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Re: Gauges

Posted By: SVP Neon Equipment
Date: Monday, 1 April 2013, at 7:53 a.m.

In Response To: Re: Gauges (Romarrk)

> Well, that was my error at first time.
> Hastings tubes won't work with DC drive. I
> already admitted it. Older 531 style and the
> one I use will work well.

Your mistake is dully noted. But it's not the first one, and I'm sure it won't be the last.

> All this fancy wording actually just relies
> to cold junction/case temperature
> compensation. May be relevant when you need
> to make instrumentation guaranteed over full
> -55/+125C mil range, but not for neon shop
> desktop! Even old style tube with single
> thermocouple will work very well here once
> calibrated for a single time. Until it start
> drifting because of getting dirty, with
> which all compensations won't help anyway.
> This single thermocouple measures temp
> DIFFERENCE INSIDE sealed tube envelope,
> which depends on gas density/type, and
> heater power applied. And the only critical
> parameters that may in principle slightly
> drift with external temp are gas constants
> (not much for neon shop range) and platinum
> heater resistance (not much too). So you
> will get 1 micron reading instead of may be
> 1.1 Any relevant for neon work? And
> mentioning atmospheric humidity is just pure
> BS here. Until we are not sending it to Mars
> ;-) This is not a transmission tube. No
> serious heating at all, may be a few
> milliwatts. Sorry Mark.

If you go back and review the thread you should quickly notice that I am not the one using all the "fancy wording". I don't need to. Those who are hopelessly trying to prove something and do not have anything better to do are the ones who do.

Well, you know what they say about opinions. You are completely ignoring the electronics that drive everything, including, but not least of which, is the gauge tube. But what do I know? I know that NASA must choose Hastings vacuum instruments for a reason.

But there are some key things you mentioned that should be addressed. The first is, "calibrated for a single time." As in, calibrated every time you want to use it. (Didn't I already cover that? Oh, yes I did). You can argue it all you want, but that's the reality of it. If you don't, the "instrument" (and I use the term loosely) is not giving a true reading. The second is, "Until it start drifting because of getting dirty". That begs the question, Why would it get dirty? Unless you are not using a stopcock/valve to isolate it from the system while processing, etc. Even so, if you know what you are doing, many times the gauge tube may be cleaned if the contamination is minor.

Sorry for what? So far you haven't proven anything to me other than you know how to look things up on the internet and try to talk a good game (actually, not even that good.)

> Quick closure of stopcock will reveal it. In
> my experience with professional pumping
> station with secondary pump and all that
> fancy stuff all reasonable tube defects
> still notably dropped absolute vacuum.

I was not talking about a big hole. I was referring to a pin hole that could easily be masked by strong pumps.

In your "experience" you have admitted that your "professional pumping station" is set up in your kitchen and you are having a hard time deciding whether or not to use mercury because you are afraid you may contaminate your kitchen with mercury. Again, if you knew what you were doing as much as you *imply* you do, you wouldn't be worried about it because you would know how to handle it. Yeah, that's what I call "experience"! I seriously doubt you have any long-term hands-on experience in the real world of tube processing, much less using the equipment being discussed. In fact, (to me at least) your comments prove just the opposite.

With that I will close. Don't expect any further replies from me. What you have proven does not merit any.

PS: Nice touch trying to stick in the broken Russian English again ;-) Absolutely hilarious!!!

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