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This situation (lack of schematics) is powering the open source test instrument surge. Test instruments are an interesting space in the technology center mostl

This situation (lack of schematics) is powering the open source test instrument surge. Test instruments are an interesting space in the technology center mostly because they are never "obsolete." If they are operating to their original specifications and tolerances, they do the job just as well in 2020 as they did in 1960. As a result, test equipment can really hold its value well. I recently paid about $700 to have my HP Spectrum Analyzer from the early 90's[1] calibrated. I bought the instrument for $1,100 at auction, it's working range is 9kHz to 12GHz. So for $1,800 I have an instrument that, if I were to buy the current generation model, would cost me nearly $18,000 or 10x that price. Even a "cheap" Rigol that only goes to 6.5GHz would cost $10,000. So what to do when your sales are "one and done" ? It is a hard problem from a business model perspective. [1] EDIT: Turns out it is only 30+ years old, not 50+. Its an HP8596E "portable" (weighs quite a bit :-).

wbl 7y ago
Make instruments and sell them like furniture makers, carpenters, most kinds of law (how many wills do you need?) etc
- ChuckMcM 7y ago
  Sort of a 'make on demand' model. It might work. These days it is hard to find parts that don't get end-of-lifed after 5 years, so you're re-doing schematics and thus your instrument's PCB. You could perhaps make a modular structure such that the instrument was constructed from modules but I'm not sure how well that would work. The open source trend is to put the instrument in its box and connect via USB to a computer that provides the UX. That works but has the issue of computer operating system compatibility. I've got a USB scope in my junk drawer that has a UI that only works on Windows 98. Not too useful these days, and the company is out of business. The instrument control protocol standards help here.
  - blattimwind 7y ago
    To some extent standardized assemblies have been used for a very long time. HP System 2 (the cute 1/3 rack units) is from the 60s, System 3 from the late 70s (I think), though the actually walked back on that one and later replaced the standardized cast aluminium parts with unit-specific sheet metal bending (3478A and others). Later they re-used the display/input modules, both HP and Keithley did this for a lot of their later DMMs and SMUs.
  - colonwqbang 7y ago
    I assume that the program that only ran on Win 98 is not open source. If it was, chances are someone would have ported it to Linux by now.
    - ChuckMcM 7y ago
      You would be correct. Of course it is just a USB 2.1 box and enumerates as a HID device and a bulk data endpoint so presumably spending some time with a USB protocol analyzer and running it through its paces would illuminate some aspects of its operation. This is why its still in my junk box and not in an ewaste skip somewhere :-)
      - simcop2387 7y ago
        What model is it? There's a non-zero chance that someone has done that work already and made it work via sigrok, https://sigrok.org/wiki/Supported_hardware#Oscilloscopes https://sigrok.org/wiki/Supported_hardware#Oscilloscopes
  - lb1lf 7y ago
    -Perhaps a stupid question, but wouldn't that UI live and thrive inside a Win98 VM? (I am cursed by the instrumentation gods - I have to keep all sorts of late-paleolithic configuration software running to support the ditto hardware we still rely on for specific tasks in our service department. I've found that just about anything can be coaxed into working - at least as long as it doesn't involve some copy protection scheme relying on slightly iffy RS232 timing and a dongle.
bdavis__ 7y ago
Guessing a 141T ?
- ChuckMcM 7y ago
  Good guess, but my date was wrong. It wasn't 1974 it was in the early 90's apparently (8596E btw). I suspect there is a decoder ring for the serial number which would tell me exactly. I've updated the date in my original comment.
  - blattimwind 7y ago
    The first two digits of the serial number gives the years since 1960 of the revision for HP.
    - ChuckMcM 7y ago
      Hmm, well then it would be 1999, first two digits are 39.
      - bdavis__ 7y ago
        i would expect any HP RF test equipment from any age to be fixable and usable (worse case, perhaps new vacuum tubes!)
  - madengr 7y ago
    Can’t beat 20th century HP test equipment. The pinnacle of quality. I have an 8566B at home. These things are built like tanks, and were made to operate in high temperature environments. We had about 10 of them at work, and the only things that would fail (slowly) are the CRT supplies. I’ll get the LCD retrofit when that happens.
    - bdavis__ 7y ago
      Have used one of those ! The 'automation' for its time was great. And calibration; signal amplitude measurements were always right on.
cosmodisk 7y ago
Why are they so expensive?
- catmanjan 7y ago
  Maybe because they've figured out they're "one and done"?
- detaro 7y ago
  Because they're incredibly complex, need to be long-term reliable and are made in small-ish numbers, sold to a small professional customer base.
- blattimwind 7y ago
  Broadly speaking test instruments often do similar things that some consumer devices do as well, but 1) with greater precision, accuracy and stability 2) over a much wider range of parameters. For example, a spectrum analyzer is similar to a radio receiver, but the SA usually covers a much larger rage (typically 9 kHz - 1.8, 5, 12 GHz), the SA can handle a huge range of input powers (typically something like -1xx to +20 dBm), and it can accurately measure power levels at all frequencies, has a variety of filters and analysis functions and so on. The RF section of some of these is actually mostly made of standard COTS parts - input assembly (these use very high grade connectors because of the repeatability requirements), programmable precision attenuator, mixer module, YIG LO etc. -- except all of these are high precision, RF devices, which simply cost a lot of money. The 80/20 rule applies as well. Well, maybe more like 60/40. An SDR can get you most of the stuff a proper SA can do for a fraction of the price (and can do some things an used SA from the 80s or 90s cannot do). A very good audio interface can serve as an audio analyzer, given the right software. A common pattern is that you can get the capabilities to do something, but not the accuracy of a real test instrument.
  - gmueckl 7y ago
    One aspect that drives cost is that high precision circuits often need a few parts that have tighter tolerances than the typical 5% or 1% that are usually good enough for 99% of use cases. And these parts are a lot more expensive.
blattimwind 7y ago
> So what to do when your sales are "one and done" ? It is a hard problem from a business model perspective. The vendor's responses since the ~90s is pretty much that they do trade-ins and crush the old gear. That is one of the reasons (the other being outsourcing) why test instruments made in the last ~20-25 years are much rarer in EU/US compared to older gear.
mike50 7y ago
Sure when you can't find connectors, power cables, comparable software or accessories. You got your instrument compared to a traceable reference but good luck getting an adjustment or repair performed. This only applies to dumb instruments (power supplies and dc electronic loads) but remember the technology you are measuring is eventuality going to have performance that exceeds your ability to test.
- dreamcompiler 7y ago
  What is this "software" you speak of? Seriously, I strongly prefer test equipment from the pre-software era. Test equipment shouldn't have to boot, and it shouldn't be dependent for its operation on the shitty non-realtime junk we call operating systems nowadays.
  - ChuckMcM 7y ago
    As do I. That said, there is something to be said for the economics of using software to compensate for manufacturing tolerances in hardware. 3D printers are a good example of taking a crappy platform and making it perform reasonably precise things using clever software. Of course sometimes that software is in an FPGA design :-). I expect that once the Xilinx RFSOC starts ending up in test gear you'll see some more cost effective GHz gear but very unhackable due to the FPGA nature of things. Of course no amount of software is going to make the front end conditioning circuits quieter (well I suppose simulating them and designing from that might but not on the instrument itself). That will always need a certain expertise to design and implement.
  - InitialLastName 7y ago
    I dunno, I've been doing a lot of RF analysis lately as my company has been re-upping our capabilities in that regard. We went from an 80's spectrum analyzer (the Rohde and Schwarz rep laughed at us when we called to ask for calibration data... "that machine was made before you were born") hooked up to an ink plotter to a mid-level Rigol analyzer. It really made me appreciate being able to recall the settings for the scan I ran last week, dump the data for the new scan, baselines and a few variations I wanted to try, and compare them all in Excel back at my desk (alongside the results from the external compliance lab).
robomartin 7y ago
Here's where I have to chime-in with a reality that people have yet to experience and most don't know about: The unintended negative consequences of RoHS. I have over a dozen instruments and several tools that are, in some cases, over 30 years old. I think all of my scopes, signal generators, DVM's, logic analyzers, DSO's, probes, lab power supplies, etc. are pre-RoHS and, in most cases, significantly so. The transition to RoHS, while, in principle, well-intentioned, is likely to prove to have been a massive mistake. Lead-free solder has one major problem: Tin whiskers. One way to think about this is that all RoHS electronics has a stochastic failure rate. I have devoted more time than I care to admit studying tin whiskers in the context of my work in aerospace. I have, in that process, consulted with NASA scientists who were are the forefront of long term research on the subject. The most salient take-away was that we had no way to predict or truly mitigate tin whiskers. The only mitigation in aerospace is to, quite literally, send chips to services that remove all lead-free solder from the pins (or remove balls from BGA's) and replace them with conventional lead solder. If this plays out as it could, landfills are going to be piled sky-high with broken electronics. From phones to laptops, TV's, ovens, clocks...anything really. And cars, yes, cars! Lead-free RoHS solder is a ticking time bomb and, in my opinion, one of the most misplaced decisions made in the name of protecting the environment. I have HP-41 calculators I bought in the early '80's that still work as new today. That's to say they are nearly 40 years old. There is no way a RoHS compliant calculator will survive 40 years. That is nearly impossible. And so, millions of them will end-up in landfills. Well done European Union, you really helped the planet with that one! For those not familiar with RoHS issues (a deep and wide topic), here's a starting point: https://nepp.nasa.gov/whisker/reference/tech_papers/2006-Leidecker-Tin-Whisker-Failures.pdf https://nepp.nasa.gov/whisker/reference/tech_papers/2006-Lei... This is very real.
- dredmorbius 7y ago
  TIL: RoHS == Reduction on Hazardous Substances. https://en.wikipedia.org/wiki/Restriction_of_Hazardous_Substances_Directive https://en.wikipedia.org/wiki/Restriction_of_Hazardous_Subst...
  - hadlock 7y ago
bsder 7y ago
> This situation (lack of schematics) is powering the open source test instrument surge. Actually, I would argue that the expense of tech support is what is powering the open source test instrument surge. Unless I can sell you a $20,000 instrument and cut you off after 3 years, my support costs are probably unsustainable. This means that anything worth less than $20,000 is unprofitable (case in point: the Tektronix USB Real Time Spectrum Analyzers). So, the only way around that is to make it worth even LESS and make it open source. Now, your tech support is the internet at large. Good luck with that.

wbl 7y ago

Make instruments and sell them like furniture makers, carpenters, most kinds of law (how many wills do you need?) etc

ChuckMcM 7y ago
Sort of a 'make on demand' model. It might work. These days it is hard to find parts that don't get end-of-lifed after 5 years, so you're re-doing schematics and thus your instrument's PCB. You could perhaps make a modular structure such that the instrument was constructed from modules but I'm not sure how well that would work. The open source trend is to put the instrument in its box and connect via USB to a computer that provides the UX. That works but has the issue of computer operating system compatibility. I've got a USB scope in my junk drawer that has a UI that only works on Windows 98. Not too useful these days, and the company is out of business. The instrument control protocol standards help here.
- blattimwind 7y ago
  To some extent standardized assemblies have been used for a very long time. HP System 2 (the cute 1/3 rack units) is from the 60s, System 3 from the late 70s (I think), though the actually walked back on that one and later replaced the standardized cast aluminium parts with unit-specific sheet metal bending (3478A and others). Later they re-used the display/input modules, both HP and Keithley did this for a lot of their later DMMs and SMUs.
- colonwqbang 7y ago
  I assume that the program that only ran on Win 98 is not open source. If it was, chances are someone would have ported it to Linux by now.
  - ChuckMcM 7y ago
    You would be correct. Of course it is just a USB 2.1 box and enumerates as a HID device and a bulk data endpoint so presumably spending some time with a USB protocol analyzer and running it through its paces would illuminate some aspects of its operation. This is why its still in my junk box and not in an ewaste skip somewhere :-)
    - simcop2387 7y ago
      What model is it? There's a non-zero chance that someone has done that work already and made it work via sigrok, https://sigrok.org/wiki/Supported_hardware#Oscilloscopes https://sigrok.org/wiki/Supported_hardware#Oscilloscopes
- lb1lf 7y ago
  -Perhaps a stupid question, but wouldn't that UI live and thrive inside a Win98 VM? (I am cursed by the instrumentation gods - I have to keep all sorts of late-paleolithic configuration software running to support the ditto hardware we still rely on for specific tasks in our service department. I've found that just about anything can be coaxed into working - at least as long as it doesn't involve some copy protection scheme relying on slightly iffy RS232 timing and a dongle.

bdavis__ 7y ago

Guessing a 141T ?

ChuckMcM 7y ago
Good guess, but my date was wrong. It wasn't 1974 it was in the early 90's apparently (8596E btw). I suspect there is a decoder ring for the serial number which would tell me exactly. I've updated the date in my original comment.
- blattimwind 7y ago
  The first two digits of the serial number gives the years since 1960 of the revision for HP.
  - ChuckMcM 7y ago
    Hmm, well then it would be 1999, first two digits are 39.
    - bdavis__ 7y ago
      i would expect any HP RF test equipment from any age to be fixable and usable (worse case, perhaps new vacuum tubes!)
- madengr 7y ago
  Can’t beat 20th century HP test equipment. The pinnacle of quality. I have an 8566B at home. These things are built like tanks, and were made to operate in high temperature environments. We had about 10 of them at work, and the only things that would fail (slowly) are the CRT supplies. I’ll get the LCD retrofit when that happens.
  - bdavis__ 7y ago
    Have used one of those ! The 'automation' for its time was great. And calibration; signal amplitude measurements were always right on.

cosmodisk 7y ago

Why are they so expensive?

catmanjan 7y ago
Maybe because they've figured out they're "one and done"?
detaro 7y ago
Because they're incredibly complex, need to be long-term reliable and are made in small-ish numbers, sold to a small professional customer base.
blattimwind 7y ago
Broadly speaking test instruments often do similar things that some consumer devices do as well, but 1) with greater precision, accuracy and stability 2) over a much wider range of parameters. For example, a spectrum analyzer is similar to a radio receiver, but the SA usually covers a much larger rage (typically 9 kHz - 1.8, 5, 12 GHz), the SA can handle a huge range of input powers (typically something like -1xx to +20 dBm), and it can accurately measure power levels at all frequencies, has a variety of filters and analysis functions and so on. The RF section of some of these is actually mostly made of standard COTS parts - input assembly (these use very high grade connectors because of the repeatability requirements), programmable precision attenuator, mixer module, YIG LO etc. -- except all of these are high precision, RF devices, which simply cost a lot of money. The 80/20 rule applies as well. Well, maybe more like 60/40. An SDR can get you most of the stuff a proper SA can do for a fraction of the price (and can do some things an used SA from the 80s or 90s cannot do). A very good audio interface can serve as an audio analyzer, given the right software. A common pattern is that you can get the capabilities to do something, but not the accuracy of a real test instrument.
- gmueckl 7y ago
  One aspect that drives cost is that high precision circuits often need a few parts that have tighter tolerances than the typical 5% or 1% that are usually good enough for 99% of use cases. And these parts are a lot more expensive.

blattimwind 7y ago

> So what to do when your sales are "one and done" ? It is a hard problem from a business model perspective. The vendor's responses since the ~90s is pretty much that they do trade-ins and crush the old gear. That is one of the reasons (the other being outsourcing) why test instruments made in the last ~20-25 years are much rarer in EU/US compared to older gear.

mike50 7y ago

Sure when you can't find connectors, power cables, comparable software or accessories. You got your instrument compared to a traceable reference but good luck getting an adjustment or repair performed. This only applies to dumb instruments (power supplies and dc electronic loads) but remember the technology you are measuring is eventuality going to have performance that exceeds your ability to test.

dreamcompiler 7y ago
What is this "software" you speak of? Seriously, I strongly prefer test equipment from the pre-software era. Test equipment shouldn't have to boot, and it shouldn't be dependent for its operation on the shitty non-realtime junk we call operating systems nowadays.
- ChuckMcM 7y ago
  As do I. That said, there is something to be said for the economics of using software to compensate for manufacturing tolerances in hardware. 3D printers are a good example of taking a crappy platform and making it perform reasonably precise things using clever software. Of course sometimes that software is in an FPGA design :-). I expect that once the Xilinx RFSOC starts ending up in test gear you'll see some more cost effective GHz gear but very unhackable due to the FPGA nature of things. Of course no amount of software is going to make the front end conditioning circuits quieter (well I suppose simulating them and designing from that might but not on the instrument itself). That will always need a certain expertise to design and implement.
- InitialLastName 7y ago
  I dunno, I've been doing a lot of RF analysis lately as my company has been re-upping our capabilities in that regard. We went from an 80's spectrum analyzer (the Rohde and Schwarz rep laughed at us when we called to ask for calibration data... "that machine was made before you were born") hooked up to an ink plotter to a mid-level Rigol analyzer. It really made me appreciate being able to recall the settings for the scan I ran last week, dump the data for the new scan, baselines and a few variations I wanted to try, and compare them all in Excel back at my desk (alongside the results from the external compliance lab).

robomartin 7y ago

Here's where I have to chime-in with a reality that people have yet to experience and most don't know about: The unintended negative consequences of RoHS. I have over a dozen instruments and several tools that are, in some cases, over 30 years old. I think all of my scopes, signal generators, DVM's, logic analyzers, DSO's, probes, lab power supplies, etc. are pre-RoHS and, in most cases, significantly so. The transition to RoHS, while, in principle, well-intentioned, is likely to prove to have been a massive mistake. Lead-free solder has one major problem: Tin whiskers. One way to think about this is that all RoHS electronics has a stochastic failure rate. I have devoted more time than I care to admit studying tin whiskers in the context of my work in aerospace. I have, in that process, consulted with NASA scientists who were are the forefront of long term research on the subject. The most salient take-away was that we had no way to predict or truly mitigate tin whiskers. The only mitigation in aerospace is to, quite literally, send chips to services that remove all lead-free solder from the pins (or remove balls from BGA's) and replace them with conventional lead solder. If this plays out as it could, landfills are going to be piled sky-high with broken electronics. From phones to laptops, TV's, ovens, clocks...anything really. And cars, yes, cars! Lead-free RoHS solder is a ticking time bomb and, in my opinion, one of the most misplaced decisions made in the name of protecting the environment. I have HP-41 calculators I bought in the early '80's that still work as new today. That's to say they are nearly 40 years old. There is no way a RoHS compliant calculator will survive 40 years. That is nearly impossible. And so, millions of them will end-up in landfills. Well done European Union, you really helped the planet with that one! For those not familiar with RoHS issues (a deep and wide topic), here's a starting point: https://nepp.nasa.gov/whisker/reference/tech_papers/2006-Leidecker-Tin-Whisker-Failures.pdf https://nepp.nasa.gov/whisker/reference/tech_papers/2006-Lei... This is very real.

dredmorbius 7y ago
TIL: RoHS == Reduction on Hazardous Substances. https://en.wikipedia.org/wiki/Restriction_of_Hazardous_Substances_Directive https://en.wikipedia.org/wiki/Restriction_of_Hazardous_Subst...
- hadlock 7y ago

bsder 7y ago

> This situation (lack of schematics) is powering the open source test instrument surge. Actually, I would argue that the expense of tech support is what is powering the open source test instrument surge. Unless I can sell you a $20,000 instrument and cut you off after 3 years, my support costs are probably unsustainable. This means that anything worth less than $20,000 is unprofitable (case in point: the Tektronix USB Real Time Spectrum Analyzers). So, the only way around that is to make it worth even LESS and make it open source. Now, your tech support is the internet at large. Good luck with that.