 20mA of grid current instead of 0.06mA of grid current?"

Rich:

I have heard no one - except you - suggest using an 8660 in a DAF circuit.
Your friend, Norm, used 4CX250 tubes in a mis-understood bastard adaptation
of the original G2DAF circuit, which hung an electrolytic capacitor on the
screen grid.  It splattered badly.  It was not a G2DAF circuit.  Yet, you
use it as a basis to condemn any reasoning that is not consistent with the
world as you view it.

Tubes do not have to be used as the tube manufacturer originally intended
them to be used, and amateurs by their very nature are experimenters.  I
recently built an oscillator which used the screen as the plate.  It works
fine.  Tubes were not intended to be used that way.  It is called a Dynatron
and was designed long before I was born (which is getting rare these days).
Building any circuit - "good" or "bad" - is fine, so long as the builder
makes sure he does not unreasonably splatter.  Certain tube design
parameters must be met for the long term health of the tube.  Beyond that,
the only other question is whether the output has undesireable
characteristics such as splatter, harmonics or parasitics.  And, it is up to
the designer or builder to achieve those goals.  It would be a boring world
if all the amplifiers looked exactly the same and used exactly the same
tube.

The other day, I raised the question of increasing the screen voltage on a
grounded grid tetrode - from zero to something less than the "normal"
voltage.  Your response was "DAF circuits produce feculance".  The
"distortion"  was in your response.   I am sorry that Norm's splatter years
ago affected your outlook on life so much.

73,  Colin  K7FM


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