Owon SDS7102 or Tektronix TBS1062 or TDS1002

[luca1000]

OK, I don't know if this question can be ask or there is no response:

If I compare a Tek 2445 and a Rigol DS2072.

I like to known, if possible,

1) what is the scope with a better dynamic range.
2) what is the scope with lower noise.
3) what is the scope with best channel separation.
4) What is the scope with less jitter.

[Hydrawerk]

http://www.pa4tim.nl/wp-content/uploads/2010/11/1n4148.png
This doesn't look like a printscreen from a DS1000 scope... What's that??

[jpb]

But nice question:
What is yours DSO bandwidth calculated by 1/2 x sampling speed if you turn it to 50ms/div.

Tektronix 2465B have 400MHz simultaneously for 4 channel using 50ms/div horizontal speed.
Owon SDS7102 have 2.5MHz.  for two channel
Rigol DS1000E have  ~437kHz for two channel
Hantek DSO500B HW1005 have 250kHz for two channel (40ms/div).
Siglent SDS1000xxL have 250kHz only for two channel.
How much Agilent 9000 infiniium have, I do not know.

Now in cheap DSO if there is any frequency componet over this bandwidth it produce total false informations. Of course if you know your signal... but if you know your signal why you need oscilloscope. Only for fun playing?

With DSO you have 1Gsa/s but only in some cases.  But analog old work horse is always 400MHz.  And even with 800MHz included to signal under test it do not produce any alias (btw, how you know really that alias is alias or if your signal have it really what you see on the screen?
Sinewaves are still easy but complex signals may have lot of freq components and when you look it with DSO you really do not know exactly sure anything if there is aliasing.

In true it is perhaps example 50sa/s to 1GSa/s dependent your horizontal speed.

This is interesting but it is not really fair on modern DSOs. 50ms/div is very slow - implies that you're looking at signals down to about 2Hz (one wavelength in 0.5 secs). Also if you use peak-detect high frequency noise would show up as the sampling rate will be 1GS/s, the points just won't be stored.

If something then looks odd, you'd presumably go to a faster time base and the sampling rate would rise.

[nctnico]

Tektronix 2465B have 400MHz simultaneously for 4 channel using 50ms/div horizontal speed.
Owon SDS7102 have 2.5MHz.  for two channel
Rigol DS1000E have  ~437kHz for two channel
Hantek DSO500B HW1005 have 250kHz for two channel (40ms/div).
Siglent SDS1000xxL have 250kHz only for two channel.
How much Agilent 9000 infiniium have, I do not know.

Now in cheap DSO if there is any frequency componet over this bandwidth it produce total false informations. Of course if you know your signal... but if you know your signal why you need oscilloscope. Only for fun playing?

Like I said. No grasp of sampling theory. The book you link to are just some random ramblings (*). Tektronix has published some real books on how to design an oscilloscope (and other equipment). You better read that because those where written by people who actually build test equipment!

Anyway, a key feature of a DSO is peak detect or envelope mode which makes the samplerate irrelevant. Peak detect basically does what an analog scope does only much better. Even extremely short pulses which are invisible on an analog scope (with the same bandwidth) are visible on a DSO. If you need to clean up a signal you can change the acquisition mode to sample mode, average or high resolution. Try to do that with an analog scope....

(*) After reading the first line of the book you know the truth is where the money came from:
After ten years from its first edition this handbook needed updating. HAMEG Instruments GmbH, a major manufacturer of both Combiscopes and analog scopes a subsidiary of Rohde & Schwarz, sponsored this second edition.
Just skipping through it I already spotted lots of errors like you'd need the samplerate to be at least 10 times the bandwidth. Utter nonsense and shows the author clearly has no clue about the difference between sampling a signal and displaying a signal.

Another snippet where the author admits he doesn't now what he is writing about:
it is not possible to truly judge DPO’s, this would require an extensive test.
Without scientific evidence any claim is a mere opinion.

[nctnico]

for most the no-brain button (auto) 

Which is also available on every analog scope made after approx. 1990 as well. Never used it though.

[PA4TIM]

That was my 900 euro down the drain Rigol DS1102e .But Trr are no easy measurements. For most standard  measurements it was usable.  A year later or so they dropped the price by 40% or so, after everybody started upgrading the 1052

This is a normal measurement.

.

If I compare a Tek 2445 and a Rigol DS2072.

I like to known, if possible,

1) what is the scope with a better dynamic range.
2) what is the scope with lower noise.
3) what is the scope with best channel separation.
4) What is the scope with less jitter.

1) Do you mean min/max input ?
Tek=  800Vpp AC upto 10 kHz and 400VDC+AC for the whole frequency range (straight at 1 M input)
Rigol: CAT I 300 Vrms, CAT II 100 Vrms

2) do not know but probably the Tek, at least I, never had noise problems with that.

3) 2445 = 100:1   That is 40 dB if I'm right
Rigol = 40 dB too
4) 2445 less then 100 ps at 150 MHz and I read somewhere here +/- 200ps on the Rigol

Anyway, a key feature of a DSO is peak detect or envelope mode which makes the samplerate irrelevant. Peak detect basically does what an analog scope does only much better. Even extremely short pulses which are invisible on an analog scope (with the same bandwidth) are visible on a DSO. If you need to clean up a signal you can change the acquisition mode to sample mode, average or high resolution. Try to do that with an analog scope....

But that extreme short pulse must  occure  in the extreme short time the scope is realy measuring instead of doing other things. I had a problem with runts while repairing a Fluke 8500. It drove me nuts. Nothing to see on the Rigol. Thenm I took the 7704 and I noticed some flashes now and then. Then using the whole arsenal of tricks the DSO was usefull because now I knew what to look for and after a lot of hassel I could capture it. ( but to be fair, the flashes on 7704 gave me enough info. Repairing a sat tuner I had a nice ripple on my Hameg, so all looked OK, but it was not. I hooked up my 7603 and I noticed a dip flashing buy every now and then. Like once in 10 or 20 seconds. Turned out a cap was shorting for a very short time at that moment. After that I could find it on the Hameg to, but like Bob Pease once said, if I know the signal I do not need a scope.

That guy designed scopes and I know it is hard to believe with a brainwashed digital mind but he is not telling nonsens. Most  good Tek books are even older, the later once from the digital area tell you only what you want to hear....

Are you serious ? Never seen real auto on analog scopes but I have no analog scopes from after 1990. But does that set timebase, trigger and V/div and on a real analog scope. ? I'm curious, never knew this, please name a model.

 Auto as I know on an analog scope is only autotrigger to get a trace. Even my 1966 453 has it. But that is not a bad thing.

[rf-loop]

Never seen real auto on analog scopes but I have no analog scopes from after 1990. But does that set timebase, trigger and V/div and on a real analog scope. ? I'm curious, never knew this, please name a model.

Something example like this, Tektronix 2445B, 2455B, 2465B
In manual there is more explanations.

Just push AUTO on scope front panel or button in probe.

[PA4TIM]

http://www.pa4tim.nl/wp-content/uploads/2010/11/tekgewoon.jpg this was my 2445, that had no auto button (as far as I can see). Never knew the 2445B was besides a bigger bandwidth so much different on other things too. Nice, thanks for the info.

[luca1000]

This 2445 or similar have a particular very good fashion !!

Seem the Top on the Top and this can be pay only some few euros !!!!

I don't understand WHY the people (and I include me in this list) was think to choose a cheap low end chinese (that sometimes cost more) scope and not this jewel of performace ? just when you listening the tick of a knob (like time base) seems to be something truly superior regardless !!!!

[rf-loop]

http://www.pa4tim.nl/wp-content/uploads/2010/11/tekgewoon.jpg this was my 2445, that had no auto button (as far as I can see). Never knew the 2445B was besides a bigger bandwidth so much different on other things too. Nice, thanks for the info.

Yes, this 2445 (without A or B) version do not have. Also internal  is totally different in more new veresion of 2445.
Last versions of 2445B have (afaik) 200MHz BW. (and there may still be 150MHz label on front panel, it need somehow look serial number but I do not know exactly what time this change was. But If I remember right there is also 2445B where front panel text is 200MHz. )

[nctnico]

Are you serious ? Never seen real auto on analog scopes but I have no analog scopes from after 1990. But does that set timebase, trigger and V/div and on a real analog scope. ? I'm curious, never knew this, please name a model.

The Tektronix 2400 series has it. On this Tek 2445A the button is right to the top of the screen:

[PA4TIM]

RF-loop, i once read there was something with a bandlimmit filter. Do not recall the precise types but if you remove that filter you get the higher bandwidth. That way some eby dealers rebuild 2445B models to 2465 or 2445A to B models ( can not recall that, it is domewhere in the Tekscopes group archive)
Some sold the scope as 200 MHz but still with the old graticul front, do the state a different BW.
To bad it also happns the way around, they sell a 2445A with the B front. And some mod the 2445A ino a B and also exchange front. So you think you buy a real 2445B ( types are just an exale because, like I said, I can not remember the excact types) but be carefull.

I had a beatifull 2445. That was realy spot on. But then I bought the Rigol, had a few 7000 scopes and a few 5XX ( and some more, and not enough space) so I gave the 2445 away.  After some time with the Rigol I really started missing it. It was allmost absurt accurate. But the Hameg filled that gap good enough. My 7704 has the fast puls response option so it's Tr is faster. 7000 are realy great scopes, in size and performance. To bad they are not as mechanical solid as the 24XX serie. ( very flimsy buttons and the plugin latch system is a joke, as is the powerbutton mechanism, changing lightbulbs is a nightmare)

[Wuerstchenhund]

I don't understand WHY the people (and I include me in this list) was think to choose a cheap low end chinese (that sometimes cost more) scope and not this jewel of performace ?

I can of course only speak for myself (and I never bought low end scopes until last week, and even this is more of a 'throw away' scope and not my primary scope), but instantly the problem for me would be the very limited signal analysis capabilities (no math, no FFT), no proper storage, no segmented memory, no way to capture waveform data and transfer them onto a computer etc. Plus it's very big, and likely approaching the end of its lifetime.

A new low end scope is at least new (and usually comes with warranty), takes much less space and consumes less energy. It also offers much more measurement functionality, and allows you to capture (and externally analyze) waveform data. On some of them (like the very cheap Siglent SDG1102CNL I bought as a 'throw away' scope last week) you can even use the captured waveform data as input for an AWG (Arbitrary Waveform Generator) which then 'plays back' the captured signal. This can be great for takeing a 'sample' from a real-life signal which then can be used as simulation in your lab.

If all you want to do is being able to look at some waveforms then all this doesn't matter of course, and if you can get a decent analog scope for little money then why not? But I would not recommend investing much money in a scope which is a) very old and b) where you might quickly outgrow it's very limited capabilities.

just when you listening the tick of a knob (like time base) seems to be something truly superior regardless !!!!

Indeed, many of these old scopes demonstrate a very high build quality and workmanship. But at the end of the day the question is what you want to use a scope for (as a collector's item or a tool).

I'm certainly not against analog scopes in general (I've used them long enough myself), but the fact remains that, outside any nostalgic dwelling in the past, analog scopes are dead technology, and this for very good reasons. Despite DSOs occasionally being bad-mouthed by some oldtimers that are essentially stuck in the past or never learned to handle a DSO properly, the simple fact is that you can go into any high tech lab around the world which works with highly complex and sophisticated signals, and you will only find DSOs there (and believe me, had analog scopes any advantages that are still relevant then they would still be used there). Of course DSOs do have their limitations, but that is equally true for any test instrument. If you don't understand these limitations you're f'ed, no matter if its digital or analog.

But the truth is that the capabilities of analog scopes are very limited and that the majority has long past its zenith in terms of life time, which means that you may up ending with a scope which quickly becomes a project in itself instead of a tool you can just use for getting on with your projects. A scope project is not necessarily a bad thing if you're looking for this sort of projects (there are many people restoring old analog scopes which is great) or if you're at least prepared for that. I'm not sure this is the best thing for a beginner, though.

[rf-loop]

RF-loop, i once read there was something with a bandlimmit filter. Do not recall the precise types but if you remove that filter you get the higher bandwidth. That way some eby dealers rebuild 2445B models to 2465 or 2445A to B models ( can not recall that, it is domewhere in the Tekscopes group archive)
Some sold the scope as 200 MHz but still with the old graticul front, do the state a different BW.
To bad it also happns the way around, they sell a 2445A with the B front. And some mod the 2445A ino a B and also exchange front. So you think you buy a real 2445B ( types are just an exale because, like I said, I can not remember the excact types) but be carefull.

I had a beatifull 2445. That was realy spot on. But then I bought the Rigol, had a few 7000 scopes and a few 5XX ( and some more, and not enough space) so I gave the 2445 away.  After some time with the Rigol I really started missing it. It was allmost absurt accurate. But the Hameg filled that gap good enough. My 7704 has the fast puls response option so it's Tr is faster. 7000 are realy great scopes, in size and performance. To bad they are not as mechanical solid as the 24XX serie. ( very flimsy buttons and the plugin latch system is a joke, as is the powerbutton mechanism, changing lightbulbs is a nightmare)

What 2445 models I have owned they are mainly from original user and all they have been "untouched" and if there have been service before me, all have done they own lab or tektronix lab. Also before me they all have been in cyclic unbreaked calibration whole they life until sold out as surplus.  Still have some 2445, 2445A and (2445B not exactly sure becouse time ago I sold some these),  2465, 2465A-DM and 2465B etc.

I know 7000 also becouse I have some these. Perhaps most nice is one true double beam unit, and then one  400MHz with storage and one 7854 with signal digitizing including 7854 waveform calculator keyboard. etc. And then some more usual models.  These are not anymore in active use, just stored. But sometimes I run these for keep then alive.

[rf-loop]

Also there is one aspect.

If someone want make example new Tektronix 2465B with CT opions etc.
Its price is - more than high. I can not imagine how extremely high it is. Then can ask, who want buy them. With this aspect, of course world of high class analog oscilloscopes is dead.

Professionals and higher level hobbyists know limits of digital and analog oscilloscope also. Specially low end digital oscilloscope user NEED know his equipment for avoid troubles.

What I'm some amount worry is entry level hobbyists who do not know enough and then he can not understand why and what this digital scope show. Then is lot of talking that is this normal or fail and why it so like this and so on.  For good acceptable results with unknown signal there need understand and know how these work and how to avoid false. Aliasing is one thing what really need understand and understand how oscilloscope relly work with different settings and what it may do with unknown signals. Example slow horizontal speed, low samplerate but still analog front BW fully open.  Samplerate 1MSa/s but front end open so that all from 0 to 300MHz can go to ADC... then wonder what hell is on my display and what is my real signal under test and what information is just garbage. Then ask, is this my scope bad or do it have some fail. How this crap can sell and who repair this my scope.

Shortly, for many peoples. Know your equipment, know basic fundamentals. It need learning work but is is only way to get other than just false measurements. With analog scope it is more "safe" and these traps which can drop is less.

(about Siglent, yes, in its price class ok for many use and many nice features and building quality very good in its price class and acceptable if do not take price to count...and even protective real glass front of TFT hehe... wait a moment after I get SDG5000 for tests)

[luca1000]

I'am not an expert (I understand only about audio D/A converter that is different).

But for my opion the REAL limit of these digital scope is resolution (8 bit 256 point are not enough).

When I see a sine signal on the analog like 2445 I see a VERY perfections , no any defects about the scope, only the defect of the signal (if there are).

When I see on digital scope (expecially on cheap scope, but not only) I see only some points and the result is not accurate.

Ex: on a screen of 800x600 (256 points are not suffcient to fill 600 points and interpolations or other is a compromise). And apart this, 1 G sample is another compromise that cause inperefect result.

In short if you want Quality and accurate result (>10 Hz, periodic signal) I think no way better then analogue you can find.

when I see  a periodic signal (>10 Hz and < 50 Mhz) the result of a analogue 2445 is a REAL result, but with a digital scope < 700 Euro the result can be false and in all case is a compromise (some points no perfect reconstructions like analogue) and when you compare the result, you can be sure that analogue tell the true.

[Wuerstchenhund]

What I'm some amount worry is entry level hobbyists who do not know enough and then he can not understand why and what this digital scope show.

I agree, but the way around that is for them to learn and understand their DSO and how it works.

Shortly, for many peoples. Know your equipment, know basic fundamentals. It need learning work but is is only way to get other than just false measurements. With analog scope it is more "safe" and these traps which can drop is less.

Yes, but the proper way for a beginner is to try to understand these limits in the first place and not try to avoid them, especially if EE is supposed to one day become more than an aoocasional hobby.

(about Siglent, yes, in its price class ok for many use and many nice features and building quality very good in its price class and acceptable if do not take price to count...and even protective real glass front of TFT hehe... wait a moment after I get SDG5000 for tests)

As I said in another thread, I really didn't expect much when I ordered my SDS1102CNL scope, but I was really positively surprised (build quality is good, as you say the LCD is protected). My only critics would be the low display resolution (not a real problem, but could be a bit better), the lack of 50 Ohms switchable inputs, and the very simplistic persistance mode (no grading). But again, considering the price, this thing is really good.

And I'm probably well known for not being a great fan of Chinese scopes or entry level scopes in general 

[Wuerstchenhund]

I'am not an expert (I understand only about audio D/A converter that is different).

But for my opion the REAL limit of these digital scope is resolution (8 bit 256 point are not enough).

When I see a sine signal on the analog like 2445 I see a VERY perfections , no any defects about the scope, only the defect of the signal (if there are).

When I see on digital scope (expecially on cheap scope, but not only) I see only some points and the result is not accurate.

Be careful, this is not the same as listening to audio! And yes, for scopes 8bit is generally more than enough even for very high frequency signals (and for the few cases it isn't there are 12/14bit scopes available as well). And while you may think that the signal you see on an analog scope is free from influence, that is not true as even analog scopes suffer from imperfections like frequency-dependent distortions and non-linearities.

Ex: on a screen of 800x600 (256 points are not suffcient to fill 600 points and interpolations or other is a compromise). And apart this, 1 G sample is another compromise that cause inperefect result.

You ignore that not all of the 800x600 screen is used for displaying data points, it also contains the scale and other data like the settings or measurements.

And 1GSa/s is plenty of data for signals say up to 100MHz.

In short if you want Quality and accurate result (>10 Hz, periodic signal) I think no way better then analogue you can find.

I'm sorry but I'm not sure you really know what you're talking about. Please define what you mean by "quality", as again, this is not the same as listening to music.

when I see  a periodic signal (>10 Hz and < 50 Mhz) the result of a analogue 2445 is a REAL result, but with a digital scope < 700 Euro the result can be false and in all case is a compromise (some points no perfect reconstructions like analogue) and when you compare the result, you can be sure that analogue tell the true.

I get the impression you don't fully understand how a scope is used, and you bang on points that are generally of little relevance in most applications. It doesn't matter much that a DSO builds up the waveform from little points while the analog scope 'plots' the signal as it is. A scope is all about displaying information. However, the additional 'fidelity' on an analog scope does not necessarily give you additional relevant information. But with most analog scopes the waveform you see is all you get. On a DSO, the waveform display is just a small part of the information you get, aside from a bunch of additional parameters that would take quite a lot of effort or are simply impossible to get from an analog scope.

I think the term 'oscilloscope' for a DSO is a bit misleading, as it's much more than that. A DSO is really more of a signal analyzer than a traditional scope, albeit it can also be used in this function.

[PA4TIM]

Just make it clear, I'm not against DSOs. I'm agains cheap DSOs operated by people who do not know the limitations. Like I'm against cheap tools in general. Mechanicl snd electrical. If I buy something I wait until I can buy a good tool ( or camara, TV, ect) and I kep using them very long. If they brek I first repir them and exchange them only if they become to old to function. In the long run this is the cheapest way. ( at least for me the last 30 years)
But I become a bit recalcitrant if people talk bad about my precious babys. Analog scopes are history, that is sure.

Not all DSOs are alike. The very high end scopes are in a way more related to analog scopes as to cheap DSOs. And the problem with the hybrids was they were so good you indeed almost never needed the ( whole) analog part. Most times the analog amplified signals were send to the CRT direct or to the ADC nd then to the CRT so you ould add nice functions. i have a hybrid Tek SA who does this.

The difference between high end and cheap scopes is the way they sample. If I would use the output of an anlog sample plugin and send the output of that to an ADC/ uP and LCD display you get the idea. ( btw, using a 132 and 1S1 makes that possible, something like this and will be for me a future project) Much higher resolution and less dead time. The ADC only needs to deal with rather low frequency signals. But in modern high end ( many GHz) sample scopes the sawtooth, stepper ect is made digital intstead of analog. And that is not how a siglent, Owon, Rigol, Agilent 3000 ect work.
( in a very raw nutshell)

I'm a scope collector too so I love to restore and play with analoge scopes.

I know the limitations of both DSO and analog scopes. And like I said in an other topic. If I had to keep 1 scope it would probably be the Hameg DSO ( but I hope I never have to choose, because I'm in love with my 547) if I had to choose between the DS1102E it would be an analog scope for sure, would not have to think more as a second)

This 547 ( and even nicer but I do not have one, the 556) scope including my plugins can do things most DSOs can not even dream of.
- most sharp trace I've ever seen. ( btw the 24XX have , for an analog scope has rather fluffy traces)
- i can measure up to 5 GHz
- measure things with 10 uV/div resolution
- measure very high voltages
- it has several differential plugins, for AC, DC, high voltage, low voltage ect
- high DC offset measurements, the Z plugin can do upto 2000 divisions offset ( max 200V) , no DSO can do this)
- measure transistor timing ( R plugin) ( ok, not very usefull today, but it can do it)
- with the Opamp plugin you can do the wildest things like integration, preamplifiction, measure capacitance ( managed to come down to 1 pF/div), meaure BH curves ect. Just two very good tube opamps in one unit with a buch of in and outputs. Real cool, a build in breadboard in your scope.
- it has a very good delay option and two timebases. Excellent calibrator, 1 mV to 200V
- upto 4 channels, very much trigger options and very good triggering ( you can show two traces and each adjust their own trigger. This I find the biggest downside of a DSO ( but maybe in the high end they have  dual timebase and dual trigger)
- whole lot of input and output connectors
- It does TDR with high resolution using the 1S2
- it can be used as a SA and the 556 can do time domain and frequency domain at the same time ( So a realtime SA and realtime normal trace at the same time, upto 8 traces, Williams used that in appnotes)

The 7000 4 slot can do even more because you can use vertical and horizontal plugins in all slots, so make things like raster displays.

( downside, the 547 works very good as a heater and it gives a new definition to large, including the scopemobile and no cursors, readout ect and that for sure is the best thing of DSOs)
If you do, like most, do only digital then a DSO is first choise. But I'm analog.