Rich, you are the master of the red herring.
You argue that the G2DAF circuit cannot be linear because it draws grid
current. Class AB1 does not draw grid currrent. Class AB2 and B is allowed
to draw grid current. Most amateur linear amplifiers are running class B
and do draw grid current.
Let us examine tube data for the 4-125A tube in a grounded cathode circuit:
Class AB2
Plate volts = 2000; Screen volts = 350
Screen current = 3 ma
Grid current = 7 ma
Source is Single Sideband for the Radio Amateur, Published by ARRL in 1965,
page 252.
This information is only cited to show that tubes can run grid current and
still be linear. It is not proof that the G2DAF circuit works. The data
also suggests that the 4-125A series of tubes would be ideal to test the
G2DAF circuitry - especially since the original tube used by G2DAF was
similar to the 4-125A.
The 4CX250 series of tubes would not be a good candidate for the G2DAF
circuitry. Bill Orr's Radio Handbook, 18th Edition, 1970 at page 720 says
that "a high perveance tetrode... cannot be used in conventional zero-bias,
class-B grounded-grid circuitry, since the element geometry within the tube
leads to abnormally high values of grid current and possible destructive
values of grid dissipation". That same reasoning applies to use of the
4CX250 series in G2DAF circuitry.
Finally, I have come up with "Rich's Rules of Engagement"
1. Rich is always right!
2. Facts that interfere with Rich's beliefs should be ignored or
rejected!
3. Conclusions that conflict with Rich's beliefs should be distorted!
4. Logical thought will be rejected unless it is consistent with Rich's
beliefs!
5. Those who question Rich's beliefs are cultists and should be
ridiculed!
6. Rich is always right!
Colin K7FM
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