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Slideshow: Long-Life Equipment
12/17/2013

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A megohmmeter manufactured by IET labs still uses a vacuum tube. 'We'll manufacture these meters for as long as we can get the tubes,' said electrical engineer Joel Goldberg.
A megohmmeter manufactured by IET labs still uses a vacuum tube. "We'll manufacture these meters for as long as we can get the tubes," said electrical engineer Joel Goldberg.

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David Ashton
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Fascinating stuff.....
David Ashton   12/17/2013 4:04:41 PM
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....Martin, but your photos from slides 5 and 6 have got swapped, they don't match the captions.  

I'd love to have even some of the stuff in their museum.  It looks better built than a lot of the stuff you get these days....

MeasurementBlues
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Re: Fascinating stuff.....
MeasurementBlues   12/17/2013 5:03:51 PM
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Thanks David. It's fixed now. What's impressive is the care that goes into these old instruments even though they are still manufactured. Follow the link in the first paragraph and see the rest of the story.

MeasurementBlues
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Re: Fascinating stuff.....
MeasurementBlues   12/17/2013 5:04:59 PM
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David, I was particularly surprised at the tube version of the tach, in that they can still get the tubes. In this company, it seems as though ifthey couldn;t get the parts, they'd make them.

David Ashton
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Re: Fascinating stuff.....
David Ashton   12/17/2013 7:02:04 PM
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Hi Martin...I can understand tubes in a megohmmeter, for the high impedance, but you'd think they'd be able to transitorise a Tach.    Then again, if it works (and you can still get the tubes) don't fix it....

MeasurementBlues
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Re: Fascinating stuff.....
MeasurementBlues   12/17/2013 7:47:57 PM
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David,


That's the thing about test equipment. Not only does "If it works, don't fix it" apply, but most people buying these already have them. They know what to expect from the equipment. Even if you can make it better, you don't. Well, not always. Why? Because having something better might reveal faults that would otherwise go undetected. Igorance is bliss.

Etmax
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Re: Fascinating stuff.....
Etmax   12/20/2013 8:45:19 PM
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There's a few Russian companies that manufacture vacuum tubes, some even make them to order. A friend of mine wanted to make a valve amplifier that actually produced high quality audio and designed a valve that met hit criteria. He's using one of these companies to make it :-)

MeasurementBlues
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Re: Fascinating stuff.....
MeasurementBlues   12/22/2013 12:36:59 AM
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@Etmax, thetubestore.com lists tube manufacturers.

prabhakar_deosthali
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What about the staff?
prabhakar_deosthali   12/18/2013 6:37:05 AM
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One thing surprises me is that how they are able to maintain their staff or train their new staff. As the fresh grads coming out of colleges wouldn't 'have seen something called Vacuum tube, they need to have some retrograde training on basics of electronics and components of the older generation.

zeeglen
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Re: What about the staff?
zeeglen   12/18/2013 9:13:32 AM
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On the top of my cube wall is perched a 6201 / 12AT7 dual triode for all the younger staff to see.  They may not know how it works, but they can now say they have actually seen a real vacuum tube (valve).

The old test equipment just keeps on going - and going - and going.  No flash memory to degrade and guarantee failure in just a few years.

MeasurementBlues
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Re: What about the staff?
MeasurementBlues   12/18/2013 4:02:18 PM
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@zeeglen wrote "No flash memory to degrade and guarantee failure in just a few years."

But how well does the old equipment hold it's calibration? I bet it drifts early and often.

MeasurementBlues
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Re: What about the staff?
MeasurementBlues   12/18/2013 4:16:11 PM
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@prabhakar_deosthali, that may be the one thing that puts a company like IET out of business. Everyione who works there is an expert at his or her job and has been doing it for many years. When they reture, who will replace them?

There's another issue and that is because these people have a unique skill that's not necessarily transferable to other jobs. Thus, they have a job for life as long as the company stays in business, but there's little room for advancement or for changing jobs.

przem
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old equipment
przem   12/18/2013 2:38:36 PM
When I was a TA in charge of the physics lab, we had a closet with old but working equipment, including some voltmeters that were made in the thirties. What really impressed me though is the note inside stating that it was made to a design by Lord Kelvin from 1870s. That's longevity.

Etmax
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Re: old equipment
Etmax   12/22/2013 4:38:33 AM
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I worked on a lot of old equipment, and it all had the same problem, it was unreliable, drifted like crazy and NEDED calibration to attain what are now considered mediocre specs. These days any voltmeter from a company like Fluke etc. that is ~1% accurate usually doesn't need calibration, we just do it because the standards say so. Get to 0.1% and you occassionally need calibration. Things sure have improved

MeasurementBlues
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Re: old equipment
MeasurementBlues   12/23/2013 12:51:31 PM
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@Etmax,

Yes, digital calibration and adjustment has certainly cut down on drift. There will always be some. that and the quality requirements keep calibration technicians employed.

David Ashton
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Indestructible test gear
David Ashton   12/19/2013 10:46:51 PM
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The old HP test equipment was pretty long lived as well, there are some legendary stories about it.  My favourite is here

http://users.monash.edu.au/~ralphk/hp-counter.html

I've posted this before so apologies to those who may have seen it before.

 

JeffL_2
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Not a CRT?
JeffL_2   12/21/2013 10:07:27 PM
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The caption says there's a CRT in the upper right corner of the capacitance bridge panel in image 13, but is it really? I have a hunch it's just a little screen over the top of a 6E5 "magic eye" tube but I could be wrong, those were quite common on test equipment of that vintage and function. Basically it's a replacement for a meter when all you needed was an indication of an analog null condition, like showing that the bridge was properly in balance.

MeasurementBlues
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Re: Not a CRT?
MeasurementBlues   12/22/2013 12:32:36 AM
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@Jeffl_2

As I recall, it was in fact a CRT.

>The caption says there's a CRT in the upper right corner of the capacitance bridge panel in image 13, but is it really?

DarkMatter0
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Learning from old designs
DarkMatter0   12/23/2013 1:49:37 PM
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Check out Dave Jones' excellent tear-down and design analysis of a Fluke 5450A Resistance Calibrator:

http://www.eevblog.com/2013/11/06/eevblog-544-fluke-5450a-resistance-calibrator-teardown/

Also check out his most-excellent rant in reply to a wet-behind-the-ears viewer who commented that there was nothing to be learned from examining "old" equipment designs:

http://www.eevblog.com/2013/11/07/eevblog-545-vintage-design-rant/

 

 

MeasurementBlues
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Re: Learning from old designs
MeasurementBlues   12/23/2013 2:08:39 PM
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Dave's videos are fun to watch. Mine are somethat leff frequency and more subdued. That reminds me, I do have a product review to do. Mayne after the holidays.

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