Flash - NEWS Update on Owon HDS2102 Oscilloscope
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- Опубліковано 5 жов 2024
- Hey y'all!
Quick-ish update video on bandwidth testing and cable tests with the new Owon SDS scope. I'm thinking this is a decent value!
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Yes, cables matter, especially if one is somewhat cluelessness regarding the effects of pushing RF frequencies through improperly terminated 50 ohm coax into a 1 Meg plus 10pF-20pF scope input.
It's NOT "attenuation in the cable" it's the fact that unterminated coax becomes a tuned circuit, and then the coupling becomes a complex function of the impedance and length of the cable and the resulting complex impedance and VSWR. That's why they give you a 10:1 probe with a high frequency compensation adjustment to match it to the scopes 1 Meg plus a few pF input.
I am astonished that you could be knowledgeable enough to understand advanced concepts like that 20 Log E1/E2 formula for decibel calculations, and yet not have ever stumbled across what is by comparison EE 101 stuff like how coax cables need to be properly terminated for precision measurements.
For an accurate high impedance measurement at high frequencies, you need to use the 10:1 probe (after properly adjusting the probes compensation), or as an alternative dodge the high impedance miss-termination issue by forcing the scopes input impedance to 50 ohms with an T terminator at the scope end of the cable. Also, take into account that anytime your signal generator and meter or scope disagree you have to ask yourself which one is in error? Many consumer grade AWGs and DDS based signal generators suffer from uncorrected (or poorly corrected) SinX/X frequency falloff at higher frequencies near the upper end of their range. This is especially true when they are not properly terminated, because the reflected standing waves on the coax play havoc with the signal generators output leveling circuits.
Thanks for watching.
I just got around to trying out the cheap spaghetti thin BNC-BNC cable that came as part of the "bonus" accessories with my HDS2102, and even WITH a proper 50 ohm termination the levels are all over the place and would only stabilize when some side pressure was put on the cable. So turns out that you were right in this case THE CABLE DID MATTER. The scope uses those damn "safety" plastic plated connectors, which make connecting BNC cables a pain anyway, and that and a really crappy improperly crimped cheapy cable they supplied made the cable start to screw up literally the second time it was connected. I chucked it and replaced it with a nice flexible 3 foot RG8 Mini Foam dielectric BNC cable that I soldered and crimped myself about 30 years ago - terminated with a Tektronix in-line 50 ohm terminator at the scope input that's even older than that - and now the levels are rock solid to 1/100 of a volt.
Can you repeat the test with the cable properly terminated in 50 ohms. It is unfair to be "blaming" cables and bandwidth when they are not being used properly.
Thanks I'm loving this scope.
thanks any updates are appreciated
I think it's a decent scope for the price. I will say, it's right on the edge of being priced almost as much as a budget bench scope...but the size of this thing is great to keep at your desk, or in a go bag situation.
This was a great explanation .
👍 It answered a few questions I had.
Thank you
You are welcome!
Try to plug directly these two with BNC adapters and ithout any cable... OUT from signal generator to IN on scope and see results.
very nice overwiew
My wife thinks I'm smart. Then I watch you guys...
Ahhh, Larry - I just google real well! My wife still believes.... Thanks for watching!
Imagine how much difference it would make on long cable lengths. I don't really need one of those but my brain says buy it. Lol. You learned me, is that how they say that down south? Lol
You got some learnin', or you got learnt! (Not really, but hey, let's roll with the metaphor)
😂
@@FEPLabsRadio 😄👌👍
@@FEPLabsRadio Hi, I have the HDS242s works very well, trigger options are not the best.
Do you know if this model have some trigger improvement?
Cursos or something better?
Thanks in Advance
Nice job with the video! #CablesMatter
Hello, can you use the multimeter leads to input and see the sinewave from an electrical socket? I've been searching everywhere for this answer as i'm new to oscilloscopes.
Zack - you need to be SUPER careful hooking this to mains power. Yes, you can do it. BUT, you need to make sure you understand the max voltage input on the scope, you need to understand what ground reference you're using. As this is battery powered, you have a floating ground. Just make sure you're careful about not crossing your leads up, or touching the bare ground lead clip. I'd recommend you study some youtubes and user manuals. It is entirely able to do what you're asking, but you're playing with mains level voltage.
get a bnc to scope probe connector, testec probes come with those
I just got this scope as well. A sweet little portable scope for the money IMHO.
Question that I have... I know you can enable measurement displays along the bottom, but why does the scope always display the frequency at the top right corner no matter what you enable/disable along the bottom. Is this just a redundant display of measured frequency? If so, just wondering why they would choose to do so (making it available as a display at the bottom).
I believe so, I could never get it to go away either
@@FEPLabsRadio Hardware frequency, can switch
[HOR]-->[Counter OFF]
OWON HDS2102S vs Tektronix THS720A
Which of these two devices would make sense to buy?
It depends on your budget. Tektronix makes OUTSTANDING products, truly quality top-of-the-line. However, 800$ vs $200. It comes down to budget, and what your actual needs are. The Owon is not in the same league as that Tek scope, and the price shows that.
Transmission line should be properly terminated. Otherwise standing waves rouin measurements.
Can I check the oscillation frequency and waveforms of switch mode power supplies with this scope?
As long as those frequencies are within the bandwidth capability of the scope, which for this model, they would be.
@@FEPLabsRadio thank you so much for the reply. I have ordered the model that comes with the waveform generator. I already have a great success rate at fixing SMPSs by using a decent multimeter and a few tricks I learnt from youtube that allows to know whether oscillations exist or not. But this equipment is gonna quench my long thirst of seeing the thing for real. I'm grateful for such helpful content. Will keep an eye on your channel.
Your scope is 1Mohm and the cable is 50 ohm - you need a coupling
The scope can be 50ohm as well.