2nd, more modern oscilloscope choice, or help in the problem with current one - Page 1
Forum section: electronics / beginners

author: Mateusz
author_rank: Newbie
timestamp: March 06, 2022, 11:13:37 pm
content: Hi there.I am not a frequent visitor on this forum, however i thought it would be nice to ask some of more experienced people around here about the current decision i'm about to make. I am sorry to make a big post with wall of text, but i would like to be comprehensive and communicate the most of what's going on in my head.There is more than a good chance you don't remember me so i will reintroduce myself. Couple months ago i was looking for my very first oscilloscope, and i was making some really wide assumptions on what would i like to buy and such. In short, if you don't want to read entire topic (which is here:https://www.eevblog.com/forum/beginners/the-more-i-read-the-more-clueless-i-am-of-which-scope-to-buy/), I personally settled on buying an older scope, i chose digital HP 54645D, which is mixed domain 200MS/s 100MHz scope, that came with additional FFT/storage module on the back. It is really nice, and belive it or not, I actually got a job as programmer/tester in company that assembles battery packs, and i had the reason to use it while i was working HO (home office). In other words - it first helped me got the job (i used that for hobby projects previously), and then helped me IN the actual job. Thus i think investment paid off.I decided now to invest in some more modern choice. The main reason is to actually have some basic modern functionalities, or more bandwidth to explore more things. Modern in sense - connecting to external PC (LAN/USB? maybe some manufacturer has the application to control the scope remotely?), USB stick to screenshot, I2C/UART/SPI decoding that i could observe to troubleshoot designs automatically (i had to manually observe the waveform on the HP before and look what was not right, decoding the protocol in my head), maybe some better sampling rate, and so on. So here are my choices i currently have:1. I got an offer (I was negotiating the price) for R&S RTC 1002, RTC1K-COM2 version, for about $860 (a little bit less, meanwhile official shops has it listed localy at $1300-$1600? idk). It comes with all the necesairy equipment (logic analyzer probe, unfortunately 8bit (i think), 2 other probes, power cord, and ofc scope). It also comes from the seller that is local so no bulls*** with import taxes, expensive shipment and such. Is this the good price?2. I could try to refuse the offer and try to think about the Siglent SDS2xxxX plus (or something), idk how much would the MSO option cost, since it is now not only the software (which there seems to be hacks for), but also the physical logic probe which is worth about $400 alone on ebay (at least)3. I did see very cheap offer for far higher bandwidth scope, in the same price range, but broken, It is a lecroy 7200 (yeah that's quite some leap and quite some absurd comparison to the previous ones, i know, i still did not give up thinking about high bandwidths yet..., i'm just obsessed with oscilloscopes to this day) on ebay (you will easly find it, a lot of observers currently). Long story short, the seller claims most of the stuff "works properly" (clocking part, PSU, and one more) but the FPGA unit there isn't working.4. Finally - loking more, to find maybe a scope that is the middle-ground (like idk older scope with 500MHz? there is a Tek TDS7xx (i think) that is around at this price point) and don't bother the modern options (like the USB to PC connectivity, or LAN cable)So here are questions:1. Siglent has some astronomical 200M/ch memory depth and "120k wfm/s", meanwhile R&S has like, 2M memory/ch and "10k wfm/s". Also Siglent seems to come with the 2M FFT, while R&S has about 128k FFT. Meanwhile R&S comes with the 300MHz BW (and the option for sig i was looking for was 100MHz). What do you think about comparison of these 2? What is the impact of such a big memory/waveforms_update on the capture of the signal, or is this actually "less" but the data can be viewed historically (like many aquisitions, and then historical view)?2. How hard is it to troubleshoot such an FPGA problem? I can provide you the feedback (DM) of what the seller replied to me when i asked about the details of this issue.3. On my recent scope i have about 30 MHz ringing while poking around higher frequency signals (for example 400kHz I2C is good, but when choosing really low time/div of about 5-20ns, on test signal rise there is ringing). What could be possible reason to this problem? I tried poking the 24MHz crystal on my FPGA programmer (i got Maximator FPGA, Intel MAX 10, 8k gates, starter borad to get more familliar with logic gates, crystal is on JTAG programmator board) and it is the same. I use Agilent 150MHz passive probes (i belive it is 10074C or something like that, can't remember from the top of my head). I could use the second scope to possibly probe around and diagnose the problem. Or is this something trivial?4. I come from Poland so the prices that i "tell you about" are show "recalculated to USD" by me and now are changing quickly (4.5PLN to 1USD as of this msg), due to the european situation. Currency value drops heavly and is not stable, which makes purchases from ebay a lot more unsafe.

author: FlexibleMammoth
author_rank: Regular Contributor
timestamp: March 07, 2022, 12:31:08 am
content: Ok so short version because I really need to get some sleep1. I have owned both the R&S HMO1202 full options (look it up, it's identical to the RTC plus additional 50Ohms input) and the Siglent SDS5000X full options. In 2022, the R&S is only nice if you got no bench space. Siglent is better in almost every other way (yes, even the SDS2000X Plus). Touchscreen, screen size, memory, bandwidth. R&S advantages are component tester, nice XY view with X(t) view, pattern generator. You can hack the Siglent, not the R&S. Personal opinion: I almost never need the big memory, but always need the big screen & touch. More wfms means you'll see more glitches. Numbers are marketing that are only reached in special circumstances.2. Not qualified to talk about that. Most likely complicated unless it's a bad solder joint or you have the tools, and a known good donor board/spare part.3.Try shorter lead lengths, there should be a small spring in the probe accessoires that you can attach instead of the long ground lead. Also, fundamental frequency is worthless, but rise time of the signal is important. A very sharp square wave at 1kHz can have components beyond 500MHz, which eventually hit the resonance of your lead inductance & tip capacitance.4. That will probably be the case for the forseeable future.

author: tautech
author_rank: Super Contributor
timestamp: March 08, 2022, 03:37:31 am
content: Quote from: Mateusz on March 06, 2022, 11:13:37 pmCorrection:SDS2000X Plus use two 2GSa/s ADC's each with 200 Mpts memory support which with 4 active channels divide it down to 1 GSa/s and 100 Mpts max/channel.Thread here:https://www.eevblog.com/forum/testgear/siglent-sds2000x-plus-coming/Comparison thread:https://www.eevblog.com/forum/testgear/functional-comparison-of-rs-rtb2000-siglent-sds2000x-and-keysight-dsox1000/

author: Mateusz
author_rank: Newbie
timestamp: March 16, 2022, 10:29:49 pm
content: Quote from: tautech on March 08, 2022, 03:37:31 amThanks for clarifying thatQuote from: FlexibleMammoth on March 07, 2022, 12:31:08 amThanks for answering that, I'll look into this a little bit more.Quote from: FlexibleMammoth on March 07, 2022, 12:31:08 amok so i did tried this but results are even weirder now, i'll make a video post tomorrow so you will see what i have in mind/what i'm looking at. Basically, with NO GROUND CLIP connected (the aligator clip detached + no "ground spring" - what i really have in the 10074C accessories is a plastic shield with metal rigid wire that extends out), i can kind of see the sinusoid from the crystal on one of the 4 legs of the SMD package. When i grab and mount the short ground lead, and connect GND to top of the SMD, waveform becomes a square wave O_o... What is going on? I tried both AC coupling and DC coupling, but at 24MHz i belive, apart from the constant voltage offset, i won't see any meaningful difference.In terms of ringing i wached Alan's (do i remember name right? w2aew yt channel) video about probe compensation but the probe i use is rate to 9-17pF input cap. and the HP54645D has 13 so i guess it is in spec, i noticed i might have some additional interference beacue i keep the scope to many other devices and maybe they interfere? (like for example switching power supplies for some mobile phones that EMI at some freq that causes resonance closely?) Let me know if this could be a potential problem and if i should test this out in some less busy environment.

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: March 17, 2022, 01:16:08 pm
content: Mateusz:I am not an engineer. I dropped out of eng school after two years. Went into something else. I am a Hobbyist.I have had all sorts of analog scopes and decided to get into the 21st century.You mentioned possibly an older "middle ground" scope, so:I purchased an Agilent 54810 500 MHz Scope that had been upgraded to 2 GSa/sec and a solid state drive. Essentially upgrade a 54810 to 54820. Easily done, apparently.The 54815 has four channels vs my two channels, 54820 and 54825 have 2 GSa/Sec.I realize that it does not have any logic capabilities outside of the scope channels.It does have LAN and USB capabilities, connections are on the back, I have never used them.Memory depth is only 32,768 points per channel.I am not impressed with the FFT function. it works but a spectrum analyzer seems to me to be much better.Since you are already using an HP Scope, perhaps it is something worth looking into.Perhaps a stand alone Logic analyzer with one of these scopes would be less expensive and a better, more versatile choice. Maybe less expensive also.I do not have a modern Tek scope, but some people prefer them rather than the HP/Agilent scopes.Anyway, Just an idea......I don't know about the availability of these things in Poland, have not been there in many years.