Tube Theory part 4

Here is tube theory part 4.

[@vinylhound43]

This is a fantastic series! Thank you so much for sharing your knowledge.

[@MrStratMax]

Thanks now I understand the way caps works in a circuit

[@dennis525371]

Thanks, I'm glad it helped you.

[@Ragitysdad]

Great Job Dennis. Thanks again.

[@eyesore2004]

Dennis, on your contact bias diagram, won't that huge resistor between the control grid and ground raise the control grid to be quite positive with respect to the cathode? You state it will keep the grid negative, I don't understand. Thanks for all your videos!!

[@ranuts2]

More good stuff for me, thanks....

[@ianhames2465]

Thank you for uploading your knowledge of vacuum tube theories, I have learned a lot from your videos. I have a problem biasing a 12ax7, and I would like your opinion on what may be happening. I may have a dead tube by now, which I am tending to think may be the case. Basically, I have a 170V B+ and I chose 2.5mA current. This gave Rp = 66K Ohm. I have Rk = 1K2 and Ck = 25uF, Rg = 100K Ohm . On power up, I get 162V at the plate, 0V at the Kathode and 0V at the grid.
Basically, I am getting 8V across 66K Ohm, giving 121uA.
Can you decypher where I am at with this lot? lol, sorry.

[@dennis525371]

+semahnai Try reducing the cathode resistor to 400 ohms and see if that helps.

[@ianhames2465]

I will give it a try, thanks for your response.