>
>hi all,
>
>> 'Super cathode driven' applies to a tetrode where the
>> screen is grounded and the grid is operated at 0 RF-V
>> with respect to the cathode. Thus, there is never any
>> grid current in a super cathode driven amplifier
>> circuit.
>
>not necessarily. 'super cathode driven' is where a fraction, call it "k"
>of the driving potential applied to the cathode is applied to the grid
>as well, thus providing some negative feedback. if "k" is zero, we have
>normal cathode-driven operation (i.e. the grid doesn't move, the cathode goes
>up and down.) if "k" is unity, the grid chases the cathode up and
>down, tracking it exactly.
If K is unity, the grid is tied to the cathode. Tying the grid to the
cathode seems unlikely to produce amplification unless a (grounded)
screen is present.
> it is *definitely* true, however, that the
>most reasonable thing to do when using this mode with a
>tetrode is to make "k" equal to unity, i.e. the grid and cathode are
>at the same rf potential, and therefore there is no chance of the
>control grid drawing any current (assuming the tube is biased at a
>reasonable operating point.)
If the grid and cathode are at the same potential, the grid can not draw
current even if the tube is biased at an UNreasonable operating point.
>just picking nits....
>
>73,
>
>George T. Daughters, K6GT
Rich---
R. L. Measures, 805-386-3734, AG6K
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