| Products > Test Equipment |
| Does old test equipment really ever become truly obsolete? |
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| 2N3055:
--- Quote from: pqass on May 25, 2024, 01:36:35 pm --- --- Quote from: nctnico on May 25, 2024, 10:18:01 am --- --- Quote from: David Hess on May 25, 2024, 12:00:08 am ---I have been looking for a bench multimeter that can calculate standard deviation, but it has to be over a specific period of time or a specific number of samples to be useful. Right now I do it manually on my calculator. --- End quote --- I'm looking at getting a UNI-T UT8805E bench DMM which can do that. It supports measuring a specific number of samples and calculating the standard deviation. But I'm sure modern day bench DMMs from Tektronix and Keysight have a similar feature as Uni-t must have copied the idea from somewhere. --- End quote --- The HP 3456A from 1981 can do this. It can be had for about $250 on eBay and has a lovely LED display. Enter the number of samples, delay between samples, and it will produce min, max, mean, and variance after a single trigger button press. You'll have to √variance yourself for std dev though. --- End quote --- That function is also available on Rigol DM3068 and a slighty simpler version on DM3058. Also on Siglent SDM3055/3065. You can also set various triggering options, etc. |
| Alex Nikitin:
--- Quote from: David Hess on May 25, 2024, 12:00:08 am ---I have been looking for a bench multimeter that can calculate standard deviation, but it has to be over a specific period of time or a specific number of samples to be useful. Right now I do it manually on my calculator. --- End quote --- I do have the HP3456A in my lab, however my new HIOKI DM7275 7.5 digit DC voltmeter can do it as well, I can set a manual/external trigger, a delay and a number of samples per a trigger event, and the statistics display gives max/min/av/p-p/stdev. Cheers Alex |
| pdenisowski:
--- Quote from: David Hess on May 25, 2024, 12:00:08 am ---I have been looking for a bench multimeter that can calculate standard deviation, but it has to be over a specific period of time or a specific number of samples to be useful. --- End quote --- Our HMC8012 bench multimeter can do this - calculates standard deviation based on a user-defined number of samples (up to 50,000) :) https://www.rohde-schwarz.com/us/products/test-and-measurement/rs-essentials-meters-and-analyzers/rs-hmc8012-digital-multimeter_63493-44315.html |
| S57UUU:
If you need to test modern stuff like 5G or something, using old instruments would make it very hard work if not impossible. New instruments have built in "personalities" that enable "one button press" measurements to test compliance with modern standards. But I don't need that for my ham radio and radio astronomy hobbies. For that, my stack of old instruments from the 80's serves me very well. They are "just enough digital": they do calibration and error corrections, and can be computer controlled via HP-IB, but no windows virus gardens and similar. For example, some five years ago I bought a HP8593E with the 26GHz option for 1200 euros. I don't think there is a modern alternative that would fit that budget. I do have a nanoVNA and a SAA-2, also a tiny SA ultra, these are great when out in the field. But when at home, I prefer to use my HP8714ES and HP8720A, the user interface is just soooo much friendlier. My HP8663 opt 103 is bulky and heavy, bought it for 600 euros. Even today, it is still among the cleanest signal generators. Also have an HP8673 up to 26GHz, don't know of any cheap modern alternative. I cobbled together a HP3048 system with HP11848 and HP11729. It is run by a DOS/ISA computer, is slow and bulky, but it measures up to 18GHz and gives great results. My HP8970 uses totally obsolete detector based technology, but measures noise figures very well, on par with modern equipment. Admittedly, I am an old fart, I used these boxes as a young professional in the 80's, so they grew close to my heart. But I do believe they can still be very useful today. Service manuals, schematics and even EPROM firmware files for most of them are available on the web, also the through hole components make them easy to repair (for now, I mostly had to replace some electrolytic caps). Some of my instruments were old stuff even in the 80's, like the HP3400, which I call a "true-true-RMS meter", and I still find it useful. As far as scopes go, I just bought a rigol 814 and a set of "pc bite" self supporting probes, it is great for debugging serial stuff. But when just needing to see some signals, for example in the audio range, I still sometimes fire up my tek 2232 (and 2467 until the battery went bad and it forgot it's calibrations). |
| coppercone2:
test equipment often evolves to 1) make tests run faster, because more tests of more devices is ALWAYS the easiest route for a test lab to take to show 'improvement' in a way that non technical people understand and will not question (don't want your budget to get interrogated, don't want to teach old dogs and some how gophers where there should be dogs new tricks). It is also a measuring contest between competitors, because volume means quality. 2) allow for less trained personnel to run tests (lower salary, allows for more workers doing tests, decreases cost of hated QC and R&D departments, easier to hire (they like to get irrelevant professions and pay little) 3) less chance of error (harder for sloppy work to screw up, ties into 1&2. i.e. irrelevant degrees & uninterested people slamming buttons) 4) decrease load on analysis (that is, have the company "approve" some calculated number so the buyer can say "well _____ says that this method of data analysis is the "standard" for this industry)..... (again, it might mean that a clueless TE company is making decisions about something it knows nothing about that govern standards of another unrelated industry... they often don't know what is best for the customer but the customer wants them to back them up as much as possible for liability reasons, and it sounds good. like yeah we are on the same page as ______) These are IMO the driving factor for MANY equipment decisions. Its often not engineered to give you that much more capability because IMPLEMENTING new more precise and interesting stuff for the companies buying the TE is HARD compared to doing more of the same. I am sure there are engineers at TE manufacturers that wanna raise the bar of precision and deep thought, but they do end up making (alot of) stuff to be appealing towards customers. Business people hate buying equipment, these listed factors are a huge 'no argument' selling point that does not require visionaries to see the potential. Then of course sales will tell the TE designer that "this is the selling point now". But if it actually helps improve things, instead of just being empty calories, I am not sure about that. Too much data is more and more common because they feel 'data rich' and 'confident'. It could also be seen as over weight with lots of ru(b)bles in the pocket |
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