6SN7 input stage unexpected frequency response

[jan.didden]

Gerrit, do you know that most scopes have an output (often just a 'hook' on the frontpanel) for this? Just connect your probe to it and adjust the probe trimmer for best square wave.
It is something that should be done as a matter of routine everytime you use an unknown probe. It takes less than a minute.

Jan

 

[gerrittube]

Hi Jan,

Yes I know, but I’m not using a scope right now. I’m using a Steinberg UR242 with software do do most measurements and I have a Velleman all-in-one USB device.,

Regards, Gerrit

 

[jan.didden]

Ahh, OK. The Velleman's I know have a function gen that can output a square wave.

Jan

 

[gerrittube]

Yes, it’s OK now.

Regards, Gerrit