J305 conversion factor

It is either 0.00332 or 0.00812. I have no idea which, or even if they are correct. I have been using 0.00812 for the J305, but I'm unsure if this is correct. I have never found a solid answer to this, nor have I ever found an actual proper data sheet for this tube, only a couple of tables on aliexpress/amazon/ebay that state their sensitivity, and I have found differing numbers for the same tube. I also think there has been more than one iteration of the J305 as some measure 88mm and some measure more. I also have a J305 that is sensitive to light, and one that isn't, and I have one that looks like a copy of the J305 with no markings on the tube. It is these discrepancies that puts me off using the J305.

There is some discussion about the conversion factor on Steadramon's ESPGeiger github page here:  https://github.com/steadramon/ESPGeiger/discussions/14

If I had a more solid answer, I' d be happy to help, but I've been struggling with this myself.

I asked ChatGPT if it could find the conversion factor. It says the recommended number is 0.00332 for background monitoring. The conversation is in the PDF attached.