Looking for a scope. - Page 1
Forum section: electronics / testgear

author: Davy
author_rank: Regular Contributor
timestamp: July 08, 2015, 01:52:43 pm
content: Hi, I'm looking for a 'scope'. I was looking at the Rigol D2102 100Mhz but was kinda' put off with loud fan and cracked knobs, I can't be doing with that so I thought of a DPO, a Digital Phosphor Oscilloscope and came across the GOS6103.Here's the data sheet from Farnellwww.farnell.com/datasheets/1759053.pdfI wonder your thoughts on this. My main interest is measuring RF say 50Mhz, I am aware of the -3dB bandwidth.... so I put everything on hold at the mo as I wanna be getting the right thing.The Rigol D2102 will display a 145Mhz clear signal and even display a 470Mhz signal although the sensitivity will by way, way down, another thing that worried me is the signal goes through a load of ADC's making the display anything but smooth.If you were getting a 100Mhz scope which one would it be as long as it got OSD graphics.Thanks, Dave

author: Fungus
author_rank: Super Contributor
timestamp: July 08, 2015, 02:16:25 pm
content: As measured/tested by EEVBLOG members: An unlocked DS1054Z can display signals up to about 120MHz with no attenuation.Do you want to pay more money for more features? That's up to you.PS: That performance is only on one or two channels. If you want 4 channels simultaneously you might want a 2000 series.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 08, 2015, 02:43:11 pm
content: Quote from: Davy on July 08, 2015, 01:52:43 pmRecently I was looking for a scope and searched both new and used offers. Used may be a good alternative, especially because you are interested in dealing with higher frequencies. Depending on where you are, eBay may be a good place: some finds I listed inthis postand some other models inthis other post.Quote from: Fungus on July 08, 2015, 02:16:25 pmFungus, Rigol's 2000 series only has two channels.

author: Davy
author_rank: Regular Contributor
timestamp: July 08, 2015, 04:27:37 pm
content: I don't like the idea of buying from Ebay, should it come to that I'd be better buying a refurbished one from a reputable dealer, to be honest I'd rather be dealing with the manufacturer or one of their agents.I do have a HP 1744 100Mhz storage.... but it's far too cumbersome and could do with a complete service, do have the service manual, I need a spare bench to work on it and can't be bothered taking that route yet.So a recap on my scope preference, must be 100Mhz at least, 2 channel input with OSD graphics. I do think I'm edging towards a DPO but undecided yet.Yep, I've seen Daves excellent videos..... never mentioned the fan noise or cracking knobs.... been reading on Keysight forum. one or two members come up with reducing the noise floor and giving their reps a hard time because they 'appear not to accept the fact' but that's a different kettle of fish.Dave

author: Fungus
author_rank: Super Contributor
timestamp: July 08, 2015, 04:33:48 pm
content: QuoteYou're right. My bad...

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 08, 2015, 04:42:53 pm
content: Quote from: Davy on July 08, 2015, 01:52:43 pmDPO is a marketing term of Tektronix, hence only Tektronix scopes will carry it.However, the GOS6103 is neither a Tektronix scope nor a digital scope, this is an analog scope. The type that was common some 30 (yes, thrirty!) years ago.QuoteIt's pretty poor, really. If it was still 1985 then I'd say it's a good buy, but in 2015 it simply isn't. Even less so at the $1300 Farnell wants for that blunder:http://www.newark.com/webapp/wcs/stores/servlet/Search?catalogId=15003&mfpn=GOS-6103&langId=-1&searchRef=SearchLookAhead&storeId=10194QuoteYou don't seem to understand the purpose of an oscilloscope, and no, it's not to make the signal look "smooth". It's an instrument to measure signal parameters, and for that you want the waveform as it really is an not "smoothened up". With this analog scope you will have very little in terms of measurements, and because it's analog it will often hide some signal components which you'll never see because what you see is what you get.Once upon a time an analog scope was a good starter scope, but (and I know the resident backwarders will probably jump on me) in 2015 that is no longer the case, and I'd would question the sanity of anyone who these days spends $1300 on a scope like this GOS-6103.If you want a decent entry level scope then there are several inexpensive DSOs that cost less than this analog boat anchor.But before you decide for a scope I'd say you have a fair bit of learning to do as I get the impression you don't really understand what you need, what the relevant parameters are when looking for a scope, and what the terminology actually means.

author: nctnico
author_rank: Super Contributor
timestamp: July 08, 2015, 05:28:50 pm
content: Quote from: Wuerstchenhund on July 08, 2015, 04:42:53 pmOr just start with a Rigol 1000Z series and go from there. At some point the shortcomings will make clear what to look for in the next scope. You have to start somewhere but I agree it would be unwise to spend money on an analog scope.

author: Davy
author_rank: Regular Contributor
timestamp: July 08, 2015, 06:15:12 pm
content: @ WuerstchenhundThanks for the input... I know it's not a 'true' digital scope where the signals passes ADC's, wonder where I got the DPO from...? I don't think I said it was a Tektronix.QuoteI know that too.Maybe you're right a DSO is the way to go...... but which one with 100Mhz 2 channel's. The price of a 'decent scope' you shouldn't have to worry about cracked control knobs and noisy fans, I've read several complaints here.Now, knowing about fake RF transistors from 'you know where', that's the reason I'm getting my doubts about getting a Rigol. From this you can deduce I wanna be ordering and having done without sending it back or getting on the phone.... what ever brand I prefer one from the manufacturers or their recommended agents.Back to drawing board I guess.Dave

author: Muxr
author_rank: Super Contributor
timestamp: July 08, 2015, 06:21:13 pm
content: Rigol's hardware is very good, I wouldn't be worried about the hardware with Rigol. The fan noise is exaggerated on here, my DS 2072A has audible fan noise but it's very muted and not annoying at all, and I am usually anal about fan noise. Their software can have issues on the other hand. However when it comes to bang per buck they are unmatched. This is because this great community has hacked these scopes.You can get a lowest end model in a series and unlock all the features fairly easily as if you bought the top model. This is why Rigol's DS 1054z and DS2072A are so popular. With the 1054z you get a 100Mhz 4 channel scope, and with the DS 2072A you get a 300Mhz 2 channel scope.At the low end you aren't going to find a better deal. If your budget permits then you can start looking at the modern scopes from Agilent/Keysight, LeCroy, Tektronix or Hameg.. but the cost grows exponentially with capabilities on these scopes.From your requirements it sounds like you would be happy with one of the Rigols mentioned.edit: watch Dave's videos as he's done teardowns on both of these scopes and see for yourself. Their hardware is pretty solid.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 08, 2015, 08:15:51 pm
content: Quote from: Davy on July 08, 2015, 04:27:37 pmTotally understand. Keep in mind that Keysight has aneBay storefor refurbished products. Rigol North America has aclearance binat their page.Quote from: Muxr on July 08, 2015, 06:21:13 pm100% agree with these statements. The fan noise irritability is something very personal.Quote from: Muxr on July 08, 2015, 06:21:13 pmIIRC the DS1000Z series has fixed bandwidth, only the options are hackable. Thus you would need a DS1104Z for 100MHz BW.

author: Davy
author_rank: Regular Contributor
timestamp: July 08, 2015, 08:17:49 pm
content: Thanks Muxr, yes I've seen the videos..... more than once, so much so, I'm back on the Rigol, still mulling here, be nice if I could see one at first hand that would allay my fears.Just that alarm bells rang when I read a couple of complaints about the fan noise and cracked control knobs elsewhere, especially after buying some RF power transistors from a so-called reputable source - 1mm too big they wouldn't fit in a Kenwood TS2000 HF transceiver, the die when X-rayed was about a third smaller, there were other tell tale signs too, hoping this might explain my dilemma.About the fan noise, the HP1744 has one I can hear that but would take it as normal .... not sounding like a 747 Jumbo on take off as one guy described the Rigol.Think I'll mull over Tektronix & Hameg as well, thanks all.Dave

author: Muxr
author_rank: Super Contributor
timestamp: July 08, 2015, 08:22:20 pm
content: I stand corrected on the bandwidth hack on the DS1000 series. Thanks rsjsouza! I have an HP 54610B and its fan is much louder than my Rigol DS 2072A. Actually that's probably going to be my next project. Replacing that fan.Good luck.

author: G0HZU
author_rank: Super Contributor
timestamp: July 08, 2015, 08:29:23 pm
content: 145MHz is a ham band so if you were planning to use a scope for monitoring typical old school narrowband ham modes then the best solution (IMO) is to have both a modern/new DSO that has a reasonable FFT mode and also an old/used analogue scope.I find that an analogue scope is much nicer to use when doing casual measurements of narrowband (AM or SSB) signals in the time domain.But the DSO is king when it comes to looking in the frequency domain using its FFT mode. The analogue scope can't do this. Even my old Tek TDS2012 DSO can display an FM signal at 50MHz and give an indication of the signal bandwidth and look for a Bessel null etc. Also, it can look at close in IMD levels on a classic narrowband two tone SSB signal at, say 50MHz. This isn't as good as using a dedicated spectrum analyser but with sympathy for its alias limitations you can get good use out of a basic DSO for typical ham radio tasks like this. Note: I actually exploit the alias limitations of the TDS2012 scope in order to do the above FFT measurements.So if you are looking at ham radio stuff then I would recommend you go for a DSO with a decent FFT mode that allows you to do the above stuff and (maybe) also try and pick up an old classic analogue scope for a cheap price. I don't think it's necessary to spend more than £50 on an analogue scope but I'd recommend getting one with at least 100MHz bandwidth if you do get one to go with the DSO.I have both analogue and digital scopes on my bench. The analogue scope doesn't get used much but it is still very nice to use for certain types of waveform and it can also do a few unique tricks that mean it still lives on my workbench 99% of the time.

author: G0HZU
author_rank: Super Contributor
timestamp: July 08, 2015, 10:06:45 pm
content: Here's an image of my old Tek DSO in FFT mode looking at a narrowband FM signal with a 1kHz test tone modulated at about 2.4kHz deviation. It shows a sharp Bessel null in the centre as expected.Also, the same signal is shown on an old HP8566B spectrum analyser and the two plots look very similar. I'm exploiting the poor alias performance of the TDS2012 in order to use it as a form of bandpass sampling downconverter to view the 50MHz signal as if it were an FM signal centred at a few kHz.This technique works well as long as it is used with a degree of caution and understanding of the scope's limitations.You can also do the same for AM or SSB modulated signals and get a reasonably good view of the signal bandwidth and any distortion terms in the frequency domain as you would see on a conventional spectrum analyser. You can't do this with an analogue scope.

author: tautech
author_rank: Super Contributor
timestamp: July 08, 2015, 10:27:17 pm
content: @DaveyA flag in your profile would help for local recommendations.You've had some sound advice and I'll add more for you to consider.The Siglent SDS2000 series has BW capabilities to ~320 MHz @ -3dB.http://www.siglentamerica.com/pdxx.aspx?id=25&T=2&tid=12 & 4 Ch models available.It has SPO that is Siglent's DPO.ATM there is a promotion running and depending on your location it's either for July or until September 30. Free BW upgrades and free options available.https://www.eevblog.com/forum/testgear/siglent-sds2000-oscilloscope-promotion-extension/msg706391/#msg706391

author: Lightages
author_rank: Unknown
timestamp: July 08, 2015, 10:42:09 pm
content: @tautech and rfloopIt would be interesting if one or both of you could make a direct comparison or opinion on the relative value of a DS1054Z and any of the Siglent scopes that you sell. I know I am putting you on the spot, as I have been with my advocating Brymen.I chose the Siglent SDG1025 because of its value and performance. I could have selected the Rigol equivalent and maybe would have been just as happy. It seems to me that the DS1054Z provides the best value in a low priced scope for the majority of prospective buyers in the class of beginner and even to advanced user. I would be happy to see how and why any Siglent in the same class could be considered a competitor or even a better buy.Sorry for the direct question, but I am not one to shy away from direct questions.Edit: I am interested in not just a comparison to the DS1054Z, but any comparable price range between the two brands.

author: tautech
author_rank: Super Contributor
timestamp: July 08, 2015, 11:16:21 pm
content: First the obviousSUPPORT400V rated channel inputs across the full Siglent DSO rangeBetter than 250Msa/s sampling with all channels driven.Vertical controls for each channel.Of course with a careful study of datasheets there will be winners and loser brands, but this presumes those looking for a scope know what to look for.This market is a very volatile scene, while one brand may have a very popular product it is a short time until other manufacturers are chasing them down. Look at the history of scopes from the 60's till now, it'll do your head in.To use an old saying: Every dog has it's day.History has proven this with all that man has made.To be fair one must compare apples with apples and as yet Siglent has no model spec'ed similar to 1054 and those that are are in a different class.Then there's the wish list:https://www.eevblog.com/forum/testgear/rigol-ds1000z-series-(ds1054z-ds1074z-ds1104z-and-s-models)-bugswish-list/Great thread, it puts the onus on a manufacturer to get their products right, in the end this sort of pressure means we all could/should benefit.I could mention the Siglent products in development but this helps no one looking for TE now./rant.

author: nctnico
author_rank: Super Contributor
timestamp: July 08, 2015, 11:48:16 pm
content: Quote from: tautech on July 08, 2015, 10:27:17 pmThe problem is that the firmware for the SDS2000 still isn't finished. A lot of functions are not working in a way that they are actually useful (FFT for example). Stupid me bought one and it has been sitting on a shelve for almost a year already. If a Rigol 1000Z isn't going to cut it better look at a scope from Keysight or maybe a Hameg even though it has a 640x480 screen if the budget is tight.

author: 0b01010011
author_rank: Regular Contributor
timestamp: July 09, 2015, 12:27:38 am
content: +1 for DS1054Z - a fantastic scope for the money and 4 channels - everything your average hobbyist would need.Have not regretted it at all and well worth the slightly extra over the DS1052.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: July 09, 2015, 01:09:45 am
content: Quote from: rsjsouza on July 08, 2015, 08:15:51 pmWrong. With the code DSER entered into the keygen and the key applied to the DS1054Z, the scope's "official" BW increases to 100MHz (bottom line on the Options>Installed screen display of installed options) and the "model" in the System Information screen becomes DS1104Z. Apparently several people have actually tested the BW and it really does increase.

author: rsjsouza
author_rank: Super Contributor
timestamp: July 09, 2015, 01:43:09 am
content: Quote from: alsetalokin4017 on July 09, 2015, 01:09:45 amThat is surely interesting to hear, alsetalokin4017.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: July 09, 2015, 07:19:17 am
content: Yes, and I think it's a major selling point for this scope.Apparently the 3dB rolloff point is even a bit higher than 100MHz. I can't test or confirm this myself as I haven't got an appropriate signal source that goes that high. But other forum members have tested and reported, in the long main DS1054Z thread.Below are the relevant screenshots from my DS1054Z: