Thermocouple gauge

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David Nagy
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Thermocouple gauge

Post by David Nagy »

I found this gauge (http://www.pchemlabs.com/product.asp?pid=4118) and I thought it might work for a fusor and I had a few questions about it. Firstly is it worth getting (I found this too http://www.ebay.com/itm/Hastings-DV-4D- ... 4ceff81e21). Second if I go with the conflat one what is the included baffle for?

Ps don't say I should have looked at the faqs, because I did.
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JakeJHecla
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Re: Thermocouple gauge

Post by JakeJHecla »

Please read the forum archives. There is plenty of good info on thermocouple gauges. Others have used similar units, and they seem to work sufficiently. As for the baffle, I would imagine it's there to keep out diffusion pump oil and other debris.
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Carl Willis
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Re: Thermocouple gauge

Post by Carl Willis »

For best price and function in a TC gauge, go with a brand-new Hastings DV-6M or equivalent (e.g. 6000 series from LDS or Lesker). The Varian 531 is also popular and inexpensive, but has inferior sensitivity in the micron range. The gauge tubes are $40-50 new with the typical 1/8" NPT fitting. Used tubes or new old stock tubes are sometimes available on eBay, but often these are defective or dirty. The controllers can be found all the time on eBay at affordable prices in the range of $50. Buying a used controller is typically a safe investment.

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Richard Hull
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Re: Thermocouple gauge

Post by Richard Hull »

Carl's advice is specific and great. however, a scan of the vacuum forum FAQs might have yielded.

viewtopic.php?f=25&t=3592

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
David Nagy
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Re: Thermocouple gauge

Post by David Nagy »

The conflat one in the original post has a 5 pin connector and I noticed that it is much more difficult to find this type of connector than the 9 pin type. Is the 4 pin connector varian-Agilent specific and if not could I use one of their gauges with a different make of controller?
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Carl Willis
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Re: Thermocouple gauge

Post by Carl Willis »

A TC gauge tube must be used with a controller designed for that specific type. Using a mismatched controller with a tube will result in incorrect readings at best, and possibly a damaged tube. Luckily, the common types mentioned earlier are very popular, and on any given day, eBay will have multiple offerings listed. If a controller is sold without the keyed octal socket these two tube types (and most others) use, no need to get bent out of shape about that; it's a $2 part.

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David Nagy
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Re: Thermocouple gauge

Post by David Nagy »

So basically I could use this tube with any other brand of controller as long as the connector is the same?
In some sort of crude sense, which no vulgarity, no humor, no overstatement can quite extinguish, the physicists have known sin; and this is a knowledge which they cannot lose.

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AllenWallace
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Re: Thermocouple gauge

Post by AllenWallace »

No you cannot use difference gauge controllers unless they are specifically matched to the tube type. See http://www.belljar.net/tcgauge.htm . All the tubes referenced in the article have the same octal connector, but have very different electrical specifications.

FYI, you can use a variable power supply, a current limiting resistor, DVM and an excel spread sheet graph to make an effective gauge controller.
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Carl Willis
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Re: Thermocouple gauge

Post by Carl Willis »

A DV-6M tube (or off-brand equivalent from Lesker, Duniway, LDS, etc.) will work only with the Hastings controller made specifically FOR THAT TUBE (or off-brand equivalent). Same applies to the Varian 531. The gauge faces say what tube they will work with on the front. If a controller is offered up with no identifying information, you will have to look at close-up photos and do a little bit of Googling to see if it is compatible with the tube you want to use. Definitely start by picking a tube. If this was my choice, I would go for a DV-6M brand-new and be done with it. Then wait for deals, make offers, or outright buy a compatible controller.

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Richard Hull
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Re: Thermocouple gauge

Post by Richard Hull »

Again, as noted above, the following FAQ explains this point.

viewtopic.php?f=25&t=3592

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Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Chris Bradley
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Re: Thermocouple gauge

Post by Chris Bradley »

Just MHO - I would, personally, recommend newbies find themselves a nice active gauge than worry about controllers and the like.

Here's a Pirani type for $75, but they come up cheaper than this on a semi-regular basis (in Pirani, magnetron, or full-range types):

http://www.ebay.com/itm/191020202898

I bought one just like this in the UK, seemingly barely used, and still in cal (!) for £10!
David Nagy
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Re: Thermocouple gauge

Post by David Nagy »

Ooh, that looks like a very nice gauge especially for the price. But what is that Ethernet port looking socket on the back?
In some sort of crude sense, which no vulgarity, no humor, no overstatement can quite extinguish, the physicists have known sin; and this is a knowledge which they cannot lose.

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Chris Bradley
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Re: Thermocouple gauge

Post by Chris Bradley »

It is a standard RJ45 connector, so you can find yourself a regular network cable and cut it to access pin-outs. Do a search here and I have posted the pin-out config for this type of gauge.

It's one reason why these things make so much sense - you can find RJ45 connectors thrown away in the back of most IT centres, whereas the cables for many older type gauges are often the most expensive thing to find.
David Nagy
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Re: Thermocouple gauge

Post by David Nagy »

so could you have it display data on something like a raspberry pi?
In some sort of crude sense, which no vulgarity, no humor, no overstatement can quite extinguish, the physicists have known sin; and this is a knowledge which they cannot lose.

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Chris Bradley
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Re: Thermocouple gauge

Post by Chris Bradley »

You get a voltage output which is the pressure reading. Any way you can convert a voltage signal to a reading is fine. I just use a voltmeter, and get used to what that translates to in pressure.
David Nagy
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Re: Thermocouple gauge

Post by David Nagy »

i see
In some sort of crude sense, which no vulgarity, no humor, no overstatement can quite extinguish, the physicists have known sin; and this is a knowledge which they cannot lose.

J. Robert Oppenheimer
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