Stanford Research Systems - any opinion?  - Page 1
Forum section: electronics / testgear

author: Hydrawerk
author_rank: Super Contributor
timestamp: March 27, 2014, 06:18:34 pm
content: Well, I came across this company from USA. What do you think about them? I think that their equipment is durable and long lasting, but why do they keep the look of 1980's Hewlett Packard products? Stanford Research probably never uses any LCD graphic display. Their products look so old-fashioned, but why? Even GW Instek stuff looks more modern.

author: Hydrawerk
author_rank: Super Contributor
timestamp: March 27, 2014, 06:19:51 pm
content: More photos... And here is their webpage.http://www.thinksrs.com/products/prod.htm

author: Hydrawerk
author_rank: Super Contributor
timestamp: March 27, 2014, 06:22:18 pm
content: Here is some 1980's HP stuff for comparison.

author: Hydrawerk
author_rank: Super Contributor
timestamp: March 27, 2014, 06:26:24 pm
content: I have seen their instrument at a trade fair.

author: bingo600
author_rank: Super Contributor
timestamp: March 27, 2014, 07:28:12 pm
content: I'd love that CNT-90 Counter/Bingo

author: Vgkid
author_rank: Super Contributor
timestamp: March 27, 2014, 07:57:34 pm
content: From what i have seen browsing their manuals, is that it is simple, really accurate, well designed, expensive on the used market when compared to HP et all.

author: edavid
author_rank: Super Contributor
timestamp: March 27, 2014, 08:46:15 pm
content: They seem to be quite a small company (hard to say exactly since their sales figures, number of employees, etc. are secret), and most of their products are high end, niche market, low volume. So, they don't spend a lot on developing new cabinets and displays.

author: free_electron
author_rank: Super Contributor
timestamp: March 27, 2014, 08:57:40 pm
content: Because most of these machines were designed in the 80's and are still in production.this is a 30-odd people company. I have a few of their instruments.That DSA for example is such an old design that the DSP's and half of the opamps in it are obsolete.

author: edavid
author_rank: Super Contributor
timestamp: March 27, 2014, 09:06:08 pm
content: Their new products don't look any different...

author: Hydrawerk
author_rank: Super Contributor
timestamp: March 27, 2014, 09:21:57 pm
content: That DSA uses CRT, that is very rare nowadays.

author: VK5RC
author_rank: Unknown
timestamp: March 27, 2014, 10:50:10 pm
content: The counters are some of the best there are , time nuts rave about them, SRS620 only just been beaten 25pS accuracy!

author: dc101
author_rank: Regular Contributor
timestamp: March 27, 2014, 11:17:11 pm
content: A lot of the Agilent calibration manuals call for the Stanford Research Systems FS-725 rubidium frequency standard as THE standard to calibrate frequency against.

author: jfphp
author_rank: Regular Contributor
timestamp: March 27, 2014, 11:23:38 pm
content: Only big problem : they refuse to sell parts to a person other that the first buyer...

author: jpb
author_rank: Super Contributor
timestamp: March 27, 2014, 11:42:34 pm
content: They produce some quite good app notes e.g. their one on DDS:http://www.thinksrs.com/downloads/PDFs/ApplicationNotes/DDS.pdfI tend to judge a company on their app notes (like the HP of old and Analogue Devices for instance).But other than that I know nothing about them.

author: gaijin
author_rank: Contributor
timestamp: March 27, 2014, 11:51:36 pm
content: Looks like they aimed one of their rubidium standards at the audiophool market PERF10 Rubidium Audio Clock.

author: Hydrawerk
author_rank: Super Contributor
timestamp: March 28, 2014, 12:22:13 am
content: Most of their equipment even have no USB or LAN.

author: EEVblog
author_rank: Unknown
timestamp: March 28, 2014, 01:15:38 am
content: Quote from: Hydrawerk on March 27, 2014, 06:18:34 pmBecause their gear was designed in the 1980's and they still sell it. SRS is a company that seems very to happy to not expand and not update. People keep buying their stuff, so they keep producing and selling it. Kudos to that.Their stuff also has excellent service manuals, with theory of operation and full schematics, and mostly standard parts (if they aren't obsolete).

author: jpb
author_rank: Super Contributor
timestamp: March 28, 2014, 11:13:56 am
content: Quote from: VK5RC on March 27, 2014, 10:50:10 pmI found one of these for sale on e-bay so had a look at the spec. sheet.It is rather confusing. The resolution is 25 ps (plus other terms) but the error is 500 ps.I tried looking at the Agilent 53132A data sheet for comparison and that is even more confusing - its resolution is 150 ps and error is given by a load of terms combined.I guess if the error is consistent then having a resolution 20 times as fine as the error might still be useful as you can use it to measure change.EDIT : I've just read the manual and it has quite a useful explanation :LEAST SIGNIFICANT DIGIT (LSD)The LSD is the smallest displayed increment in a measurement. The SR620 has a 4ps single-shot LSD and thus the smallest amount that two single-shot time interval measurements may differ by is 4ps.RESOLUTIONResolution is the smallest difference in a measurement that the SR620 can discern. That is, the smallest statistically significant change which can be measured by the SR620. Resolution is of primary interest in comparing readings from the same instrument. The instrument resolution is limited by many things including short-term timebase stability, internal noise, trigger noise,etc. Because these processes are random in nature, resolution is specified as an rms value rather than a peak value. This rms value is the standard deviation of the measured value. The SR620's single-shot resolution is typically 25ps rms. This number can be improved by averaging over many measurements, or in the case of frequency and period measurements, increasing the gate time. The single-shot LSD is always smaller than the single-shot resolution.ERRORError is defined as the difference between the measured value and actual value of the signal being measured. The error in a measurement is of primary concern when the absolute value of the parameter being measured is important. Error consists of the random factors mentioned above and systematic uncertainties in the measurement. Systematic uncertainties include timebase aging, trigger level error, insertion delay, etc.. Systematic errors may always be measured and subtracted from subsequent measurements to reduce the error. The SR620's absolute error is typically less than 0.5ns for time interval measurements less than 1ms.DIFFERENTIAL NON-LINEARITYAbsolute error is of interest in determining how far a value is from the actual value. Often only the relative accuracy (the difference between two measurements) is important. Differential non-linearity is a measurement of the relative accuracy of a measurement and is specified as the maximum time error for any given relative measurement. The SR620's differential non-linearity is typically ±50ps. That means if the time interval is changed by some amount the SR620 will report that change to within ±50ps of that change.

author: colinbeeforth
author_rank: Contributor
timestamp: March 28, 2014, 11:26:29 am
content: I worked for an SR agent some years ago. The Stanford Research gear was well made, worked nicely and the specs were accurate, they are a quality manufacturer. Hardly ever saw them back for warranty unless someone had done something foolish. Pretty impressive specs on some of their models. Out of hobbyist price range new, but if some of it is coming onto the second hand market it might be more affordable.

author: jpb
author_rank: Super Contributor
timestamp: March 28, 2014, 11:30:38 am
content: Quote from: EEVblog on March 28, 2014, 01:15:38 amDoes this imply that they no longer employ engineers to design improvements or new stuff? I'm curious as to whether the company has become purely commercial with a few technicians to fix the returns.

author: EEVblog
author_rank: Unknown
timestamp: March 28, 2014, 11:35:01 am
content: Quote from: jpb on March 28, 2014, 11:30:38 amMaybe they don't bother with general purpose test gear anymore, but instead put their effort into the more obscure gear used for physics testing etc?In any case they are not a public company and hence don't have that pressure to continually show exponential growth each year.

author: VK5RC
author_rank: Unknown
timestamp: March 28, 2014, 11:56:39 am
content: Thanks jpb,I always interpreted the figure as 'accuracy' but clearly it states time interval resolution, the information in the graphs in the SR620 manual (in the section about resolution etc) to me look to me as if it appears to 'time' accurately to within +/- 25pS.The only term that appears to be used consistently across different manufacturers is the "single shot resolution", I must admit I haven't tracked down their respective definitions, after having more than 3 tabs open on a browser I seem to lose the ability to concentrate!I subscribed to the time nuts list but so much arrives I don't have time to read/digest it all but SR620 does feature often and with respect.I have a soft spot for LED 7 segment displays so the retro look doesn't really bother me, in fact the longer something is built I suspect all the bugs really get worked out. colinbeeforth's comments seem to bear this out.I suspect they have gone for a very small niche time market, the look doesn't really matter. Bit unusual though the restricted ability to link to PCs.Still I would be very happy to have a SR620 at home!

author: G0HZU
author_rank: Super Contributor
timestamp: March 28, 2014, 01:16:37 pm
content: QuoteSome of the products shown in this thread look like modern (state of the art?) designs because of the specs and capability they offer. For example: I seriously doubt the 6GHz Vector Sig gen is a 25 year old product. Its the last image in post #2. I would guess it's a very recent design. Just because it has an old school display technology doesn't mean it is 25 years old.

author: jpb
author_rank: Super Contributor
timestamp: March 28, 2014, 01:54:55 pm
content: Quote from: G0HZU on March 28, 2014, 01:16:37 pmYou're probably right but the specs alone don't exclude it from being 25 plus years old. I remember as a young engineer working with the HP8510 vector network analyser, this came out about 1982/3 and went as standard to 18GHz. We didn't use any SRS equipment in our lab, it was almost all HP and very expensive - I think the 8510 was around £500k (or perhaps it was $500k) at a time when I'd just bought my first flat for £23k!

author: G0HZU
author_rank: Super Contributor
timestamp: March 28, 2014, 03:09:38 pm
content: I didn't have access to the very best lab grade RF test gear until about 1990 and I can kind of remember how much the stuff cost back then. A decent HP VNA ran from around $25k to maybe $40k depending on model and any options ordered. At a guess I would expect the HP8510 cost <$40k new in the late 1980s. Maybe it cost a lot more when it was first brought out? $500k sounds a bit steep to me...QuoteIt isn't the 6GHz aspect of the performance that makes me think the SRS vector sig gen is modern. For example, even in WW2 the British/US troops in 1944 were using 4GHz wireless sets and microwave dishes with something like 8 channel TDM modes to communicate with HQ. It's the synthesiser resolution and the other technology the SRS generator offers in such a small footprint.

author: KJDS
author_rank: Super Contributor
timestamp: March 28, 2014, 03:23:34 pm
content: An HP8720C was about £80k new from memory. Certainly an 8753C was £25k new in it's 3GHz form. I've a feeling that an 8510C was about £200k, and it's rival the Wiltron 360 was about 2/3rds of that in the late 80s.

author: jpb
author_rank: Super Contributor
timestamp: March 28, 2014, 04:06:56 pm
content: It looks like I probably remembered too high a price for the 8510 - it is very hard to get any historic information on prices as these weren't published.The 8510 came out in 1984 (so I was a year or two out) and went to 26.5GHz, our previous instrument only went to 18GHz I think.KJDS - your figure of £200k in late 80s probably translates to £250k when it first came out - so it was only 10 times the cost of my flat and not 20 times.Given that my salary as an engineer at the time when I started in 1982 was £5k it was still about 50 times the salary of a new graduate.

author: G0HZU
author_rank: Super Contributor
timestamp: March 28, 2014, 04:24:28 pm
content: To clear up any confusion I think you must be quoting the price for a complete functioning HP rack system with the HP8510 VNA. eg you can soon bump up the cost of a rack system if you add an expensive sweep generator (or two) and a couple of $50k microwave s parameter test sets and bung in some options on all the above.QuoteI think the prices were published each year back in those days. About 20yrs ago I recall we had several big thick yearbooks from HP with all their product range listed for that year. In some of them they quoted the prices for (what seemed like) every HP product for that year.But I guess the price of HP stuff in 1989 isn't relevant to the thread anyway...

author: KJDS
author_rank: Super Contributor
timestamp: March 28, 2014, 04:35:37 pm
content: Quote from: G0HZU on March 28, 2014, 04:24:28 pmYou're right on both points, though an 8510C isn't much use without the sweep gen and s-parameter test set. A 26.5GHz cal kit isn't cheap either. The Rf test leads we £4,000

author: jpb
author_rank: Super Contributor
timestamp: March 28, 2014, 04:53:18 pm
content: Quote from: G0HZU on March 28, 2014, 04:24:28 pmYou're very right. I was rambling (or reminiscing) though I suppose it does support the argument that gear designed and built in the 1980s was done properly on relatively large budgets so SRS systems could still be useful today even if 1980s designs are being used.

author: G0HZU
author_rank: Super Contributor
timestamp: March 28, 2014, 05:24:12 pm
content: I still think the SRS 6GHz vector signal generator has to be a (very) modern design. No way is that a 1980s design.

author: free_electron
author_rank: Super Contributor
timestamp: March 28, 2014, 05:33:05 pm
content: that vector generator is indeed a new design. only a few years old.most of their other stuff is decades old

author: Scott
author_rank: Newbie
timestamp: March 28, 2014, 05:34:44 pm
content: They recently sent me a free part (plastic power button) for a function generator that I got from eBay. Back in grad school they sent me some free transistors for a delay generator with a blown output.Great gear.Quote from: jfphp on March 27, 2014, 11:23:38 pm

author: G0HZU
author_rank: Super Contributor
timestamp: March 28, 2014, 05:56:31 pm
content: Quote from: free_electron on March 28, 2014, 05:33:05 pmYes, I just looked through the user manual and it has various high performance MCU, DDS and FPGA devices in it that have modern part numbers.

author: VK5RC
author_rank: Unknown
timestamp: March 29, 2014, 04:45:28 am
content: One question I think may be relevant, I hear of modest problems with lcds but fewer with leds, could that be the reason Stanford have stayed with led in general? (in gear where power consumption is not critical)