Products > Test Equipment

Best Brand Name for an Oscilloscope?

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MrAl:

--- Quote from: rsjsouza on November 30, 2022, 07:17:32 pm ---I would only put Owon's VDS1022/VDS1022I on the category of good price/performance ratio. Others reported several issues with their offers, including some videos from Dave himself.

--- End quote ---

Hi,

Would you happen to have a link to one of Dave's reviews?
I searched but didnt find one yet, except with other members reviews.

nctnico:

--- Quote from: MrAl on December 01, 2022, 12:56:05 pm ---
--- Quote from: nctnico on November 30, 2022, 10:56:43 pm ---
--- Quote from: BillyO on November 30, 2022, 09:05:07 pm ---
--- Quote from: tautech on November 30, 2022, 08:25:25 pm ---Are you making these Billy ?

--- End quote ---
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.

--- End quote ---
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.

--- End quote ---

There is a way to compensate for the rise time of the input wave if that is what you are talking about.
Also, when they quote the 0.35 constant what levels are they touting the rise time is measured at? 
Is it the 10 percent to 90 percent thresholds, or something else?

--- End quote ---
No, this is not the threshold but it is a factor that says how steep the signal amplitude drops with increasing frequency. The number 0.35 only applies when an oscilloscope has a 1st order (RC) roll-off. However, in order to maximise bandwidth and minimise aliasing, a lot of DSOs have much steeper (higher order) filters for which the number 0.35 no longer applies. Since this number is typically not specified (although Keysight does for some of their oscilloscopes IIRC), you can't use a steep edge to determine bandwidth accurately. To make matters worse, the bandwidth can also depend on the V/div setting. For low V/div settings the signal needs to be amplified first instead of attenuated and the amplifier may have a different bandwidth than the attenuator. You see some claiming bandwidths that far exceed what the oscilloscope specifies but it can be completely different at low V/div settings. In the end the manufacturer should specify what the oscilloscope is capable off at all V/div settings. Again, testing with a function / frequency generator at various levels gives you a far more detailed picture of what is going on.

This is what I measured on my GW Instek GDS-2204E:



--- Quote ---There is also the settling time which is rarely mentioned, which i see affects some digital scopes.

--- End quote ---
You mean overload recovery time?

rsjsouza:

--- Quote from: MrAl on December 01, 2022, 12:57:37 pm ---
--- Quote from: rsjsouza on November 30, 2022, 07:17:32 pm ---I would only put Owon's VDS1022/VDS1022I on the category of good price/performance ratio. Others reported several issues with their offers, including some videos from Dave himself.

--- End quote ---

Hi,

Would you happen to have a link to one of Dave's reviews?
I searched but didnt find one yet, except with other members reviews.

--- End quote ---

Duckduckgo'ing for "eevblog owon oscilloscope" yields:
https://www.eevblog.com/forum/testgear/are-owon-oscilloscopes-worth-it/



And the Owon VDS1022/VDS1022I megathread, including even a much improved version of the software modified by the community:
https://www.eevblog.com/forum/testgear/owon-vds1022i-quick-teardown-(versus-the-hantek-6022be)/

BillyO:

--- Quote from: MrAl on December 01, 2022, 12:50:51 pm ---Oh ok that sounds good, but i wonder if that 18 inches of coax is affecting the readings.  As long as it is good coax i guess you're ok there.
--- End quote ---
  Properly terminated coax is a much better bet than any passive probe.  That 18" bit of coax will out perform my 500MHz Tek 6139 probes.



--- Quote from: MrAl on December 01, 2022, 12:50:51 pm ---Interesting little gadget though.  What main chip is that based on?  That really tells all.

--- End quote ---
It's a 74AC14.  It should be able to get sub 2ns Tr, but just.  Maybe 1.7ns.   That's what I'm after.

BillyO:

--- Quote from: mwb1100 on November 30, 2022, 10:06:11 pm ---The bigger problem with Leo Bodnar's (at least the one fitted with the BNC) is that it's out of stock.  I don't know how often he does a build run, but I speculate that pandemic shortages have had an effect and that when he does get stock it goes pretty fast?

--- End quote ---

It looks like they are in stock today.  My order is in..

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