Cooke cold cathode thermocouple gauge

[John Taylor]

I recently purchased a Cooke model CC64/42 cold cathode thermocouple gauge cheaply on Ebay and wondered if anyone is familiar with it. It seems to be functional, but I would like to find some literature on it. I have already emailed Cooke Vacuum Products and they are trying to find if they still have any documentation on it. Any help would be greatly appreciated.

[DaveC]

Did you mean Cold Cathode Ionization Gage? I've never heard of a cold cathode Thermocouple gage... How does it work?

Dave Cooper

[John Taylor]

Cold Cathode Thermocouple is apparently just the name on the front. After taking the unit apart and tracing circuitry, it has two thermocouple type gauge inputs for atmosphere down to around 1 micron and then a cold cathode Penning type gauge for 10^7 torr. The two TC come into one part of the instrument and the CC goes into a seperate circuit board (with associated high voltage,etc.) The two TCs are switch selectable and feed one meter, while the CC side has a switch to select 3 different ranges. It only came with one TC connected. After purchasing another TC from Cooke, I think this will work good enough to get my homemade chamber in working shape and then I may get a CC gauge for higher vacuum (If I ever achieve a leak-free chamber with low enough outgassing, that is).

[DaveC]

John - sure....as you've discovered... there are two gage types here... the TC gage and the Cold Cathode Ionization Gage for High Vacuum.

You'll need the Penning Type Cold Cathode Gage tube for the High Vacuum work. Assuming the controller device works, you're all set.


Dave Cooper

[John Taylor]

The CC side has a 4000 volt capacitor that is breaking down, but the TC side is working fine. Thanks!

[DaveC]

John -

That shouldn't be too hard to fix. Sounds like that's the HV output filter,so almost any value of capacitance, will provide filtering. Get something will some "overhead" when you replace it - 5 to 6kV minimum.

Dave Cooper

[John Taylor]

Thanks so much for all the advice. I have plenty of room on the PC board to mount a capacitor that is much larger. I am going to replace both of the caps, and since this part of the gauge only has passive components, it should be fixed. Now, on to finishing my hi-voltage PS for the chamber...