[AZ-Observing] Re: Astroman Site

>For anyone interested in building their own PMT photometer, the Surplus Shed
>(http://www.surplusshed.com) has a supply of IP28 photomultiplier tubes
>(http://www.surplusshed.com/pages/item/r1435.html), $10.  I bet they'd even
>cut you a deal if you bought a dozen.  It seem to remember that this tube is
>similarly numbered to one in Jeff's book, although I don't have the book
>handy to check.  Of course, if you know about tubes, you know that similar
>numbers don't mean similar performance, so check your handy PMT data book.
>
>I have purchased from Surplus Shed a couple of times and am satisfied with
>their service.
>
>Joe

Thanks Joe,

While $10 is a decent price, be aware that the 1P28 has different 
characteristics then the 1P21/931A, particularly much higher dark 
current (noisier). You might need special filters to get even close 
to standard UBV data. I recommend saving your money and look for a 
1P21.

Check:
http://www.elexs.com/7Photo.htm

The 931A is the same except the 1P21 is a selected version. They take 
the best tube and label them 1P21 and the less sensitive and noisier 
tubes 931A. The 031A is still good for most cases, however.

Also

http://usa.hamamatsu.com/hcpdf/catsandguides/PMTCAT_index.htm

If someone is interested in a 1P28, I think I have data sheets someplace.

Jeff
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                                      Jeff Hopkins
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