>I wounder if anyone has tried to run a 4 by 15 (or 10) in the
>G2DAF configuration? It could be a problem generating enough
>g2 maybe, any ideas? If someone tried a small tube like a
>4 by 5 in G2DAF config it also would be nice to know.
In SSB-voice service, the G2DAF "Class C linear amplifier" circuit
typically produces an intermodulation distortion (IMD) level of roughly
22db below PEP. In a two-tone test, however, wherein the screen (g2) V
is constant, the IMD level is about 10 times better.
-- In voice service, the screen V in a G2DAF circuit fluctuates rapidly
and widely because screen voltage is proportional to instantaneous drive
level. . However, Eimac says that screen V needs to be well regulated to
provide minimal distortion.
-- In a grid driven amplifier, the more grid current, the more IMD. In
the G2DAF circuit, moderate grid current flows.
QRPee-preachers with high blood pressure should probably click Delete
at this point.
The '4 by 15' (8281) and its little brother, the 8171, are nice tubes.
They have much emission, warm up in under 1 second, are typically
undamaged by vhf parasites, produce low distortion, drive easily, and
make for a rather unboring amp. construction project. However, use
either in a G2DAF circuit and it becomes a rather robust SSB garbage
generator. . .
In the world of linear amplifiers, there are no free lunches.
Rich---
R. L. Measures, 805-386-3734, AG6K
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