#136
Posted: Fri Apr 08, 2011 10:41 am
Ok, well that seems to be the case, got the formulas working and see he shows this circ as a CF augmented plate follower so I've borrowed his drawing and put our values in for 20x gain.
The 95V and 120V should have ?? by them, what will happen there Nick?
These take no account of losses in the cathode follower and in his formula terminology give,
R 71274
a 20.75
gain 20.38
Ratio 1219
rp 50000
mu 100
Zo (plate follower only) 55k46
Mike, I looked at the first stage again and think AG used the high plate load as he had a low HT and didn't need a lot of current. This gives a gain of 55, and distortion should be low guessing from the data sheet. It also keeps the coupled voltage lowish and will suit my heaters raised 40V.
So I'll put in on a board and see if it works. My maths are dodgy and Nick's idea for the IV is untested so it should be interesting!
The 95V and 120V should have ?? by them, what will happen there Nick?
These take no account of losses in the cathode follower and in his formula terminology give,
R 71274
a 20.75
gain 20.38
Ratio 1219
rp 50000
mu 100
Zo (plate follower only) 55k46
Mike, I looked at the first stage again and think AG used the high plate load as he had a low HT and didn't need a lot of current. This gives a gain of 55, and distortion should be low guessing from the data sheet. It also keeps the coupled voltage lowish and will suit my heaters raised 40V.
So I'll put in on a board and see if it works. My maths are dodgy and Nick's idea for the IV is untested so it should be interesting!