[Crist Rigott]

Originally Posted by old_coot88

Wow, I didn't know you'd have to go all the way down to 56K. That'll be making the 12BY7 grid too positive, causing it to conduct, which you don't want. So scuttle that idea.

Maybe try the bias box further down the AGC line, as suggested earlier. This doesn't involve the 12BY7.

What is the value of the resistor between Test Pt. B and the next test point (where the bias box would connect)?

That would be R10 470K.

I removed the 56K from the 12BY7A tube.

I don't have a bias box.