dynatron oscillation

The tetrode wasn't the only tube which could generate dynatron oscillations.

The term "dynatron" came to be applied to all negative resistance oscillations in vacuum tubes; for example the split-anode magnetron was said to work by "dynatron oscillation".

In addition, since dynatron oscillations were a source of instability in amplifiers, the tetrode's main application, tube manufacturers began applying a graphite coating to the plate which virtually eliminated secondary emission.