Cat Follow & Gain

[trem]

Sorry if I have this wrong but...
My understanding of a cathode follower is that the output at the Cat is in phase with the Grid, and has "no" gain when compared to the gain of the output at the Anode.
Just for example.....
An AX7 may have Gain of 70, but Gain at the Cathode is about 1 or less.

If I have that correct (more or less), what happens with a Cathodyne Phase Inverter.?
Wouldn't the amplitude of the out of phase signal at the Anode, be much greater than the in phase signal at the Cathode.?
Doesn't that cause a problem.?
Thank You

[R.G.]

A cathode follower has a voltage gain which is less than one. Just how much less is in an equation back in the RDH that I can look up, but say it's 0.9 to 0.95, depending on tube, power supply, resistances and phase of the moon.

If the CF forces a voltage "gain" of 0.9 to a resistor to ground on the cathode, then the current that flows is the voltage divided by the cathode resistor.

Notice that in a tube, essentially zero current goes into or out of the grid in most cases. So the current flowing in a triode in the plate is equal to the current flowing in the cathode.

If you put a resistor from B+ that's the same size as the cathode resistor, and we know the same signal currents flow through the two equal resistors, then the signal voltages must be equal to within the tolerances of the resistances. So no, the gain to the plate is not much greater than the cathode. It depends on the relative sizes of the (unbypassed part of) the cathode resistor and the plate resistor.

[trem]

OK....that's right.
Thanks RG.
And "we" usually (always.?) see a Cat resistor that is equal to the Plate resistor in a CF.....
Thanks Again

My questions always seem so stupid after you guys answer them...

[Jazz P Bass]

A 'stupid question' is always much prefered to a 'stupid answer'.

[Enzo]

Oh, I remember a stupid answer. I said it myself. I think it was something like
: "I do."

[Chuck H]

A 'stupid question' is always much prefered to a 'stupid answer'.

Hey! I resemble that remark!