EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Dunckx on March 10, 2021, 03:08:54 pm
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Hi Folks,
This is my first post so a bit about me...
I've been lurking for a while and doing a lot of learning, both here and via YouTube. Projects currently on the go involve voltage references (I've never had one and it's about time) Conrad's Kelvin-Varley divider and analogue stuff of various kinds. I've been playing with electronics since the mid-60s when - as with so many youngsters - I started building stuff on the kitchen table with Dad's encouragement. I have accumulated an excessively well-stocked junk box over the intervening decades and now I am nearing retirement intend spending the remainder of my days having some fun with it all. Last year I supplemented my handheld Meterman 37XR with a refurbished (read: "Pyrotechnic mains filter replaced") Solartron 7150 plus, the first bench multimeter I've owned and a bargain at just over 100 UK pounds from http://www.surplustest.co.uk/product.php?id=40 (http://www.surplustest.co.uk/product.php?id=40) inclusive of the filter swap. I believe they still have some left, they must be MOD surplus or some such.
I am now looking for a digital scope and have been reading many extensive threads here, and although I have yet to arrive at a decision, reading through the voluminous threads and watching YouTube vids has at least given me the chance to refine my mental picture of what I need this scope to do, and eliminate those things I do not need it to do. There are so many scopes out there with impressive specs that I am finding it very difficult to narrow down the choices and I need your suggestions. I have devised a reasonably specific description of the roles this thing will have to fulfil. It may well be that I can't get all my "must haves" and will have to settle for less. Please take a look at the list below of wants and don't wants, and suggest a shortlist of possible scopes for me to investigate further. After much reading and thinking, the spec is:
* The instrument will be used on analogue signals only. The analysis of digital signals is not required and would never be utilised.
* Low noise floor is a must.
* Two channels is plenty.
* Bandwidth is not an issue. I'm not allergic to it but there's no point in paying extra for it as 90% of signals will be under 10MHz.
* Vertical resolution is good. 8 bits is OK-ish and I'll put up with it if I have to, but more than 8 bits or oversampling is preferred as it will in part be replacing an antique, space-hungry, noisy and very heavy 12-bit system.
* High pixel count screen is preferable.
* Screen capture/file export to USB stick, SD card or similar required. No problems formatting sticks or using sticks formatted on PC. It would be useful if the data were in such a format as would allow easy import into Maple or Mathematica.
* FFT, cursor measurement and mathematical operations, preferably included in the instrument price as opposed to an optional extra.
* External trigger input, and output if possible.
* Component testing/curve tracing would be nice but not essential.
* Network connectivity not required. Maybe useful if present but not worth paying extra for.
* Touch screen not required.
* Signal generator not required.
* Autosensing of x10 probes not required.
* A stand-alone scope, not a PC scope.
* "Intuitive" interface, by which I mean the most-used resize and scroll and maths functions should not be buried at the bottom of a menu stack, and individual controls for each vertical channel would be good. Twiddling knobs is more attractive and, dare I say it, more gratifying (pfnarr pfnarr, yuk yuk.)
* Solid ergonomics, no cheap, wobbly encoders or sloppy switches. Detents are good.
* Unfortunate limitation - it must be available from within the UK so if possible please name a supplier. ("Brexit, to the last I grapple with thee; from hell’s heart I stab at thee; for hate’s sake I spit my last breath at thee..." >:D)
For the last 35 years I have been used to a CROtech 20MHz dual channel CRT scope with 2mV/div max sensitivity which I got from one of the four Henry's Radio shops down Edgware Road in London, if anyone remembers them, and I am keeping this old solid state soldier for work on valve HT circuitry. Besides which, a real oscilloscope always contains a fundamental subatomic particle accelerator and lots of volts, Igor :) The reasons for buying digital are:
* Waveform storage/logging and post analysis, either on the scope or on a PC.
* FFT, onscreen measurement with cursors and math/dsp functionality. I'm hoping to replace/retire a Data Precision aka Analogic 6100 dinosaur, which has a plug-in covering up to 100kHz at 12 bit and don't really want to lose out on more resolution than I have to.
* Lighter weight (I now have a pacemaker and have been told not to lift heavy objects) and smaller.
* This will be my last scope purchase and must see me off the planet.
I have a budget of 1500 UK pounds and if I can do it for half that, so much the better. However, the upper "limit" is elastic if it really has to be. But I'll need some strong persuasion.
What say you?
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If a PC scope is out of the question then the R&S RTB2004 would be a reasonable fit. Mostly for having 10bit resolution. Lecroy's HDO series (12 bit) could also be an option but might need stretching the budged further even when bought used.
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You don't say what signals you will be measuring (audio, rf, mechatronics...)
Low noise implies low bandwidth.
Make sure you understand the consequences of the number of bits and FFTs.
For £1500 there should be many options, particularly if you are prepared to buy secondhand or at auction.
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The 2ch SDS2102X Plus is an excellent fit for the OP's requirements.
Btw, welcome aboard.
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You don't want PC scope, but Picoscope 4000 series would be superb spec wise: advanced arbitrary math, high performance FFT.
Model 4444 is 14bit/20 MHz deep memory scope with true differential inputs, SFDR > 70 dB.
Model 4262 is 16bit/5Mhz scope with
Harmonic distortion –95 dB typical @ 10 kHz, –1 dBfs input
SFDR 96 dB typical @ 10 kHz, –1 dBfs input
Noise 8.5 µV RMS (on most sensitive range)
It also has DC-20KHz AWG signal generator capable of low distortion sinewaves..
So really shame you don't want PC based scope. It would enable you to measure many things no standalone scope would, and it is also less than 900 GBP.
If I were you, I would take one of these and, as you intended, keep the CRT scope for other stuff..
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If you need more than 8 bits then the Rhode and Schwartz RTB2002 or Siglent SDS2102X Plus are good choices (both have 2 channels)
If 8 bits are OK and you can live with the smaller screen then a Siglent SDS1104X-U will probably be good enough (at a third of the price of the other two). It has a 128k point FFT.
Siglent is available in the UK: siglent.co.uk
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Thank you so much for coming back so quickly, I really appreciate your advice. I will be looking at RTB2002/4 and Siglent SDS2102 Plus.
@2N3055, I know of the Pico scopes, they've been around a fair while now and they do have a good reputation, but I forgot to say in my OP that the main reason I'm not going for a PC scope is simply because I have no laptop and there's no PC in my "den". I have nothing against them per se and I should have made that clear. My omission!
Again, thank you all for your time and words of wisdom.
I have just had a very brief look at the RTB...is there a good reason not to consider the much cheaper RTC1002?
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Well, I've just answered my own query regarding the RTC. I hadn't realised from the pictures that its screen is significantly smaller than the RTB2002. I did wonder if the oversampling feature to boost resolution to 16 bit would compensate and save some cash, but whilst I still have more reading and viewing to do, I think it's going to be the RTB2002 for me. I decided not to go for the Siglent because of the (to me) bizarre "history" feature which Dave talked about in EEVblog 1312. That would irritate me no end.
Thanks again one and all for your most helpful input.
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Have RTC1002 and RTB2004 on the bench, will give back RTC1002, the touch is definitely a huge plus on the RTB. Much faster operation when setting up Busses and entering numbers.
But the con is the size. The RTC has a very nice compact size. smaller than 1054Z.