For 650 deg C you need a J or K thermocouple. A Fluke 51 runs $200, a Extech EA10 is $110, a Extech 421501 is $100.

We have a cheapie at $25... make sure you order the C version... the probe it comes with is junk but should work a little while before it melts. You'll need a high temp probe. It goes to 720 degC.

http://www.davis.com/Default.aspx?pa...mometer*2084@@

I'm the Quality Manager for Davis Instruments and we just sold off the sales division or I would get you a really good deal....