[Amps] GG amplifier input impedance

[Bill Fuqua]

Some of you are getting confused between the difference of the
the impedance between the elements of the TUBE and the impedance of the 
complete
circuit.  He is referring to the grid to cathode impedance of the TUBE.

    The cathode to ground impedance of a grounded grid amplifier involves
the cathode grid and the plate.  This is quite different than the grid 
cathode impedance
of the TUBE.

73
Bill wa4lav



At 03:09 PM 8/26/2009 -0400, you wrote:
> >    Grid to Cathode impedance of a tube
> > is the grid to cathode voltage divided by the
> > grid current!!!
>
>    I wouldn't be so quick to say that.  Nothing is that simple.
>    The load on a grounded grid amplifier is seen by the amplifier's driver.
>   (I assume as long as the GG amplifier is drawing plate current)
>A good percentage of the driving power winds up in the grounded grid
>amplifier's load.
>    You drive the cathode, the cathode is connected (through plate
>current) to the plate of the tube that is connected through matching
>networks etc. to the load.
>--
>    Ron KA4INM
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