Why do vacuum tubes flip a signal out-of-phase?

[frwdrik]

Hi there!

Got a little question:

Why is the signal at the anode out-of-phase with the signal at the grid?
I have read a bit about it, and it seems to me that while the grid is getting more positive, it'll allow more electrons to flow towards the anode. Shouldn't this mean that the signal at the anode is in phase with the grid?

Thanks,
frwdrik

[Jerry Glass]

As the grid goes more positive, the current increases through the tube causing a greater voltage drop across the plate resistor which makes the voltage at the plate go less positive.

[frwdrik]

Thanks, Jerry!

The things I've read about tubes sound familiar with what you said, though I wish it was stated as clearly as your answer!

Thanks,
frwdrik