I’ve been running the GCM-500+ continuously 24/7 for about 10 months now. It was set up to measure ambient radiation and is logging datapoints every 2 minutes. I’ve noticed that for the first 7 months or so, I never saw any reading above 50 CPM. Now after 8 months I’m seeing 50CPM+ readings two or three times a day.
I’m wondering how frequently these things needs to be recalibrated?