• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

What is the safest method to plot characteristic curves without ruining the tubes

I am new to tubes and I have built a rig to test tubes and circuit configurations. I wish to understand the methods of doing manual curve plotting past the Plate dissipation value. I wish to do this for non published operating values, specifically for AB1 push pull applications which from what I have readn and understand, will allow temporary surges above Pd.

I have tried with a few pentodes, but I end up seeing sparkles and having oscillations on the tubes. Is it actually possible without some type of on off sequencing to average the dissipation?

Alfredo