Down and dirty beginners oscilloscope?

[tautech]

For some more comparison here are.......
Also I caught one of Dave's GW-Instek reviews, and in their documentation it states when you're set on 1mv/Div they do limit the bandwidth to 20Mhz, so my guess is Sigilent does something similar.

Which Siglent?
If you are thinking SDS1000X series then you are very wrong as they are full BW (not limited) right down to the 500uV range.
https://www.eevblog.com/forum/testgear/siglent-sds1000x-series-oscilloscopes/msg825532/#msg825532

[Muxr]

SDS1072CNL one in this thread.

[tautech]

SDS1072CNL one in this thread.

Yes, at 2mV/div they too are auto 20 MHz BW limited as signified by the highlighted B.

[rf-loop]

For some more comparison here are some examples from the RTM 1054; Full Bandwidth (the trigger is really struggling with all the noise), 20Mhz Bw limit and Averaging:





Also I caught one of Dave's GW-Instek reviews, and in their documentation it states when you're set on 1mv/Div they do limit the bandwidth to 20Mhz, so my guess is Sigilent does something similar.

You tell 1st image have full BW. Why CH4 indicator show "BW"?
AFAIK if there is not any BW limit then there is not BW indicator.

[cdev]

I got a 1980s Tek 2211 on ebay that has a 500 uv/division vertical sensitivity (in the x10 mode) for $75.

And although it is old, its clean and in good shape and appears as far as I can tell to still be within factory specs. With shipping it was a little under $100 I think. It also has some digital features although its quite underpowered by today's standards. But for the money its been well worth it.

Obviously you take a risk with older equipment. I don't think its wise to spend more than a fraction of what you would pay for a new one with similar bandwidth - including shipping, on that vintage/level of used scope - (they may not last very long, because of their age, and that is unpredictable) without considering a newer one as probably a better choice...

But.. all that said, I like it a lot. Its great having access to one.  You can learn a lot more by seeing a waveform than you can from people describing them.

If you paid for a working scope and you received a broken one send it back and make sure you do it through ebay - claiming item not as claimed, and not through email elsewhere, then they have to pay for the shipping.

[Muxr]

For some more comparison here are some examples from the RTM 1054; Full Bandwidth (the trigger is really struggling with all the noise), 20Mhz Bw limit and Averaging:





Also I caught one of Dave's GW-Instek reviews, and in their documentation it states when you're set on 1mv/Div they do limit the bandwidth to 20Mhz, so my guess is Sigilent does something similar.

You tell 1st image have full BW. Why CH4 indicator show "BW"?
AFAIK if there is not any BW limit then there is not BW indicator.

Thanks for noticing that, I took a 400Mhz bandwidth limit one as well and decided not to upload it, looks similar to unlimited, I guess I uploaded it by accident, here is the original unlimited.

[Wuerstchenhund]

Thanks for noticing that, I took a 400Mhz bandwidth limit one as well and decided not to upload it, looks similar to unlimited, I guess I uploaded it by accident, here is the original unlimited.

Wow, that's a lot of noise there. What was your setup (source, cable)?

Just out of curiosity I did a quick check on my RTM1054:




The signal is a 5mVpp 10MHz sine from a Keysight 33522B, going over a H&S RG-58C/U cable with BNC connectors. Source and sink were internally 50ohms terminated.

Trigger was absolutely stable.

[Muxr]

Wow that looks pretty clean, my source is SDG1025, 4mVpp the lowest it will go, 10Mhz, I am actually 1M terminated, 50ohm was worse. I think it's my cable honestly, it's some no name piece of crap. But I did all the other tests with it so I figure I stay consistent.

edit: I ordered some new coax cables, I will do a little comparison once they get here.

[Wuerstchenhund]

Wow that looks pretty clean, my source is SDG1025, 4mVpp the lowest it will go, 10Mhz, I am actually 1M terminated, 50ohm was worse. I think it's my cable honestly, it's some no name piece of crap. But I did all the other tests with it so I figure I stay consistent.

You could test without the generator (but terminate the cable) and see if the noise is still there. If not then it might be that the noise is coming from your Siglent generator.

[rf-loop]

Wow that looks pretty clean, my source is SDG1025, 4mVpp the lowest it will go, 10Mhz, I am actually 1M terminated, 50ohm was worse. I think it's my cable honestly, it's some no name piece of crap. But I did all the other tests with it so I figure I stay consistent.

edit: I ordered some new coax cables, I will do a little comparison once they get here.

Perhaps there is now external noise.  (garbage in = garbage out)

I thing  R&S can not be so noisy what is in image, even with 500MHz BW.  (naturally it can be 7dB over 100MHz scope noise or 4dB over 200MHz scope noise level but it looks now much more. If I compare ecample to 100MHz or 200MHz SDS1000X. This leads to suspect that all this noise is not coming from R&S front end itself.)

If you have attenuators it is better run SDG1000 series generator much higher level and drop level to oscilloscope using attenuator between gen and scope. Example 40dB attenuator.

In my tests there is mostly used something like Agilent 8644B or  old HP8642B  or something like these. These are enough clean least for this kind of oscilloscopes. SDG1025 is not good enough for this purpose directly if we are using its nearly bottom levels.

Of course can use also empty inputs with just 50ohm terminator (if scope itself do not have 50ohm inputs) 
1Mohm it can test example if use 50ohm terminator but inserted only half way so that center pin do not connect or just use metal BNC cap so that external EMI can not pollute input.  But with real signal we get more nice "reality" to peoples who do not have so much experience but also, it may show something about trigger system, "kill two birds with one stone".

[rf-loop]

Thanks for noticing that, I took a 400Mhz bandwidth limit one as well and decided not to upload it, looks similar to unlimited, I guess I uploaded it by accident, here is the original unlimited.

Wow, that's a lot of noise there. What was your setup (source, cable)?

Just out of curiosity I did a quick check on my RTM1054:




The signal is a 5mVpp 10MHz sine from a Keysight 33522B, going over a H&S RG-58C/U cable with BNC connectors. Source and sink were internally 50ohms terminated.

Trigger was absolutely stable.

Here is same with Siglent SDS2k 300MHz inserted to R&S RTM1054 image just for compare.
In this case signal from HP E4421B to blue channel and Siglent SDG5082 to red channel directly and of course both channels 50ohm and M17/84 coaxial cables.
SDS2k  frequency BW is 300MHz and RTM BW is 500MHz what also mean bit over 2dB difference in natural noise level. (more BW more noise)
 Of course this is not good compare because also amount of data is different due ti higher samplerate and different wfm/s speed and also possible some differenvcies in image handling. And then, SDG2k do not have real 1mV/div. It is digitally derived from 2mV/div what is highest true analog front end sensitivity. (More new SDS1kX is very different, it have true 500uV/div full BW sensitivity)

Of course also in this noise question R&S RTM is very good also if we look other higher end professional class equipments.  Siglent is in very different class overall. But if look noise and Siglent here,  it is not bad and and trigger is rock solid.