Help choosing an ARB: New Siglent SDG1020 vs Used Fluke 281 / Wavetek 39A - Page 1
Forum section: electronics / general

author: tramjoe
author_rank: Regular Contributor
timestamp: August 02, 2012, 11:22:47 am
content: Hi all,I am in the market for a lab function generator, and my needs are very basic for now: resonate a few circuits, test inductance, test basic filters, etc.After comparing the low cost options (siglent / atten / rigol), it seems that the Atten is crap and the Rigol has a characteristics a bit below the Siglent. BTW, please, oh please, could the couple of people (yes, you know who you are) who keep ranting about Siglen being Atten, SDG1020 being the same crap as the Atten one, etc. refrain from polluting that post ?Anyhow, for a new, low cost option, I had my mind set on the Siglent.However, I can obtain a used WaveTek 39A, which is also sold as the Fluke 281, for the same price shipped as the Siglent unit.On paper, the Siglent is ahead: 20Mhz vs 16Mhz (max, of course, per signal form varies), 12 vs 14 bits, 2 channels vs only one channel on the WaveTek, more signal modulation options on the Siglent, graphic display vs 4x20 LCD, etc.However, I tend to think that the WaveTek would be far ahead in terms of accuracy and stability (has been recalibrated by Agilent in 2008 too), including drift over long-time periods. But I cannot find any review on the internet, all I have are the specs.What do you guys think ? Any advice regarding going for one or the other ? Any feedback or guessing about the Wavetek / Fluke superior quality / accuracy / stability ?For reference, here are both datasheets and pictures:WaveTek / Fluke:Picture with Fluke brandPicture with WaveTek brandDatasheetSiglent:EEVBlog thread on the SiglentPicture (of the similar 25Mhz model)Datasheet (what passes for one at least)Thanks for reading this, I could really use some informed commentsBest,--Jerome

author: nctnico
author_rank: Super Contributor
timestamp: August 02, 2012, 12:01:31 pm
content: I have been looking around as well. The Siglent SDG1000 series is hard to beat pricewise especially because of the dual output. A lot of the older units also have very bad user interfaces. I recall using the older Agilent generators (the ones with the VFD display) and they where not easy to adjust quickly. Unless something interesting turns up on Ebay I'll buy a Siglent.

author: jeremy
author_rank: Super Contributor
timestamp: August 02, 2012, 12:08:50 pm
content: Hi mate,It's only partially related, but I thought I'd chime in anyway. I have a Rigol DG1022 for home use, but I use Tek arbs regularly. Call me naive, but I really haven't found too much of a qualitative difference in accuracy (I have never tried to measure it, but it has never become a problem). I especially have found the 2ch useful as you can phase align then offset the two channels (and I love the built in ECG waveform). Sometimes I have taken my rigol in just because I wanted the two channels. Also, 40MS/s seems pretty sad, my rigol has 250MS/s on CH1 iirc, beats me how they get 16MHz out of it at just a touch under the nyquist.The real question is, what are you using it for specifically ? Is long term drift really important to you, or do you just want to push some sine waves through a some coils (like you mentioned earlier)? If the latter, I would just go with the siglent.One caveat: the wavetek might be easier to repair, but if it is DDS I doubt it. I've never looked inside any wavetek gear though.good luck!

author: T4P
author_rank: Super Contributor
timestamp: August 02, 2012, 01:06:18 pm
content: The last time something was called wavetek was a LONG time ago ...I have a wavetek meter ( i picked it up for free! But it's so basic you wouldn't believe me ... )that is like 20 years old at least ...

author: tramjoe
author_rank: Regular Contributor
timestamp: August 02, 2012, 01:53:55 pm
content: Well, already some interesting comments. Thanks guys.To clarify, yeah, I will just need to "push some sine waves through a some coils" Jeremy, at least for now :-)In any case I must say I am surprised by your replies, I was sort of expecting the other trend from forum advice. Somehow, however, I think this matches what I am tempted to do (go for the Siglent), but am scared to do because of those so many "these cheap ARBs are PoS" comments floating around. So a 1500€ piece of kit (that's what those units retail for when refurbished at mainline shops around here) for less than 300€, a.k.a. the same price as the Siglent, seemed somehow tempting even with the lower specs.I'll wait a bit more for other experienced voices to be heard here, time for me to turn my money in my pocket a thousand times before buying anything ;-)

author: T4P
author_rank: Super Contributor
timestamp: August 02, 2012, 02:21:02 pm
content: As shown, siglent isn't cheap POS, it's actually quite good

author: aghp
author_rank: Regular Contributor
timestamp: August 03, 2012, 07:02:58 am
content: Quote from: jeremy on August 02, 2012, 12:08:50 pmReally? You have some special model?Rigol DG1022 and 1022AQuoteSiglent have 2 fully independent channel. Both channels have 14bit vertical resolution.Arb memory is tiny but still far more (16k) than Rigol.125MSa/s. Difference between channels is only output amplifier. Output signal level is reduced in CH2.Building quality is good.There are 5MHz to 50MHz models in same SDG1000 series.Signal quality is also good.Something about it here.Some information can find alsoherebut this is partially only local language this time and this time only small amount of information. Later more lab grade tests.Manuals and datasheets can find also here.In most places Siglent pictures are from OLD FW. (example display colors are lot of different and it is not anymore "candy store" )

author: tramjoe
author_rank: Regular Contributor
timestamp: August 03, 2012, 09:30:51 am
content: @aghp Thanks for all the great additional info.I guess that puts the last nail in the coffin for the used WaveTek then. Siglent SDG1000 series it will be :-) Price/perfs sweet spot for me seems to be for the 20Mhz one, so I guess I'll order that.

author: pauln
author_rank: Contributor
timestamp: August 06, 2012, 09:42:13 pm
content: Quote from: tramjoe on August 03, 2012, 09:30:51 amI have had my sdg1020 for about a week. So far so good. I have found/stumbled across a software/firmware bug - when using dbm units of measurement if you enter 1dbm the unit displays 1000dbm, if you reduce amplitude a little you get i.e. 980dbm and so on. So I connected to my CRO and the amplitude is 1dbm, 0.980dbm etc. So the levels are OK but the Siglent display says something else. Yes I have tried the different numeral display formats.I emailed Siglent here is part of reply. "I have to say the what you said is our software bug. Can you use Vpp to replace it? "Have asked when they will sort the problem - no reply so far. If other users have same bug perhaps they can email Siglent to speed them up.

author: aghp
author_rank: Regular Contributor
timestamp: August 06, 2012, 11:06:08 pm
content: Quote from: pauln on August 06, 2012, 09:42:13 pmWhat is your FW?Siglent know this problem very well - I think they have get several reports about is and perhaps not only from peoples who have Siglent. Between -1dBm to 1dBm there is red class bug if use dBm.I'm glad to hear if some expensive LC WaveStations have these same bugs.Of course there come later new FW, just as before. It need come. There have been updates and no one think they just have stopped meke new updates.There is also some other bugs. Some are "cosmetic" level bugs but some are also littlebit higher level bugs. Example, if you set External frequency reference and select SDG remember las state. This selection it forget but if look meny, it is still selected. This is bad becouse there is no any information in the display that it use ext ref or internal. So, if you believe it is extrernal, becouse you have selected it and menu also show it is selected.. and equipment have changed to use internal if power have been off. It is not nice. With it can live if know this but it need repair as soon as possible.Also, but this is not exatly bug but it is not so nice how cursor jump between decads and n some cases not. I think it can be more user friendly. Programmer need better think what people is doing when he example change frequency using this knob. Also it works now and after short experience it is easy use and thanks <- and -> buttons are usable with same hand easy what turn knob.Also there is missing feature. Least I miss it. I like if there is selection that I can connect together channels frequency so that in this mode both channels follow same freq. (but this is more in class: I like this but not this..)In practice It need collect some "basket" about bugs what need repair exept if there is really fatal class bug. It is maybe not so clever do every bug separately.Last FW what I have used have last two digits .23.I have meet three different FW's (not remember this first FW number now but with very very bad TFT contrast and then .20 and now .23)

author: LaurenceW
author_rank: Frequent Contributor
timestamp: August 06, 2012, 11:17:09 pm
content: Another vote here for theRigol DG1022from me. I don't think the 1022A variant is actually "out there" - Could just be a spoiler from Rigol Marketing.I did consider the Siglent, but that colour display just seemed a little bit too "bling" for my tastes. The Rigol DG1022 is a solid little performer, and does what it says on the tin (as best I am able to measure it). It is intuitive in use, and personally I haven't caught it out yet. Rigol have not seen the need to release any software upgrades for this generator, that I can see. The ramp/triangle waveform only goes up to 150kHz which may seem lower than some competitors, and this MIGHT impact some people's choice (not mine).OH - and it contains NO (0) fans! Silent, silent, silent.The Rigol is not alone in offering this, but I do find that DUAL outputs are more useful than I might have thought. Older second hand budget kit wont feature this option very much.At these prices, be prepared to be disappointed with most brands when it comes to the PC control software, and some "extra functions" like built in frequency counters; these may work if you've got no other dedicated counters/times, but their spec is usually limited.

author: pauln
author_rank: Contributor
timestamp: August 06, 2012, 11:22:42 pm
content: Quote from: aghp on August 06, 2012, 11:06:08 pm

author: jeremy
author_rank: Super Contributor
timestamp: August 07, 2012, 12:34:00 am
content: Yes, my bad. It is only 100Meg samples. But I still like it very much and USB control via the USB-tmc class is absolutely fantastic.

author: aghp
author_rank: Regular Contributor
timestamp: August 07, 2012, 08:54:42 am
content: Quote from: jeremy on August 07, 2012, 12:34:00 amAlso:SDG1000 series can be controlled using either USB-GPIB orUSBTMCprotocols.USBTMC: Utility --> IO Setup --> USB Setup --> USBTMC.

author: tramjoe
author_rank: Regular Contributor
timestamp: August 14, 2012, 12:35:35 pm
content: Update and question: I finally bought an SDG1020, received it today.However, I am experiencing overshoot in square mode that far exeeds the quote ranges in the SDG1000 docs. Depending on the spec sheet source/version, it is supposed to have anywhere between <3% overshoot to "5% typical at 1kHz / 1Vpp" (hereandhere), the current Siglentdatasheetquoting the <5%(typical,1kHz,1Vpp) value. Apparently this has changed/been updated over time in the docs, and the "typical" quote is not a guarantee at all, that I understand.However, I am getting anywhere between 8% to 10% overshoot - depending on how I measure it - from 1kHz to 20MHz in square mode, Vpp not being really a factor there. Funny thing is that this is on CH1, on CH2 I get a little less (6% to 8%).Could those of you with an SDG1000 series ARB tell me what overshoot value they are getting for square waves ? I am measuring this on my Owon SDG7102 scope, tried different probes, in 1x and 10x modes, recalibrated my probes, tried BNC-to-BNC cables directly too, etc. My own measurement are on par with the scope auto-measure (well, within 1% or so usually).WDYT ?

author: nctnico
author_rank: Super Contributor
timestamp: August 14, 2012, 04:06:46 pm
content: What is the bandwidth of your scope?

author: aghp
author_rank: Regular Contributor
timestamp: August 14, 2012, 04:14:33 pm
content: SDG Specification means BNC output directly. All what you connect there affect and produce more or less. It is good to know that measurement change device under test. After connect something, circuit is different. Allways.Here some self explanating simple tests.Used OWON SDS7102V becouse question was what Owon show.(This (individual unit) Owon have around >270MHz -3dB BW and risetime around 1.3ns.)Generator under test: Siglent SDG1025 (HW: 0F-00-00-19-23)Due to lack of time used only Siglent CH1 and short form trivial test.In case "ProbeGNDwire" it means Owon T5100 probe center tip is inserted to SDG output BNC center and GND wire is connected to this same BNC ground (most bad what ever can do). In some picture there is extended GND wire. Probe black GND wire is extended with around 30cm wire.50 ohm line means that there is M17/084 coaxial and TEK 011-0049-01 terminator.Probe adapter means BNC adapter where probe tip can connect and also it makes GND connection directly to probe around center tip. (Probe GND wire is useless in this case.)SDG Square risetime is roughly around 6ns. Measuring this kind of signal need take care about signal impedance matching - not critical but as it can see so small wire as Probe GND wire make lot of problems. Also it need remember, oscilloscope input have roughly around 15pF and probe tip more, this GND wire is inductance. Also oscilloscope input with terminator is NOT 50 ohm impedance example with 50 or 100MHz frequency.Then there is 10Hz Square and used probe GND wire + 30cm. Who think 10Hz square wave need go using impedance matching. What if risetime is 1ns or less.This is why it need nearly always think as making measurements. How my measurement change what I am measuring. What kind of error source it is, how my measurement change device under test or signal under test.Mostly this kind of questions are widely underestimated.Last there is example with 1Hz Square... there can also see this ringing - overshoots even if whole cycle is on the display.(scope Aqc mode is peak detect)And note, also all my tests are littlebit wrong, becouse also my measurement affect some.Scope input attenuator/ampliffiers are not at all perfect. There is reactive load after SDG... and so on.

author: tramjoe
author_rank: Regular Contributor
timestamp: August 14, 2012, 10:20:47 pm
content: @nctnico c.f. aghp post - 100Mhz - 1GSa/s@aghp Thanks a lot for taking the time to do those measurements.From what I see here, my unit is in the same ballpark, so I guess it behaves normally. I tested it again this afternoon, this time replacing the Owon factory probes by 250Mhz probes. The results are much better, both when connecting the probes directly to BNC (unfortunately no BNC attachment on those, so probe pin stuck in BNC center plug and croc GND on the BNC chassis) or using a BNC to 4mm adapter.However, I wonder how artificial the results might be, as those probes have 3 pots for calibration. The pot on the probe is similar to the Owon probes' pot, but the two others on the BNC plug attachment which affect overshoot the most only have an effect at higher frequency (in the Mhzs range, not Khz), so I cannot calibrate those properly from the Owon reference signal and cannot be sure that I am not "cleaning up" the Siglent's signal with badly calibrated probes :-( So my good measurements (2% typical overshoot) are dubious at best.Any advise on how to calibrate those probes properly on the cheap ? Obviously, I do not trust _yet_ the Siglent ARB, so I cannot use it for that purpose ;-) Chicken-and-egg problem there. What is the cheapest ~5Mhz square signal reference I could buy/build ?

author: kingjay1
author_rank: Newbie
timestamp: August 15, 2012, 03:50:16 am
content: Quote from: aghp on August 07, 2012, 08:54:42 amI tested the USBTMC,and it's OK.I send a email to siglent for SCPI command which I can used to control with NI-VISA.

author: aghp
author_rank: Regular Contributor
timestamp: August 15, 2012, 05:36:08 am
content: SDG Programming manual is not in your CD?(also you find it from LeCroy but there may be some diference - or not))

author: kingjay1
author_rank: Newbie
timestamp: August 15, 2012, 06:14:23 am
content: Quote from: aghp on August 15, 2012, 05:36:08 amNo,I didn't find the programming manual in CD.I only know something about siglent and atten.Their digital is only the same just changed the model.But their waveform generator is really different.The SDG is much better than ATF.I don't know atten why not choice siglent again.

author: aghp
author_rank: Regular Contributor
timestamp: August 15, 2012, 11:06:26 am
content: You have message (PM)