> From: Rich Measures <measures@vc.net>
To: <amps@contesting.com>
> Date: Tue, 22 Jul 97 12:37:06 +0000
> This WAS a discussion about grid current in grid-driven linear
> amplifiers. The 8877 is not practicable in grid-driven linear amplifier
> service. Apples are not oranges.
That's another interesting statement!
Are you saying triodes can't be used in grid driven AB2 systems?
What is the technical reason triodes can not be used in grid driven
applications?
> >Saying grid current always produces more IMD is a good example of
> >distortion......... a distortion of fact.
> >
> I agree that this statement is a distortion of fact, Mr. Rauch.
> - In a cathode-driven (Class AB2 G-G) config., grid current is essential
> in order to be able to utilize the full emissive capability of the
> cathode. However, in a grid-driven config., more grid current results in
> more non-linearity. If this were not the case, we would see many tubes
> rated for Class AB2 grid-driven linear amplifier service.
Why does a grid driven PA need grid current? I don't understand that!
So far as I know, the only difference between grid driven and
cathode driven is in the system's feedback. In a grounded grid PA the
output is in series with the input, and this applies negative
feedback determined by the ratio of driving impedance to anode load
impedance.
In a grid driven PA there is no "naturally occurring" negative
feedback.
None of this seems to restrict the class of operation.
What is the technical reason for your claims?
73, Tom W8JI
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