Output Z

[lowell]

Could someone be so kind as to help me calculate two output impedances?

1:
A capacitively coupled 6V6 with Va of 150v and 5k Ra and 250 Rk.

2:
A IRF820 in follower config. Vd of 320 and Rs 100k.

THANKS!!

[Mike Sulzer]

Could someone be so kind as to help me calculate two output impedances?

1:
A capacitively coupled 6V6 with Va of 150v and 5k Ra and 250 Rk.

2:
A IRF820 in follower config. Vd of 320 and Rs 100k.

THANKS!!

1:
Real approximately, 5K. I expect the plate impedance of the tube to be several times that, so ignore it.

2:
The forward transconductance is 1.5 S, according to some data sheet from the web, at something over an ampere, I believe. So .66 ohms at that current. I bet it is higher at the current you will run, but I did not find enough info.