Best Brand Name for an Oscilloscope?

[nctnico]

Are you making these Billy ?

I may, once I have them where I want them and there is enough demand for them.  Otherwise I can just make the files available.

Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't. The only proper way to measure the bandwidth of an oscilloscope is to sweep the input using a levelled RF generator.

[BillyO]

Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't. The only proper way to measure the bandwidth of an oscilloscope is to sweep the input using a levelled RF generator.

I wouldn't say nothing.  Neither would Tektronix.  Neither would physics.  It's not absolutely accurate, but it will let you find out if your FNIRSI is more like 30MHz than 100MHz or your SDS1104X-E is more like 120MHz than 100MHz.

Of course the proper way is to sweep the frequencies, but not everyone can afford a 500MHz AWG to check out their 200MHz scope.  However, they could probably swing $5 or $10 for a handful of readily available components and a PCB.

A small few of the folks around here ( ) are not fixing heart-lung machines or calibrating self-guided nuclear missiles.  They just want to have a little fun with electronics and their lab kit.  Knowing the BW or their $600 scope to +/- 10% might be enough.

All that said, please rest assured I'll check myself before I wreck myself and not get too wound up.   

[nctnico]

Well, you can buy a simple function generator to check the bandwidth of an oscilloscope. Like one from Uni-t or Feeltech. That is a lot more useful compared to wasting money on a device that just outputs a square wave. And likely the 1kHz calibrator output of the oscilloscope already has steep enough edges.

[bdunham7]

Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't.

"Nothing" is a bit overstated--risetime gets you in the ballpark for bandwidth and whether the factor is 0.35 or 0.45 is a detail.  And I'd say that in a lot of cases, perhaps most, where the factor does significantly diverge from 0.35, the user may actually be more concerned about rise time than actual bandwidth.

[BillyO]

Well, you can buy a simple function generator to check the bandwidth of an oscilloscope. Like one from Uni-t or Feeltech. That is a lot more useful compared to wasting money on a device that just outputs a square wave. And likely the 1kHz calibrator output of the oscilloscope already has steep enough edges.

A cheap 30MHz FG is not going to tell you much about the BW of your 200MHz scope unless it has a rise time of less than 2ns.  They don't.  No probe compensation calibrator I know of does either.

The fact is the transient response of a system is directly related to it's bandwidth and with careful measurements you can get a very close determination of that bandwidth.

Here are some articles on it.  If these don't give you enough information, there dozens.
https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=9817
https://www.signalintegrityjournal.com/blogs/12-fundamentals/post/853-back-to-basics-bandwidth-and-rise-time
https://eng.libretexts.org/Bookshelves/Electrical_Engineering/Electronics/Operational_Amplifiers%3A_Theory_and_Practice_(Roberge)/03%3A_Linear_System_Response/3.05%3A_RELATIONSHIPS_BETWEEN_TRANSIENT_RESPONSE_AND_FREQUENCY_RESPONSE

Besides, a high slew rate pulse generator has many other uses.

[tautech]

Before you get all wound up about risetime, be aware that risetime tells you nothing about the bandwidth on an oscilloscope. When using risetime the assumption is that the 0.35 number is constant for all oscilloscopes. Unfortunately it isn't.

"Nothing" is a bit overstated--risetime gets you in the ballpark for bandwidth and whether the factor is 0.35 or 0.45 is a detail.  And I'd say that in a lot of cases, perhaps most, where the factor does significantly diverge from 0.35, the user may actually be more concerned about rise time than actual bandwidth.

See if your calculator tells us which model this is.

[BillyO]

See if your calculator tells us which model this is.

We don't have enough information.  We would need to know the minimum rise time of the pulse generator.  if it's only capable of 2ns, then this could be any scope with a BW > 200MHz.  If the pulse generator is capable of much faster than 2ns, then this is any model of Siglent that has about a 200MHz actual BW except the 1000 series scopes.

[tautech]

See if your calculator tells us which model this is.

We don't have enough information.  We would need to know the minimum rise time of the pulse generator.  if it's only capable of 2ns, then this could be any scope with a BW > 200MHz.  If the pulse generator is capable of much faster than 2ns, then this is any model of Siglent that has about a 200MHz actual BW except the 1000 series scopes.

Just checking someone would ask for that. 
30ps

[BillyO]

Then my guess would be an SDS2204XP.

[nctnico]

Well, you can buy a simple function generator to check the bandwidth of an oscilloscope. Like one from Uni-t or Feeltech. That is a lot more useful compared to wasting money on a device that just outputs a square wave. And likely the 1kHz calibrator output of the oscilloscope already has steep enough edges.

A cheap 30MHz FG is not going to tell you much about the BW of your 200MHz scope unless it has a rise time of less than 2ns.  They don't.  No probe compensation calibrator I know of does either.

I own and have owned several oscilloscopes that have calibrator outputs with very steep edges. And ofcourse a cheap generator isn't going to cut it but then again a 200MHz bandwidth oscilloscope isn't in the budget class either and doesn't need checking of the bandwidth; it will work. It is the bottom of the barrel, sub US $100 scopes that require some testing to determine actual bandwidth and a cheap 60MHz function generator (even those go way beyond 30MHz) is good enough to do that. And it is useful as a general tool. And then again, Aliexpress and Ebay are full of low cost HF generator boards that are suitable up to hundreds of MHz with a reasonably constant amplitude.

The fact is the transient response of a system is directly related to it's bandwidth and with careful measurements you can get a very close determination of that bandwidth.

Again, the number 0.35 doesn't apply to digital osciloscopes in general because the first order roll-off isn't a given. You may be off by +/-25% if you use the risetime.

[tautech]

Then my guess would be an SDS2204XP.

Based on what calculated BW ?

[BillyO]

Based on what calculated BW ?

Yes, and my limited exposure to other 2000 and higher Siglent scopes.  It might also be a 2000HD model, but the base 5000 and 6000 both are much higher BW than 200MHz so should show quite a bit less than 2ns.

[BillyO]

I could also add that it being 3pm in NZ you are likely still at work so this would probably not be an "improved" scope.

But, as I said, I'm just guessing.

[tautech]

Then my guess would be an SDS2204XP.

Based on what calculated BW ?

Yes, and my limited exposure to other 2000 and higher Siglent scopes.  It might also be a 2000HD model, but the base 5000 and 6000 both are much higher BW than 200MHz so should show quite a bit less than 2ns.

Yes but the pic title already tells you the model series is 2kX+ so now where are your calcs ?

TBH your guess of SDS2204X Plus could conceivably be miles out unless you do your homework on the BW of each model in this series.

I could also add that it being 3pm in NZ you are likely still at work so this would probably not be an "improved" scope.

But, as I said, I'm just guessing.

Nope, it's NIB unaltered.

[BillyO]

Again, the number 0.35 doesn't apply to digital osciloscopes in general because the first order roll-off isn't a given. You may be off by +/-25% if you use the risetime.

Tektronix suggest using .45 for most DSOs.  Others suggest .40.  Being the physicist I am, I just wave my hands and use .425.

[BillyO]

Yes but the pic title already tells you the model series is 2kX+ so now where are your calcs ?

TBH your guess of SDS2204X Plus could conceivably be miles out unless you do your homework on the BW of each model in this series.

The BW of the 200 series are 100MHz, 200MHz and 350MHz (and sometimes 500MHz)

So, calcs ..

T_r=~ 0.425/BW

100MHz:  T_r =~ 0.425/100MHz = 4.24ns

200MHz:  T_r =~ 0.425/200MHz = 2.12ns

350MHz:  T_r =~ 0.425/350MHz = 1.21ns

Your screen shot showed 2ns so 200MHz is the closest.

I didn't notice the filename so now I'll say I'm 95% sure it's and SDS2204XP.

[tautech]

Yes but the pic title already tells you the model series is 2kX+ so now where are your calcs ?

TBH your guess of SDS2204X Plus could conceivably be miles out unless you do your homework on the BW of each model in this series.

The BW of the 200 series are 100MHz, 200MHz and 350MHz (and sometimes 500MHz)

So, calcs ..

R_t=~ 0.425/BW

100MHz:  R_t =~ 0.425/100MHz = 4.24ns

200MHz:  R_t =~ 0.425/200MHz = 2.12ns

350MHz:  R_t =~ 0.425/350MHz = 1.21ns

Your screen shot showed 2ns so 200MHz is the closest.

I didn't notice the filename so now I'll say I'm 95% sure it's and SDS2204XP.

It is but......
https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/msg2958288/#msg2958288

SDS2104X Plus has a -3dB BW of ~185 MHz and is the reason it's supplied with 200 MHz rated probes.

Based on that you might trim your calcs to better fit with a 30ps pulser. 

Yeah, I set you up. 

[BillyO]

Well, I didn't know that about the SDS2104XP even though I have one.  Nice scope!

I actually "improved" it within minutes of getting it out of the box so never tested in it's NIB mode.

There is actually a story about my "improvement journey" which I will relate to the forum when I verify some things.  As it is right now I'm seeing about 700MHz BW using a frequency sweep, but this is one of the things I need to verify.  More on all this later in a different thread.

Anyway, our little banter here verified my assertion that a transient response can get us very close.  Can you do a frequency sweep on that scope to see how close we came?  It might even be a tad better than the 185MHz.

[nctnico]

Based on that you might trim your calcs to better fit with a 30ps pulser. 

That is the problem: in the end you can't determine the exact bandwidth using a pulser because you don't know what the roll-off 'factor' of the front end is.

[tautech]

Well, I didn't know that about the SDS2104XP even though I have one.  Nice scope!

I actually "improved" it within minutes of getting it out of the box so never tested in it's NIB mode.

There is actually a story about my "improvement journey" which I will relate to the forum when I verify some things.  As it is right now I'm seeing about 700MHz BW using a frequency sweep, but this is one of the things I need to verify.  More on all this later in a different thread.

Anyway, our little banter here verified my assertion that a transient response can get us very close.  Can you do a frequency sweep on that scope to see how close we came?  It might even be a tad better than the 185MHz.

IIRC SDS2504X Plus BW is nearly 600 MHz and it's reported somewhere in the 2kX Plus thread.

First SDS2104X Plus we got hands on is what I tested and as reported in the link to post above and I flat out didn't believe it was ~185 MHz but tested with 3 yes 3 sinewave sources confirmed it was. 
I'd never seen the likes of rated BW exceeded by 85% in any instrument.

Missing my now sold SSG3021X already. 

[BillyO]

That is the problem: in the end you can't determine the exact bandwidth using a pulser because you don't know what the roll-off 'factor' of the front end is.

No one said exact.  We're not going for exact using this method.  In this little exercise I came up with 200MHz, we don't know the actual, but it is assumed to be 185MHz for now.  That's an error of less than 10%.  If you had a T_r of 2ns doing a transient test you'd be correct in saying "My scope has about a 200MHz bandwidth".  Which is really quite significant if your scope is advertised as a 100MHz scope.  Likewise, if you did the test on your supposed 100MHz scope and got 13ns you'd be safe in saying the rating of the scope is an out and out lie and reality is more like 30MHz.

[BillyO]

Missing my now sold SSG3021X already. 

Now, that would be an awesome SG.  I see them for $3600 CDN for the base model .. more than I can really ever afford after just spending nearly $4500 CDN on two scopes, an AWG, a DMM and a DC load in the last 4 months.  All Siglent.  I'm afraid such a thing is out of my hobby league.

I'll have to continue to live with my ADF4350 ..

[tautech]

Missing my now sold SSG3021X already. 

Now, that would be an awesome SG.  I see them for $3600 CDN for the base model .. more than I can really ever afford after just spending nearly $4500 CDN on two scopes, an AWG, a DMM and a DC load in the last 4 months.  All Siglent.  I'm afraid such a thing is out of my hobby league.

Yeah that's the trouble, they don't get lots of use unless you're right into RF. Even a SDG6052X is not exactly cheap but either of these base models can be improved. 
However even if we were to replace it with the same SSG and again improve it to 3.2 GHz that's not high enuf to test what's coming from Siglent. 
SSG5000X can do it but that's another jump in cost. 

[BillyO]

.. 3.2 GHz that's not high enuf to test what's coming from Siglent. 

Sounds very interesting!  But also sounds like something I'll never own.

When will it be announced?

[tautech]

.. 3.2 GHz that's not high enuf to test what's coming from Siglent. 

Sounds very interesting!  But also sounds like something I'll never own.

When will it be announced?

When we spot it on the HQ website and know it exists for real. Only heard whispers about it thus far.