O-scope advice - Page 1
Forum section: electronics / testgear

author: sdouble
author_rank: Frequent Contributor
timestamp: April 28, 2019, 05:03:59 pm
content: dear all,I am now after an advice. I need to upgrade my lab with a new scope.I'm dealing with analog stuff only. Bandwidth needs to be 400+ MHz, sampling rate of 1+ GS/s .My main concern is dynamic range. I would like a 10+ bits device with a low noise floor.I often try to monitor baselines from preamplifier outputs. They typically exhibit a noise level of 50-100 uV RMS over 10KHz - 20 MHz.I bought a Lecroy device a few years ago. I is now out of order. The digital part (in other terms, the computer) of the scope behaves very badly. A 12kEuros scope to be trashed...

author: egonotto
author_rank: Super Contributor
timestamp: April 28, 2019, 05:15:52 pm
content: Hallo,perhaps a Rohde & Schwarz RTM3004. It has low noise.Best regardsegonotto

author: Mr Nutts
author_rank: Regular Contributor
timestamp: April 28, 2019, 08:36:41 pm
content: Quote from: sdouble on April 28, 2019, 05:03:59 pmWhat do you mean with "behaving badly"? Does the scope swear at you?What model is that scope? And have you asked Lecroy how much it would cost to repair? I heard they have very good support even for older scopes

author: nctnico
author_rank: Super Contributor
timestamp: April 28, 2019, 08:47:25 pm
content: If it is the PC part then it is likely easy to fix.

author: sdouble
author_rank: Frequent Contributor
timestamp: April 28, 2019, 09:16:55 pm
content: Quote from: Mr Nutts on April 28, 2019, 08:36:41 pmit is a HDO4000, 500 MHz version scope, AKA HDO4054.repair cost is prohibitive . Lab director decided that it was not worthwhile.I think that we could say that it swears at me, yes. All buttons are inoperative after the boot sequence.

author: DaJMasta
author_rank: Super Contributor
timestamp: April 28, 2019, 09:28:46 pm
content: Probably repairable, but sounds like it will involve mucking around in the front panel or in the software, may not be worth the time unless you've got lots of it.I think for this general class of instruments, the current and previous generation R&S scopes are pretty solid choices. Otherwise, Keysight's newest line (S series and some others) which use the higher resolution converters, Tek's 5 and 6 series MDOs, and the more familiar LeCroy offerings. Not really sure where the preference/feature requirements puts things, but probably any of those would do the basic job well - competition and UI development have gotten to a point where while some interfaces/featuresets will stand out, everything will be fairly competent for standard scope use tasks.

author: sdouble
author_rank: Frequent Contributor
timestamp: April 28, 2019, 09:44:25 pm
content: the DSOS054A seems to be an interesting beast.

author: 2N3055
author_rank: Super Contributor
timestamp: April 28, 2019, 09:53:16 pm
content: Quote from: sdouble on April 28, 2019, 09:16:55 pmI'll take that piece of electronic waste ....

author: sdouble
author_rank: Frequent Contributor
timestamp: April 28, 2019, 10:00:50 pm
content: I would gladly give it away.. but i do not own it. it will certainly end in a trash somewhere.

author: 2N3055
author_rank: Super Contributor
timestamp: April 28, 2019, 10:34:34 pm
content: Quote from: sdouble on April 28, 2019, 10:00:50 pmWell, that is a shame..I would have liked to give it a try to repair it.. But it is what it is..Thank you for your goodwill anyways!!Regards / CordialementSinisa

author: Mr Nutts
author_rank: Regular Contributor
timestamp: April 28, 2019, 11:16:31 pm
content: Quote from: sdouble on April 28, 2019, 09:16:55 pmSo has it been with Lecroy to examine? HDO4054 is not that old, repairing it should be cheaper than a new scopeQuoteIt could be a software issue.You could ask in the Allaboutcircuit forum, there's a a guy who once was a member here but no longer, and who's an expert in Lecroy and other scopes who might be able to help you to get your HDO back into working conditionThe same guy is also very knowledgeable in all things of test equipment, he also knows the various weaknesses and should be able to give you a good recommendation for a replacement

author: egonotto
author_rank: Super Contributor
timestamp: April 28, 2019, 11:58:37 pm
content: Hello,do you mean Wuerstchenhund?Best regardsegonotto

author: tautech
author_rank: Super Contributor
timestamp: April 29, 2019, 12:05:04 am
content: Quote from: egonotto on April 28, 2019, 11:58:37 pmWho else ?

author: nctnico
author_rank: Super Contributor
timestamp: April 29, 2019, 12:15:40 am
content: Quote from: sdouble on April 28, 2019, 10:00:50 pmOh no...

author: Mr Nutts
author_rank: Regular Contributor
timestamp: April 29, 2019, 12:36:50 am
content: Quote from: egonotto on April 28, 2019, 11:58:37 pmYes, that's the guy. I learned a lot about scopes from him, and I sometimes message him with stupid questions and he always goes the extra mile to explain things when replyingAnd I don't think you will find many people who also know the other alternatives inside out. Probably not many members here have access to one of the other scopes, less so all of themWorth a try

author: sdouble
author_rank: Frequent Contributor
timestamp: April 29, 2019, 02:40:37 am
content: the scope is 4 years old i think, so it is not still under warranty. According to Lecroy it 's a hardware issue. They are pushing us to replace it. The boss agreed. I do not really care frankly speaking. I have been using lecroy scopes only at the lab for 2 decades, they are expecting me to buy one more. I'm a bit pissed off by their behavior though, i may be moving to another brand. That's basically the origin of this topic

author: tautech
author_rank: Super Contributor
timestamp: April 29, 2019, 02:51:19 am
content: Quote from: sdouble on April 29, 2019, 02:40:37 amYes, probably just a dead HDD. Recoverable, yes with a bit of work. Many drop a SSD into them for drastically improved boot times.Save it from the dumpster and take it home for a fix adventure.Replacement, have you looked at the SDS5054X ?

author: DaJMasta
author_rank: Super Contributor
timestamp: April 29, 2019, 03:15:18 am
content: 500uV/division range is fine and everything, but it's an 8 bit converter, which I think excludes it from consideration from the OP's list

author: tautech
author_rank: Super Contributor
timestamp: April 29, 2019, 04:24:51 am
content: Quote from: DaJMasta on April 29, 2019, 03:15:18 amReally, exclude ?Quote from: sdouble on April 28, 2019, 05:03:59 pmScopes with a properly implemented E-Res can assist here.

author: rf-loop
author_rank: Super Contributor
timestamp: April 29, 2019, 06:06:53 am
content: Quote from: tautech on April 29, 2019, 04:24:51 amEres reduces bandwidth. And then it need also look if this enhanced resolution is available out from scope or is it used only just for "cleaning" display as noise filter.As can see (image), example with Eres 2bit BW is 0.058 x fNyquist (so with 1GSa/s BW is bit under 30MHz. (of course some may use bit different parameters, this is from Teledyne LeCroy)Only good solution if need real full speed dynamic range is real 10, 12, 14 etc bits hardware. There is available good 12 bit scopes, example LeCroy HDO's.In this area there is no free lounges. Cheap solution and result is also "cheap".

author: sdouble
author_rank: Frequent Contributor
timestamp: April 29, 2019, 07:32:12 am
content: I really need a 10+ bits scope, excluding siglent products.I will not be allowed to take back home the lecroy scope . it is clearly not an option at my lab... unfortunately.Money is not a major issue there. We basically do not repair anything.

author: Someone
author_rank: Super Contributor
timestamp: April 29, 2019, 09:30:19 am
content: Quote from: sdouble on April 29, 2019, 07:32:12 amLecroy have a recent and broad review of the options with examples of noisefloor:http://cdn.teledynelecroy.com/files/whitepapers/comparing-high%20resolution-oscilloscope-design%20approaches-wp.pdf

author: nctnico
author_rank: Super Contributor
timestamp: April 29, 2019, 09:55:49 am
content: Quote from: sdouble on April 29, 2019, 07:32:12 amThe R&S RTM3004 could be an option to give 10 bit resolution but I have a feeling Lecroy has stronger math / analysis functions.

author: sdouble
author_rank: Frequent Contributor
timestamp: April 29, 2019, 10:29:56 am
content: btw, what are the main differences between RTA and RTM series ?

author: rsjsouza
author_rank: Super Contributor
timestamp: April 29, 2019, 11:01:16 am
content: Did you take a look at the Picoscope series of instruments? They usually feature 12~16bit ADCs and may be suitable for your specifications.https://www.picotech.com/I didn't see a limitation to bench-only equipment - these scopes are PC-based.

author: sdouble
author_rank: Frequent Contributor
timestamp: April 29, 2019, 12:08:10 pm
content: AFAIK picoscopes embed 8-bit ADCs.

author: nctnico
author_rank: Super Contributor
timestamp: April 29, 2019, 12:21:37 pm
content: AFAIK some Picoscope have >8 bit ADCs but you have to check the datasheets carefully because many rely on oversampling 8 bit indeed.

author: 2N3055
author_rank: Super Contributor
timestamp: April 29, 2019, 03:15:20 pm
content: Pico doesn't have anything with 10+ bits at 1GS/s and 400MHz bandwith...If 10 bits is ok R&S RTM3000 might be a good option..I would contact Keysight to see if they might have something Premium Used with full warranty. Prices are really good if they have something.And their maintenance support is good and more affordable than LeCroy.

author: JPortici
author_rank: Super Contributor
timestamp: April 29, 2019, 03:32:48 pm
content: Quote from: sdouble on April 29, 2019, 10:29:56 ammy gut tells me it's just what you see at a quick glance: more memory. To me, that doesn't justify the huge price difference between the same 200MHz models.Maybe there's more that what meets the eyes.. like a faster processor for faster UI

author: sdouble
author_rank: Frequent Contributor
timestamp: April 29, 2019, 04:45:09 pm
content: Quote from: JPortici on April 29, 2019, 03:32:48 pmThat was my impression too. I could not find anything but the larger memory.Could not find anything about maths though. There may be some differences there.

author: maginnovision
author_rank: Super Contributor
timestamp: April 29, 2019, 05:16:43 pm
content: I'm not sure since I don't have one to test but RTA may also have lower noise floor.

author: nctnico
author_rank: Super Contributor
timestamp: April 29, 2019, 05:18:35 pm
content: Luckily the RTA is expensive enough to get one on loan to play with for a while

author: Keysight DanielBogdanoff
author_rank: Unknown
timestamp: April 29, 2019, 05:42:11 pm
content: On the Keysight side, you could check out the 6000 X-Series InfiniiVision scope ("budget" bench top option) and the S-Series Infiniium scope (better for deep analysis). They both share the same front end hardware and have pretty good noise floors. The other InfiniiVision scopes have a different front end and are a bit more noisy than the 6000 X-Series.The 6000X starts at 1 GHz, and has a 115 uVrms noise floor (1mV/div, 1 GHz bandwidth).

author: Mr Nutts
author_rank: Regular Contributor
timestamp: April 29, 2019, 05:49:02 pm
content: Isn‘t the 6000X an 8 bit scope?

author: maginnovision
author_rank: Super Contributor
timestamp: April 29, 2019, 05:56:38 pm
content: Looks like the RTA at 1GHZ has about 110uV noise floor at 500uV/div.

author: sdouble
author_rank: Frequent Contributor
timestamp: April 29, 2019, 06:36:00 pm
content: thanks for the update.what is missing in the modern scopes is an adjustable low pass filter. It should be pretty simple to implement in those modern digital scopes. I personally often need a measurement at a given cutoff frequency. even better would be an adjustable high pass filter. Working with p-HEMT, I always face a huge low frequency noise, which is in principle not an issue after proper filtering but it makes all checks using scopes painful.

author: sdouble
author_rank: Frequent Contributor
timestamp: April 29, 2019, 06:40:38 pm
content: as mentioned by Daniel, the 6000X starts at 1 GHz, so no 500 MHz version. Additionally, the sampling ADC is 8-bit, which is a show-stopper here.thanks anyway.

author: Mr Nutts
author_rank: Regular Contributor
timestamp: April 29, 2019, 09:10:31 pm
content: Just had a conversation with that unnamed individual and mentioned this threadHe said if you can live with 10 bit then he'd recommend the DSOS over the RTM or RTA because it's more mature and performs better than the RS scopes.He also said forget about Tektronix MSO5 and MSO6, because they still are full of bugs and can't hold a candle to the DSOS. He also said Tek support is also not greatThen he said you should ignore the 6000X not only because it's just an 8 bit scope but also because despite it's high bandwidth it's just a simple scope with an embedded platform (blown up 4000X) and not anywhere near the performance class of the HDO or the DSOS despite costing (list price) almost as much. He also mentioned that apparently the 6000X sells so badly that KS had to give huge incentives to sell them.If you need 12bit then he the HDO4000A is a good choice. This is the successor model of your HDO4000He mentioned that Lecroy support has taken a bit of a nose dive after being moved from Switzerland to Germany (not as bad as Tek, though), and if they become problematic then usually talking to the U.S. support in New York will get things fixed quicklyHe also said that he hasn't seen many failures with the HDO4000 aside from dying hard drives. Replacing them with SSDs fixed the issue for good, though, and the failure you did describe might be easily be fixable for less than $50Hopefully this doesn't get me bannedand don'tthe messenger

author: tautech
author_rank: Super Contributor
timestamp: April 29, 2019, 09:23:17 pm
content: Quote from: Mr Nutts on April 29, 2019, 09:10:31 pmWhen we can't mention banned member Wuerstchenhund on this forum it will be a very sad day.It was bad enough he was banned rather than continue with robust debate and a guy that knew his stuff !

author: sdouble
author_rank: Frequent Contributor
timestamp: April 29, 2019, 11:01:26 pm
content: thanks for the update.I'll look at the DSOS054A, which may be a good option for me.

author: Keysight DanielBogdanoff
author_rank: Unknown
timestamp: April 29, 2019, 11:17:06 pm
content: The S is a good scopeRegarding bits of resolution, I'd encourage you to look at ENOB instead of just ADC bits.Not trying to threadjack on the 6000X, but it's a great scope for the price and is selling just fine. It's definitely limited in capability compared to the S-Series, but good luck finding a 6 GHz capable scope that's cheaper or smaller!