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Jeff, how did you arrive at 57 for the conversion factor for CPM to uSv/h for the SBM-20? I've seen other numbers such as 40 used other places...

Thanks.

-Pete

Pete,

The 0.0057 number came from the results of another Geiger project here:
http://www.cooking-hacks.com/index.php/ ... o_servants

There is also some discussion of the accuracy of this conversion factor on brohogan's excellent DIY Geiger Counter site here:
https://sites.google.com/site/diygeigercounter/software

At this time I recommend using the uSv number as a rough indicator only, as I can't personally verify the accuracy of the conversion factor - I used the best data I could find at the time I wrote the firmware. I'm hoping I can link up with some folks that have access to actual calibration standards in the future so we can verify the numbers.

Ok, I'll check those out as well. I've got a PM1621 which is reading a bit lower (difference 0.02 uSv/h) than the SBM-20 in the GC kit. The PM1621 is shielded from betas, which is probably making the difference. I'll try to hack up a beta shield for the GC kit and see what it reads then.

Nice kit, btw!

-Pete

Thanks!