[Amps] monitoring tube seal temps

[Larry]

 I've been following the RTTY vs. tube seal temp thread with interest. It
was mentioned that you can use the crayon to monitor the seals, but those
are one-time use. What about a circuit such as the one used in the hand-held
temperature guns (IR, I believe?). Are there available components out there
where we could make our own small-scale circuit to monitor the tube temps?
Personally, I've only seen electronic temp sensors which work up to around
150 deg C. What do you think?  Larry N1MIW