On Monday, July 3, 2017 at 3:01:28 AM UTC-7, frank wrote:
Hi all,
I was trying my Heathkit curve tracer on a gas discharge transient suppressor
(striking at about 200V) and I've found the following behaviour:

https://www.youtube.com/watch?v=DeKPkG5T1xc

Basicly it seems to heavily ring on the turn-off curve?

The impedance of a gas discharge, especially at low current
after a discharge event, is negative. So, it can oscillate.

Geiger and proportional counter tubes have a gas fill that includes
quench gas (CO, or methane, or somesuch) that is intended to
reduce the negative-resistance behavior. Those gasses may be
omitted from your device, or they may have been used up (depends on
how much 'test' discharge the tube has seen). So, this behavior
might not happen on an as-delivered device.