[HAM] What are the appropriate ohms values for the cathode bias

[Brad Baker]

On Jan 7, 2008 12:56 AM, Kon Zissis <kziss at ozemail.com.au> wrote:
> Geoff Williamson wrote:
> >the value of the cathode resistor is dependent on the plate voltage
> >applied to the particular valve type

(as far as I know)

Pentodes wired as pentodes have a high plate resistance.  This means
that changes in plate voltage (B+ for example) cause very little
change in plate current for a fixed grid/cathode voltage.  Look at the
curves.

The cathode bias resistance is chosen to select the value of no-signal
bias current you are comfortable with for that tube.  This current
value should be reasonably insensitive to the plate voltage.

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