Something else I'm finding out the hard way...
http://cgi.ebay.com/ws/eBayISAPI.dll...827584260&rd=1
Is a transmitter for a thermocouple. Looks fine, until you pull up the specs (
http://www.prelectronics.com/ ): it's actually a 16 bit ADC, which limits the output resolution significantly (nothing I didn't suspect, but always good to check!).