Confused about PPIMV

[Bob Simpson]

I'm probably all confused, but,
I'm looking into a Skipz/LarMar type PPIMV, and
it looks like this works by varying the bias voltage.

Am I completely off base?

If this is so, how do I set the bias?

PPIMV full on, or some other value?

TIA

Bob Simpson

[Firestorm]

No, it doesn't affect the bias. Set the bias same as you would without it.

[Bob Simpson]

Thanks, Firestorm.

I'm going to have to look at that schematic more closely...

Bob

[Firestorm]

Remember that the bias supply itself is an AC ground, but not a DC ground, so only AC is affected.

[jjman]

Bias voltage is on the pot but the path to the grid does not flow dc current. No dc current so no dc voltage drop along the pot. The voltage is consistent as you turn the pot. The ac from the PI flows to the bias source. Since there is ac current flowing thru the pot there is a voltage drop throughout it's turn. Wiper decides what ac voltage point to tap for the outputs.