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Best Brand Name for an Oscilloscope?

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tautech:

--- Quote from: bdunham7 on December 01, 2022, 12:35:37 am ---
--- Quote from: nctnico on November 30, 2022, 10:56:43 pm ---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.

--- End quote ---

"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.

--- End quote ---
See if your calculator tells us which model this is.

BillyO:

--- Quote from: tautech on December 01, 2022, 01:12:36 am ---See if your calculator tells us which model this is.

--- End quote ---
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:

--- Quote from: BillyO on December 01, 2022, 01:24:53 am ---
--- Quote from: tautech on December 01, 2022, 01:12:36 am ---See if your calculator tells us which model this is.

--- End quote ---
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.

--- End quote ---
Just checking someone would ask for that.  >:D
30ps

BillyO:
Then my guess would be an SDS2204XP.

nctnico:

--- Quote from: BillyO on December 01, 2022, 12:58:08 am ---
--- Quote from: nctnico on December 01, 2022, 12:25:42 am ---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.

--- End quote ---

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.

--- End quote ---
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.


--- Quote ---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.

--- End quote ---
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.

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