New spectrum analyser versus second hand - Page 1
Forum section: electronics / testgear

author: Ross
author_rank: Contributor
timestamp: July 16, 2018, 10:40:08 pm
content: Hi all,I have been looking at spectrum analysers, primarily for EMC pre-compliance. I have seen a couple on Ebay second hand HP8591EM (which are going for about US$2,100, including freight)Compare this to a Siglent SVA1015X (USD$1844, including EMC hardware) or the Rigol DSA815 (US$2390, including EMC hardware and software, $1,891 without software).Comparing the main specs of the three units, range, RBW, DANL, etc, seem to be similar.I am no expert in test gear, so my question to you is why would you buy the HP unit in this case?

author: nctnico
author_rank: Super Contributor
timestamp: July 16, 2018, 11:09:40 pm
content: What kind of EMC pre-compliance are you looking for? You can forget about radiated emission for starters because you'll need antennas and an insanely expensive test chamber.Any decent spectrum analyser is useful for hunting down EMC problems. As soon as you have a report from a test house which has used calibrated test setups and equipment to measure the excesses you can look at those frequencies and change the circuit to get a reduction in the emissions. You don't really need specific EMC options for that. Averaging the trace works well enough.I'd look at a reasonably modern Advantest spectrum analyser (with color TFT screen) or the Siglent SSA3021X (the latter can be liberated to 3GHz). You'll also need some H field probes.

author: tautech
author_rank: Super Contributor
timestamp: July 17, 2018, 12:24:34 am
content: Quote from: Ross on July 16, 2018, 10:40:08 pmThere's no need to buy the options initially as all are active for a trial time. If you squiz at Dave's SVA teardown there's a glimpse at the option UI showing permanent options and those with trial times remaining. IIRC they where far in excess of what's offered with the SSA3kX series so there's every chance the trial times would get you through your immediate needs. I'll know more when I get a SVA in a couple of days.(looking like tomorrow)QuoteLittle reason why the HP would be attractive unless you 'must' have an HP SA and a few hundred more MHz BW plus they're no small unit unlike modern equipment with an LCD display. Put it against the attractiveness of a 3yr warranty and the additional functionality of SVA.....well, your call.As already said, the SSA3021X could do your EMI stuff too and they're very popular for exactly this.I've got one left if you want to put your name on it.On this subject of EMI testing, hunt out dazz1's posts as he's on this path too. He's in Welly if that's close to you.Happy hunting.

author: Mechatrommer
author_rank: Super Contributor
timestamp: July 17, 2018, 01:27:37 am
content: Quote from: Ross on July 16, 2018, 10:40:08 pmbrand name and trustworthiness. but used item may be in it end of life cycle you may want to watch on that.

author: innkeeper
author_rank: Unknown
timestamp: July 17, 2018, 04:11:11 am
content: are their budget considerations?

author: hendorog
author_rank: Super Contributor
timestamp: July 17, 2018, 07:18:43 am
content: Quote from: Ross on July 16, 2018, 10:40:08 pmI wouldn't bother with an HP859x when you consider the risk of shipping damage, and the age and reliability etc. These were the low end of the HP range.I'd be a little bit more prepared to take that risk for something like an HP 8560 or 8561The SSB phase noise spec is where the difference is.Definately the Siglent SVA or SSA over the Rigol DSA for me for the same reason.

author: Mr. Scram
author_rank: Super Contributor
timestamp: July 17, 2018, 07:24:30 am
content: Quote from: nctnico on July 16, 2018, 11:09:40 pmA test chamber should reduce background noise, but you should at least be able to tell whether you're in trouble with background noise included. I'm not sure about the antennas though.

author: Berni
author_rank: Super Contributor
timestamp: July 17, 2018, 07:32:09 am
content: The rigol is pretty capable and comes at a good price, the new siglent looks like it might be great too.But for EMC do not underestimate the value of a shielded chamber. There is all sorts of crap on the air being spewed out by transmitters. So unless you live in the middle of the desert or a rainforest you will have a hard time telling apart what your device is and what that damn strong FM radio station is. Also cell phones spew out a lot of crap.But even other equipment can barf out EMI. We found wired USB keyboards showing up from across the room, or 3D printers jamming entire areas of the band.

author: RFDUK
author_rank: Regular Contributor
timestamp: July 17, 2018, 08:21:51 am
content: Hello Ross,I've used HP 8590 series analysers for EMC pre comp testing for 30 years and have also had an SSA3032X for 6 months.In the early days I used a free running (not synth) HP 8590A with a home made crystal marker for 1, 10 and 100 MHz with comb generator. Used home made biconical and dipoles for radiated emissions. Happy days.Had HP 8591EM for 20 years now. You will need the HP 08590-10027 Measurement Card with Setups, Limit Lines and Correction Factor tables. These are often separated from the analyser, but do appear on ebay individually for a couple of hundred US $.To your question, a few thoughts ...The basic HP 8591E comes a lot cheaper than the EM variant, now well under US $1000 for a 8591E. You loose the 9kHz and 120 kHz EMC RBW, but 10 and 100 kHz of the standard 8591E are fine for pre-compliance needs. You loose the CISPR spec average detector, although video averaging is good for precomp, you loose the CISPR QP detector and that's the main hardware loss really and probably a must have. The card setups are lost too. It may be a useful try and see how you get on option at very low cost?In 30 years of almost daily operation of 3 HP 8590 series, I had one PSU fault on the old HP 8590A. There are gazillions of old units out there for spares now. Watching friends experiences I wouldn't recommend buying older Advantest instruments because of reliability issues, sorry to Advantest champions.At under US $2000 the HP 8591EM is looking great value to me. The Siglent with standard preamp has a much lower DANL and your going to need an external preamp on the HP 8591EM for Class B radiated emissions tests. But that's not too costly.I use HP E4444A Bench Link software for screen captures. This is an area where the Siglent excels by comparison. I don't have the Siglent EMC software so can't comment on that.You don't mention your experience with EMC testing so I might be preaching to the converted, but you do not need a screened room to carry out meaningful tests. What you need is experience and patience and an interest in what you're doing. If you want to automate tests and have them run by a relatively inexperienced tech, then you need a semi anechoic chamber.In summary ... I bought the Siglent for general purpose radio dev apps and for portability. If my HP 8591EM broke I'd try and find another to replace it for my EMC work, I think they are a bargain.Then again if I was 30 years younger and not wedded to the old kit, maybe I'd make a different choice, the Siglent 3 year warranty is REALLY attractive!Like I've said on other threads, the Siglent SSA is a very nice instrumentMartyn.

author: dazz1
author_rank: Frequent Contributor
timestamp: July 17, 2018, 11:18:12 am
content: HiI have been down this road and made the decision to buy new. Soooo many things can go wrong with e-bay and the cost of shipping in test equipment makes it too expensive to just abandon to a learning experience. If the equipment gets damage, the seller will blame the shipper. The shipper will blame poor packaging. e-bay doesn't care. Even if it does arrive safely, local support is likely to be an issue.I brought a Siglent SSA for pre-compliance testing. It is capable of far more than the HPs I used to use. I am about to start making biconical antennas. The calibration process will require duplicate antennas. Once calibrated, I will have spare antenna available to sell.Dazz

author: Ross
author_rank: Contributor
timestamp: July 19, 2018, 02:04:11 am
content: Wow, thanks everyone for the quick responses. To answer your questions:I am just looking at conducted emissions at the moment (so would also need build or get a LISN) as this is where my problem lies. As for budget, there isn't a specific amount, but the pot of money is not large, what is spent here means there is not much to be spend next time.Quote from: hendorog on July 17, 2018, 07:18:43 amNoted.@Martyn, I used HP gear when I was at Uni and have good and bad memories (later were due to more PEBCAK related issues, but all learning experiences). There seem to be a lot of HP gear on EBay, which seems to get sold and my feeling that is that some items you can get a good deal as a new unit for the same specs would be $10k+. Hence my post. If money wasn't an issue I would by something Techtonics/Keysight, of course overkill for what I do.Quote from: dazz1 on July 17, 2018, 11:18:12 amI think you (and others) are correct there is more of an risk with second hand items with regard to fright. The HP unit I am watching is from a instrumentation 2nd hand dealer and I expect they will put some effort into packaging, although nothing is going to protect a package from a drop out of a cargo door of a 747...Once again thanks for your replies.Ross

author: Berni
author_rank: Super Contributor
timestamp: July 19, 2018, 06:28:29 am
content: Typically the advantage the big HP boat anchors have is phase noise. But you tend to miss modern comforts such as USB drives, USB device port, Ethernet etc.We found that Automation over SCPI was very useful for EMI work even if my automation is still in the form of a thrown together Excel VBA app. It very useful to capture a waveform on a large chart at the click of a button. Often EMI involves a lot of comparative tests to see if your EMI counter measures are actually helping.I have a good bit of big heavy HP gear and yes sometimes it gets cosmetic damage if it's not packed properly (No a bit of crumpled up newspaper is not proper packing for a 20kg PSU). Shipping went well n general. My spectrum analyzer is a 50 kg monochrome HP beast from the 80s. It's big, it's loud, it uses a lot of power but it does go from 100Hz to 22GHz

author: tautech
author_rank: Super Contributor
timestamp: July 19, 2018, 07:21:22 am
content: Quote from: Berni on July 19, 2018, 06:28:29 amYes, but not by a large margin.See:https://www.eevblog.com/forum/testgear/phase-noise-head-to-head-siglent-ssa3032x-vs-hp-8566b-vs-signalhound-sa124b/