Hi Rick,

I didn’t notice this in my tests so it might be a particular case. Ignoring the first readings is not the best option, we would need to see the root cause of the spike instead. Ignoring would waste precious data, and we’ll never know how to set a “first interval” value. 1 minute? 10minute? Not reliable as if there is a problem it can happen at any time.

Looking at the chart I see the time axis is continuous, where did the power off occur?

On older firmwares there was a default duty cycle set for the inverter. At power up this could have produced higher voltages, potentially resulting in excessive counts on the geiger tube, however I see you run 110 already, where the duty cycle starts at an absolute minimum and is brought up to the required value, as controlled by the internal regulator.

Another cause might be the so-called “compensation capacitor” that might need to be replaced on your unit. This component is responsible for controlling any unwanted oscillations taking place over the tube. But I see no reason why this capacitor would fail, so this is not a real explanation either.

Power failures might still induce voltage spikes of various kinds. Can you run a few power off/on cycles and see if this is happening on a consistent basis? I suspect not.

But let me know.

Thanks,
Radu