Products > Test Equipment
Recommendation on selecting a used oscilloscope?
BirdManPhil:
I just bought a sds804x this morning after a long hard look at available scopes under $1000 and I can't wait for it to arrive
TomKatt:
--- Quote from: David Hess on June 18, 2024, 07:29:25 pm ---They are an order of magnitude more convenient, but I am not sure about having an order of magnitude greater feature set. They have all kinds of automated measurements, which save time, but it is an oscilloscope, so I am more interested in what the shape of the wave is.
They are more reliable only because they are new and old oscilloscopes are old, but I doubt current DSOs will operate for as long. How many modern DSOs have failed because of failed storage or loss of calibration data? If something breaks, throw it away, and buy a new one.
--- End quote ---
My HP 180A is evidence that 'good' vintage gear was designed to last longer than equipment built today... I can't recall the exact year mine was built but I believe it heralds from 1968 or '69. The only service I've done was to replace the power supply filter caps, which ended up testing fine - I don't think they even needed to be replaced. I highly doubt any modern equipment will have a service life approaching that - in addition to build quality, their relative simplicity also helps their reliability. And if it does ever require service, it's often much easier to repair (provided parts are available). But the problem is that this gear continues to age, so all things being equal they may now have roughly equal service life remaining.
And though many people including myself 'look' at waveforms displayed on a CRO, you are often also doing some rough measuring on the graticule - whether that's amplitude or frequency... Though you may not need the precision offered by modern scope automated measurements, they often are quicker and more accurate than measurements done by eye.
2N3055:
--- Quote from: David Hess on June 18, 2024, 07:29:25 pm ---
--- Quote from: TomKatt on June 18, 2024, 04:15:27 pm ---For everyday use, modern gear is more reliable and provides a magnitude greater feature set.
--- End quote ---
They are an order of magnitude more convenient, but I am not sure about having an order of magnitude greater feature set. They have all kinds of automated measurements, which save time, but it is an oscilloscope, so I am more interested in what the shape of the wave is.
They are more reliable only because they are new and old oscilloscopes are old, but I doubt current DSOs will operate for as long. How many modern DSOs have failed because of failed storage or loss of calibration data? If something breaks, throw it away, and buy a new one.
Things which I would love to do with a DSO which would convince me to buy a new one:
1. Gated RMS noise measurements. My old Tektronix 2440 DSO does this perfectly. My analog oscilloscopes also do it perfectly, albeit not as easily. Some modern DSOs that I have tested simply return the wrong results, maybe from making the RMS measurement on the processed display record?
2. FFT noise density measurements - some very high end DSOs can do this, and as pointed out to me, many R&S models, although I am not clear how far this extends into their lower end models. I need to do a survey.
3. Frequency and phase response measurements - sorry, the current Bode plot thing is a joke, and not even a good implementation of a swept measurement. I want the superior FFT version which operates in real time. Some old DSOs support this, but I will probably have to give up and buy a dedicated low frequency network analyzer for this, which is a shame because it should be so easy on a DSO. Again some R&S models might support this, and LeCroy high end models.
--- End quote ---
First, they don't have to operate that long. New 12 bit 400USD scopes are running circles around many scopes that cost 3000-4000 USD until few years ago. Nobody (except hobby users) wants that old stuff anymore. I would replace it for better, larger screens and much smaller space used on desk alone.
And that old, long running equipment, when was new had comparative cost so high that you could easily buy 20-30 new SDS800XHD for equivalent money today.
It is same as someone told me: That Brymen BM869S looks very good and is much more capable meter than Fluke 87V. But does it have lifetime warranty? My response: "I can buy 3 BM869 for the price of one F87V.. There is your lifetime warranty...."
DimitriP:
With all the features and capabilities, a 747's cockpit worth of instrumentation on one screen.....and for some reason no Timebase Ref input !!!!
2N3055:
--- Quote from: DimitriP on June 18, 2024, 08:39:36 pm ---With all the features and capabilities, a 747's cockpit worth of instrumentation on one screen.....and for some reason no Timebase Ref input !!!!
--- End quote ---
Are you talking about Keysight 20000 USD MSOX3104T scope?
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