Greetings from Poland!

Hi Pawel,

Welcome to radmon.org! Nice job getting your counter setup and submitting. It looks to be working well.

Something to be aware of with your counter is the tube may be light sensitive. It looks like a J305. Some J305, M4011 and other tubes have been reported to be sensitive to sunlight/daylight/UV. It would be good to cover the tube in some kind of opaque sleeve to block any light from getting to it. Any kind of non-metallic material should do the job. Black electrical tape, dense black card wrapped around, some heat shrink sleeving, anything really that will block light but not radiation. A plastic PVC pipe would also work, but in my experience using it, it does lower the CPM ever so slightly. Like 2 or 3 percent or so. I would personally use black electrical tape simply as I have some to hand. That said, yours may not be light sensitive, but after playing about with a light sensitive tube I think I would cover all glass tubes from light just to be certain.

I did a post on my light sensitive tube that you can see here:  https://radmon.org/index.php/forum/geiger-muller-tubes/1298-j305-gm-tube-light-sensitivity-to-uv  

I currently have my CAJOE with J305 sat in my window as part of an experiment with sunlight/daylight. It reacts well to the sun. I need to do a proper write up on it, but the results (so far) of it being in daylight are here if you are interested:  https://radmon.org/index.php?option=com_content&view=article&id=30&station=SimoTester3