Oscilloscope question

[Banjan73]

Hello!
Refering to my Ampeg SB-12 thread, i have done some measurements with multimeter and scope.
Well. Truth is I am no scope expert, and I have one question:
What is going on here?
I have measured the PI (cathodyne). Cathode side seems normal, but on the anode side, I have this strange graph.
Attached is pictures of both of them + combined.
Anyone keen to explain whats happening with that strange one?

[DummyLoad]

The bottom two traces are frequency doubling - You have bias shift of the cathodyne when overdriven - Add a grid stopper to the cathodyne, 270KΩ and up seems to work well, anything over 1MΩ will shave off more highs than you probably want. I typically use 330K-470KΩ for a stopper.


--Pete

[Banjan73]

Thanks!
Easy fix. I will do that.

[shooter]

DL helped me with the same problem, before n after shots;

[Banjan73]

Nice!
I'll see into that tomorrow!
(Btw... AI came up with the same conclusion. But much of that is actually based on you guys)..