>On 27 Jan 2004 at 19:27, R.Measures wrote:
>
>< snip >
>
>> >Both grids need to be grounded to RF... but they don't *have* to be
>> >both connected directly to chassis.
>>
>> ** which means?
>
>I'm pretty sure Ian means that both grids need to be bypassed to
>ground, if you're going to drive the cathode.
>
>But I think Rich and Ian (and I) agree that doing a "grounded-grid"
>amplifier using one of these tetrodes is a rather silly way to build
>the amp, especially if it requires conversion from a grid-driven
>configuration!
** Good point, George. Not only would the conversion be extensive, the
2mA limit on control-grid current would seem to suggest that a 4cx350
could not be driven to 100% of it's emissive capability in g-g operation
without exceeding the 2mA limit .
>. Use normal operating voltages on the screen (bypassed
>to ground) and on the control grid (fed through an RFC) and drive the
>control grid with a suitable non-inductive resistor as a non-reactive
>load for the exciter. Published examples abound!
** And, if one end of the grid-terminating R is connected directly to
the grid, and the other end is bypassed to chassis-gnd, the grid-bias
supply may be connected directly to the cold-end of said R.
>...
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