Pre-compliance test equipment. Tektronix 492 versus HP8594, HP 8558b - Page 1
Forum section: electronics / testgear

author: Pannenkoek_met_een_lampje
author_rank: Contributor
timestamp: July 18, 2017, 07:55:03 pm
content: Hello I am new here,I want to build dc dc converters and play with canbus communication I want to see if i meet the EMC rules. For this reason I want to see if i can buy some equipment. I saw a HP8594, HP 8558b and a Tektronix 492. Did read that the Rigol 815 was a good option but that is a lot of $$$. Dont know where to look for in the specs except for frequencies.years ago I did some EMC testing, it was some ferrite coil connected to a spectrum analyzer think I also need such a thing. At that time 1.5 gig was more than sufficient but maybe the frequencies you have to test have gone up?Can someone point me in the right direction? Tell me what I could use? Maybe the 21 GHz of the tek is too high and makes it too expensive, maybe the HP8558 is too old and will break down easy? Can someone please give me a start on this subject?I see a lot of scopes with 0V DC on the input, will it break down if there is a small dc? Can you protect the analyzer from this situation with standard parts?Hope you guys can help!

author: KE5FX
author_rank: Super Contributor
timestamp: July 18, 2017, 08:10:42 pm
content: Get the Rigol. These are all relatively old models that won't do a good job at what you're looking to do and that will probably take a lot of work to keep running, especially the older 492.

author: Pannenkoek_met_een_lampje
author_rank: Contributor
timestamp: July 18, 2017, 08:31:00 pm
content: Yes I know the Rigol is a good machine but it is a lot of $$$. Besides the change of breaking down what else will be annoying? I did read the resolution of the Rigol is 10 Hz versus the old machines about 10kHz what resolution is needed for emc compliance testing?

author: nctnico
author_rank: Super Contributor
timestamp: July 18, 2017, 08:46:32 pm
content: Look for an Advantest R3131 or R3131A. These are not very expensive and will work fine for what EMC pre-compliance testing.

author: Pannenkoek_met_een_lampje
author_rank: Contributor
timestamp: July 18, 2017, 08:55:40 pm
content: Can you please tell me why these are a good option is it only the price of some features? Asking because I want to learn. Thanks I try to find them on E-bay

author: nctnico
author_rank: Super Contributor
timestamp: July 18, 2017, 09:08:03 pm
content: Quote from: Pannenkoek_met_een_lampje on July 18, 2017, 08:55:40 pmThey are compact, quiet, not too old and Advantest spectrum analysers don't have the Tektronix and HP price bloat. IIRC they also have EMC testing abilities like quasi peak but in my experience there is not much use for that without a real testing chamber. The going price should be around 600 to 900 euro. IIRC forum member Fraser may have some R3131s.

author: Pannenkoek_met_een_lampje
author_rank: Contributor
timestamp: July 19, 2017, 05:26:48 am
content: Thank you for the info! What does the quasi peak do ?

author: Gribo
author_rank: Frequent Contributor
timestamp: July 19, 2017, 01:06:34 pm
content: It is a type of detector, required for EMC tests.

author: Pannenkoek_met_een_lampje
author_rank: Contributor
timestamp: July 19, 2017, 07:26:37 pm
content: Just read the wiki:https://en.wikipedia.org/wiki/Quasi-peak_detectorIf I put it in my own words, there is a standards which describes a specific shape of a peak like the hight rise time and decay time.For now I asume this peak is a shape you can also see on a NON-quasi peak detector spectrum analyzer, but you will not have a text or a beep telling you the EMC test is not passed, is this correct?So I could focus on trying to find a spectrum analyzer with a quasi peak detector, but what if I would buy a too old one? Maybe the shapes described by new standards are not in there? Maybe 1% of them or maybe 90% of them are not in? Can that be?

author: nctnico
author_rank: Super Contributor
timestamp: July 19, 2017, 07:59:29 pm
content: A quasi-peak-detector on a spectrum analyser has little use unless you have an EMC testing chamber. Quasi peak is very slow so during real EMC tests the operator will take a quick average sweep over the frequency band and then use quasi peak on the frequencies where the emissions are strongest to check pass/fail. If your device fails on emissions you need to ask for a graph or table with the frequencies which your devices fails. From there you can use a spectrum analyser in normal mode to figure out which part of the circuit is causing problems. Some H-field probes are good investment.

author: Rbastler
author_rank: Frequent Contributor
timestamp: July 19, 2017, 08:01:43 pm
content: I tried to use a Tek 492 once, and I must say i'ts quite hard to use. The Rigol DSA815-TG is much easier to use and has much more capabilities.

author: skipjackrc4
author_rank: Regular Contributor
timestamp: July 20, 2017, 03:02:46 am
content: Quote from: Rbastler on July 19, 2017, 08:01:43 pmAgreed. I use multiple spectrum analyzers every day professionally, and I have a Tek 492 at home. I still have no idea how to use that thing well.

author: Pannenkoek_met_een_lampje
author_rank: Contributor
timestamp: July 20, 2017, 10:43:40 pm
content: Quote from: skipjackrc4 on July 20, 2017, 03:02:46 amJust curious, what do you use them for?

author: Pannenkoek_met_een_lampje
author_rank: Contributor
timestamp: July 20, 2017, 10:46:05 pm
content: Quote from: nctnico on July 18, 2017, 09:08:03 pmDid take a look, think it @#$@#$% that I live in Europe never see those for that price here :-( While there are plenty in the US But the shipping / import costs to get them here are so high it is not the effort :-(

author: idpromnut
author_rank: Unknown
timestamp: July 21, 2017, 01:39:58 pm
content: I don't think anyone answered the part about the 0VDC input tolerance: you absolutely do NOT want to apply a DC voltage over the rated max input VDC (it might be higher than 0 VDC depending on the spectrum analyzer). To protect against this, you can use a DC block (google that), and depending on the measurement(s) you are making, you might want to add an attenuator (but I don't think it would be needed for EMC testing).I didn't quite catch if this was all for self education/challenge, or if this was for work. If it is for work, then don't screw around; the cost of even a new Rigol with EMC testing package + probes will be well worth the time saved instead of multiple trips to the EMC testing facility.If it's for personal fun, then be all means, Have fun!