New Owon SDS1102 or used GW Instek GDS-1072B?

[robdejonge]

For a while now I've been looking at getting my first scope. Because I'm new, I figured I'd get an entry-level model to help me understand better what I want and in a few years get something nice. The entry-level ones I've been looking at are the Owon SDS1102 and the Hantek DSO2C10. Due to some reports of poor firmware and poor low-voltage measuring on the part of the Hantek, I've been leaning towards the Owon.

Then this morning I see a second-hand GW Instek GDS-1072B being offered for sale. From what I've gathered, this is a bulky but solid scope of a level superior to the Owon and Hantek. Seller says it's barely been used. Face design is per the site, not the one Dave reviewed five years ago. 

The price would be the same.

Before I pull the trigger, I thought I'd invoke the wrath of EEVblog forum by asking for thoughts on this decision.

(The seller lives quite close, so I would go to pick it up and be able to confirm it looks to be in good shape. Not sure how I'd be able to test it within the span of a few minutes, before handing over the cash?)

[Fungus]

The Instek is much better.

If you can get a good one for the same price as the others then go for it!

Not sure how I'd be able to test it within the span of a few minutes, before handing over the cash?

Power it on, hook up the test signal on both channels.

Twist the knobs, press the buttons.

[robdejonge]

Thanks very much for the reply.

I have no idea how to test this device in just a few minutes. There will be pressure to get it over with, as is normal and understandable. Hooking the probes to the compensation signal and change its frequency around a bit I can do, making sure the controls all respond I should be able to do as well (will see if there is a test screen for this).

Any other suggestions on how to validate its a good-working scope?

[kcbrown]

Thanks very much for the reply.

I have no idea how to test this device in just a few minutes. There will be pressure to get it over with, as is normal and understandable. Hooking the probes to the compensation signal and change its frequency around a bit I can do, making sure the controls all respond I should be able to do as well (will see if there is a test screen for this).

Any other suggestions on how to validate its a good-working scope?

There's not really much else you need to do with these things.  While it's possible that something's busted in one of the frontends that would cause it to not respond properly to higher frequencies, that's pretty unlikely.   If the scope is able to acquire and display the 1 KHz waveform from the calibration signal on both channels, then you're pretty unlikely to have problems with it.  The calibration signal is actually really good for this because it contains frequency content that spans much of the range of frequencies that the scope can handle.  On mine, for instance, the falling edge of the calibration signal, when the probes are properly compensated, will show a sharp corner in its transition from horizontal to vertical at even 50 ns/div.

The only other thing I can suggest is to have it run its self-calibration.  That should pass.  Have the seller turn on the scope something like 20 minutes before you get there so that it'll have time to stabilize internally.  If self-cal passes *and* it is able to properly display waveforms on the screen, and the UI is able to respond properly, etc., then the scope is pretty much good to go.  Any other issues that might take place (like the scope hanging or something) will be ones that you can't really test for anyway, and are unlikely to happen.

I'll second what Fungus said: the Instek is much better.   MUCH better.   It's no comparison.

[Electro Fan]

If it successfully self-cals and the probe compensation works you will probably be ok, or now might be a good time to quickly buy a function generator

If you happen to have a function generator or can borrow one you could take a BNC cable (or 2 if you have a 2 channel generator) and test frequencies other than 1kHz and maybe a few other things. 

Might depend like you indicated on how outgoing the seller is - but if the scope is working properly he shouldn’t mind too much you confirming that’s the case.  Be prepared to politely pass if the scope isn’t as it was represented.  If it was an old analog scope the check out process might be a bit of a coin flip but with a fairly recent modern scope you will probably be ok.

[robdejonge]

If it successfully self-cals

Pardon my ignorance here. In the manual I found a Signal Path Calibration and a Vertical Accuracy Calibration built into the device. I assume you mean the second of those two. I just trigger it as described and after completion it says "use an oscilloscope calibrator to verify amplitude".

I won't have one of those handy of course. And perhaps using the probe calibration signal (which does support variable frequency) here is a bit pointless, as (at the risk of sounding like an idiot here) it may somehow reference the calibration signal itself and thus always measure as accurate?

Appreciate your feedback! Thanks a lot.

[robdejonge]

If the scope is able to acquire and display the 1 KHz waveform from the calibration signal on both channels, then you're pretty unlikely to have problems with it. 

As per your suggestion, I'll announce to the seller that I will 'be running a few tests to make sure the device is in working order' so that he can decline and save me a trip. If he accepts, I'll ask him to turn the scope on ahead of my arrival.

I'm trying to figure out from the manual how to run the "self calibration test". See other comment.

Thanks a lot for your comment!

[kcbrown]

I'm trying to figure out from the manual how to run the "self calibration test". See other comment.

You'll need a known good 50 ohm BNC coaxial cable.  Self calibration is accomplished via the Utility button, then System -> Self Cal -> Vertical.  There's a "Cal Output" connector on the rear of the scope that is used by the scope to generate the signals necessary to calibrate the channels.  When you activate the calibration function, it will ask you to connect the cal output to channel 1 and to then press "Vertical".  It will then proceed with calibration of the channel.  It will display a progress bar as it proceeds.  When it completes, it'll ask you to connect the cal output to channel 2 and to again press "Vertical". 

The procedure is described on page 237 of the manual: https://www.gwinstek.com/en-GB/products/downloadSeriesDownNew/1681/135

On my GDS-1054b, the calibration procedure took about 10 minutes per channel.  Since the scope here is a 2 channel scope, this means you'd be looking at about 20 minutes, give or take, to complete the procedure.

That might be too long for you.  If it is, you can skip the second channel by not hooking up the channel when it asks and then pressing "Vertical", at which point it'll complain that it can't see the cal signal and tell you to disconnect the signal and press "Vertical".  While that would mean that you would have exercised only one of the channels, even that is enough to ensure that the acquisition system is functioning properly.

The vertical calibration procedure is a good way to make sure the channels are functioning properly, but if you don't have that kind of time, hooking up the probe calibration signal (on the front of the scope) via a probe at its 10X setting to each channel and examining the result on the screen is really good enough for this.  The signal is a 2V peak-peak signal that ranges from 0V to 2V, which makes it possible for you to exercise the channel's DC and AC settings, among other things.  And, of course, you can examine the corners of the probe calibration signal (the beginning of each edge, in particular) to make sure that the frequency response is good in the upper portion of the scope's frequency range.

The ideal, of course, is to bring an arbitrary waveform generator with you, but you don't strictly need one if all you're doing is making sure the scope functions.

[robdejonge]

Unfortunately, the seller was uncomfortable with me being a foreigner ("a lot of cheating") and so kept dragging his feet. In the end another buyer snatched it up right in front of my nose, literally a few hours before I was meant to meet the seller he texted me that it had been sold. Too bad, because I was quite excited about it.

But I wanted to thank you all for your comments and suggestions. I feel a lot better prepared for the next time an opportunity arises. As I said, this is my first scope and so a 'discount level' like the Owon might suffice. But perhaps I'll see another gem like this Instek available in the weeks ahead, and will jump on it.

Thank you all.

[kcbrown]

But I wanted to thank you all for your comments and suggestions. I feel a lot better prepared for the next time an opportunity arises. As I said, this is my first scope and so a 'discount level' like the Owon might suffice. But perhaps I'll see another gem like this Instek available in the weeks ahead, and will jump on it.

Bummer.

What are the prices of new Instek units like over there?

[robdejonge]

The GDS-1072b retails for US$600, tax included.

[kcbrown]

The GDS-1072b retails for US$600, tax included.

Wow, that's rather excessive.  Tequipment.net has that priced at $400.

Oddly, tequipment.net has better prices for the GDS-1202B and the GDS-1102B, at $320 and $280 respectively.  Both of those have more bandwidth than the 1072B.

And the 1054B (a 4 channel scope) is $345 from there.

These prices are pre-tax, of course.

What source would you have to use in order to acquire one of these?

[robdejonge]

I’m sorry, haven’t had coffee yet but I don’t understand the question? What source? Do you mean where would I have to buy them?? Sorry haha

[kcbrown]

I’m sorry, haven’t had coffee yet but I don’t understand the question? What source? Do you mean where would I have to buy them?? Sorry haha

Yep.  I'm curious what place is charging so much for these things.

[robdejonge]

I am Dutch but I live in Thailand. The $600 isn't even the highest price I've seen resellers here charge for the Instek.

While 'discount level' scopes (the ~$200 type) can be ordered from places like AliExpress and as such stand a decent chance of arriving without import duties added on top, 'entry level' scopes ($350-400 from respectable brands) are only imported but official distributors and import duties are always passed on to the consumer. This is why these things are so expensive here.

Electronics is a new hobby for me. I'm maybe two years in, have in recent months faced several situations where (according to a friend) a scope would have been useful to diagnose a problem and have decided I should be getting one. Because it's just a hobby, and because I really don't know what features are important to me, I don't really want to spend more then about $200 on one. For that budget, I can get a new discount level or a used entry level scope.

So how do I decide what to get? Well, my thinking is that accuracy is more important than bells and whistles. See, I don't know the first thing about scopes and I'll have plenty to learn even with a fairly basic scope. But when I see people posting videos of the Fnirsi 1014d not being able to read a 100MHz signal even if thats what it advertises, or a video of the Hantek DSO2C10 measuring low voltages incorrectly, this to me feels like a big red flag. Not because I need a 100MHz scope or expect many 100mV signals, but because I know this is an issue with these scopes I'll always be wondering if an odd reading is because of a lack of knowledge or because of a device not living up to its promise. I think when that starts happening, I'll stop using the scope and stop learning as a result. Not a desired outcome.

The Owon SDS1102 seems to be getting solid reviews and accurate results. So unless someone tells me otherwise, it's an option for me. The alternative would be something like the GW Instek, a second-hand, entry-level scope that still works well. Both available at a $200-250 price tag. The Owon would be on my bench within weeks. A second-hand would probably take months to source, because there is just not a lot of supply in the second-hand market. If "second-hand entry level" is the way to go, I'll muster the patience to wait for that. It won't be easy!

The way I look at this is that after I've mastered the features of this first purchase, I'll have a much better idea of what I want going forward. I'll know how many channels I should be getting because I kept running into the limit of having two, or not. I'll know if I need 100MHz, or if 50MHz or even 20MHz would have been fine. I'll know if a 10M memory depth per channel is awesome, or if I rarely ever use it. I'll know if a 5mV/div sucks, or is just fine for my predominently 3.3V domain. I'll know if 8 bits has regularly been annoying, or if its just fine. And once I know all those things, I can then splurge on a something of a higher quality with the features I need. Probably ditching my Salae-clone logic analyzer in the process, and integrating both into a mixed-domain device.

But hey, what do I know!? The above is what seems sensible to me. But I'm very open to being wrong. Would be very happy to get feedback!

Sorry, perhaps most of the above should be a separate thread?

[Fungus]

The way I look at this is that after I've mastered the features of this first purchase, I'll have a much better idea of what I want going forward. I'll know how many channels I should be getting because I kept running into the limit of having two, or not. I'll know if I need 100MHz, or if 50MHz or even 20MHz would have been fine. I'll know if a 10M memory depth per channel is awesome, or if I rarely ever use it. I'll know if a 5mV/div sucks, or is just fine for my predominently 3.3V domain. I'll know if 8 bits has regularly been annoying, or if its just fine. And once I know all those things, I can then splurge on a something of a higher quality with the features I need. Probably ditching my Salae-clone logic analyzer in the process, and integrating both into a mixed-domain device.

But hey, what do I know!? The above is what seems sensible to me.

You're posting in a forum full of people who already know all that stuff and are advising you not to buy the Owon.

Any oscilloscope is better than nothing at all, that's very true. Being able to see a signal is like day vs. night. If the Owon is really all you're able to afford, or you live in a place where other brands are much more expensive, then get the Owon.

(or even a $100 FNIRSI tablet!)

The difference between the Owon and (eg.) a Rigol is that even the cheapest Rigol might be all the oscilloscope you ever need for your entire life. The Owon almost certainly isn't.

[kcbrown]

OK, that's an excellent explanation of the situation.

What happens if you look for the various Instek 1000B series scopes on eBay?  I've no idea if you'd run into the same issues with acquiring one through those means, but it may be an option for you.

I think ultimately if it's a choice between no scope and the Owon, the Owon easily wins.  Presumably you can sell it later at whatever point you discover you want or need more.

[robdejonge]

The difference between the Owon and (eg.) a Rigol is that even the cheapest Rigol might be all the oscilloscope you ever need for your entire life. The Owon almost certainly isn't.

I think thats a fair point. So, I'll put you down for the "second-hand entry level" column then ;-)

Appreciate you sharing your thoughts.

[robdejonge]

I think ultimately if it's a choice between no scope and the Owon, the Owon easily wins.  Presumably you can sell it later at whatever point you discover you want or need more.

No scope is I think not an option anymore. It's really about deciding between the Owon and a second-hand entry-level scope.

What happens if you look for the various Instek 1000B series scopes on eBay?  I've no idea if you'd run into the same issues with acquiring one through those means, but it may be an option for you.

The same would apply. I'd incur high shipping costs and I'd end up paying import duties. Only way around those hefty duties is to have someone else (not me, as I live here) carry something over. An option, but at the moment not many people are planning on visiting! Beers are on me if you do! ;-)

All joking aside ... sounds like your view is "second-hand entry-level" over the Owon as well, and quite honestly, this is what my gut feel suggests too.

[kcbrown]

What happens if you look for the various Instek 1000B series scopes on eBay?  I've no idea if you'd run into the same issues with acquiring one through those means, but it may be an option for you.

The same would apply. I'd incur high shipping costs and I'd end up paying import duties. Only way around those hefty duties is to have someone else (not me, as I live here) carry something over. An option, but at the moment not many people are planning on visiting! Beers are on me if you do! ;-)

I don't understand how acquiring it through eBay would result in high shipping costs and import duties, while acquiring one through AliExpress wouldn't ...

All joking aside ... sounds like your view is "second-hand entry-level" over the Owon as well, and quite honestly, this is what my gut feel suggests too.

It depends entirely on the second-hand entry level scope.  If it's a Rigol DS1054Z or an Instek GDS-1000B series scope, then yeah, those are most certainly better.

So, a couple of additional questions.  Firstly, what's your actual budget here?  Apologies if you already mentioned it and I missed it (I did look back through this thread).   Secondly, what's your actual use case?

I ask because if you just need something cheap to learn with, just need to be able to see waveforms on the screen and perhaps use cursors, and don't need anything more than rising/falling edge triggers, then you can get something like the Owon HDS242S, which is a combination oscilloscope, multimeter, and waveform generator that is actually surprisingly good, and they're only about $140 or so on AliExpress (I told it that I'm in Thailand so as to see what the prices there are).  This also gets you the advantage of having an isolated reference on the input, so you don't have to worry about setting up ground loops when performing measurements.  I've got one of these and it's surprisingly fast, and may be all you need.  There are multiple videos about it on Youtube, and a dedicated thread here in the forum for it: https://www.eevblog.com/forum/testgear/owon-hds-200-handheld-oscilloscope-w-builtin-dmmawg/?all

The cheapest one (the HDS242, for $120) doesn't have a built-in waveform generator, but for an additional $20, it's hard to argue against getting the version (the HDS242S) with it.

Anyway, it's something to consider, particularly given your situation.  Because it has multiple functions, it'll be useful to you even if you do get a more capable scope later on.  And if you just need to be able to view waveforms with at most edge triggering, it may well be sufficient for your purposes.

[robdejonge]

Apologies for the rather slow response. I walked away from the thread convinced I should be looking for a second-hand entry level scope from a reputable brand. Dismissed the notion of spending $200 on an Owon or Hantek discount level scope and sort of settled in for what I expected would be a long period of checking listings every other day or so. This lasted a week ...

But first...

I don't understand how acquiring it through eBay would result in high shipping costs and import duties, while acquiring one through AliExpress wouldn't ...

Call it experience. Shipping fees can be ridiculous, just the other day I wanted to buy a $6 PCB and shipping would have been close to $50. Instead, I had it delivered to a friend in the UK for $6 shipping and he'll bring it over when he visits next. Import duties are very high in Thailand. For a scope, the official rate is 35%. But trust big-name carriers like UPS, DHL or FedEx to add on a whole bunch of 'handling fees' even if the seller states he'll pay all fees. I can think of many examples personally experienced, but won't bore you. Amazon pre-charges me for all this stuff, so I can decide if its worth it to me. Usually it is not.

AliExpress, and I couldn't tell you why, deliveries typically arrive without import duty claims. One seller I spoke to on this topic said to make sure I select EMS for shipping. His experience was that typically there would be no or very low duties.

So, a couple of additional questions.  Firstly, what's your actual budget here?  Apologies if you already mentioned it and I missed it (I did look back through this thread).   Secondly, what's your actual use case?

My initial budget was about $200. A first-time scope owner, the use case is blurry at best and this is why I didn't want to spend more money on it than that. The idea being that if I end up using it a lot, I'll be ok to invest into getting 'a proper one' down the road. For that money, a new 'discount level' Owon or a used 'entry level' GW Instek was the idea. A handheld scope might absolutely have been suitable.

However...

Less than a week after I missed out on that second-hand GW Instek GDS-1072b listed for $165 detailed earlier in this thread, another showed up for $120. Armed with the recommendations from this thread, I arranged for a video call with the seller and had him show me the probe calibration signal on two channels and push all the buttons on the front. He did not have a BNC to BNC cable to run the self-cal, but I felt comfortable enough to send him the cash and within hours received a tracking number from him.

Receive the scope yesterday. Let it come down to room temperature, turned it on, waited half an hour and ran the self-cal using a $2 cable I had laying around. It completed without incident, I confirmed again the probe calibration signal was acquired on both channels and pushed all the buttons to make sure it all works. It did!

So, for $120 it seems I now have a respectable scope with which I can start learning. It might be all I'll ever need. I may end up getting something beefier down the line. For now, I'm excited at having scored a great deal and gotten a new toy!

Appreciate your comments, thoughts and feedback throughout this thread. Thank you!

[Fungus]

$120 for a 1072B?

Winner, winner, chicken... etc.   

[robdejonge]

70MHz indeed
Leftover pizza for dinner though ;-)