[Amps] monitoring tube seal temps

[Radio WC6W]

Hi Larry,
  There are a couple manufacturers (names escape from my moldy old mind this afternoon) making complete sensors, with lenses and signal processing, in a transistor sized case covering up to 300 degrees C.  I believe that they cost about $30 ea. in small quantity.

  A homebrew version might be cobbled together by cutting the top off an old germanium transistor, covering it with a piece of opaque trash can plastic, and using a small mylar conical concentrator in lieu of a lens.  A temperature sensor IC, or a second transistor of the same type, could provide the ambient reference.  A small PIC or other uP, with an integral A/D converter & a PWM output, could process the somewhat nonlinear (4th power function!) raw signals to drive a meter.  Calibrate it against a mercury thermometer in the kitchen oven and viola!

  The latter approach could share the processing circuitry with multiple sensors, for multiple tubes, or multiple location sensing.

73 & Good afternoon,
  Marv WC6W 

http://wc6w.50webs.com/


--- On Sun, 7/5/09, Larry <n1miw at cox.net> wrote:

> From: Larry <n1miw at cox.net>
> Subject: [Amps] monitoring tube seal temps
> To: Amps at contesting.com
> Date: Sunday, July 5, 2009, 6:26 AM
>  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
>