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MSO5000 Bode Plot Capability: Is it Good Enough? [Many tips about a 1st scope]
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jasonRF:

--- Quote from: balnazzar on October 09, 2022, 05:42:49 pm ---
--- Quote from: jasonRF on October 09, 2022, 02:40:23 pm ---
But any 5000-series pico has 8 independent ADCs (I think that's why they can get to 16 bit resolution.. By stacking ADCs..)

Dave did a teardown of a 5000B scope a bunch of years ago (I think it was a 5443B), so I know that it has a single ADC chip that draws something like 1/2 Watt.  It is a very specialized chip, and they basically designed their scopes around it.  I suspect they use that same chip in the current 5000D series, unless it is obsolete.     

Regarding FRA4Picoscope, it works fine with my 2204a, the cheapest Picoscope in the current lineup.  For years that was my only scope and I used that app many times.  There are examples from at least two different 2000-series (including my 2204a) in the thread
https://www.eevblog.com/forum/testgear/picoscope-2000/

jason

--- End quote ---

Thanks for the information!

I was making reference to this forum post: https://www.picotech.com/support/topic14311.html
Particularly, the third post from above. Says that the 2204A has something that hinders the FRA app. Maybe it was solved in the successive software releases?

About the 5000 series, they advertise them as having eight (!) ADCs. Maybe it's just for the lastest 5000 series models?

One question about that little 10 MHz scope. How often did you hit the bandwidth limit in your work? For example, you were able to accurately observe transients up to which frequency?

Thanks!

--- End quote ---
That post about lack of support for the 2204a is from 2014.  There have been many improvements to FRA4Picoscope since then!

Regarding bandwidth, my particular unit has a -3dB bandwidth around 25 MHz give-or-take.  It also falls off relatively slowly, depending on which vertical scale setting you are in.  If I forget to use a decoupling cap on an op amp and it is oscillating at 20 MHz it is no problem to see it.   Likewise, when I have built discrete audio amplifiers that had transient induced instabilities (eg “fuzz” showing up after the falling edge during square-wave testing).   Bumping up the compensation capacitor to the next one in my drawer made the fuzz go away.  But if I had an emitter-follower with a parasitic oscillation at 150 MHz I would be blind to it.   Not that I think I have run into that, but increased bandwidth was the primary reason why I upgraded this year.   My review in the thread I linked has more info on my thoughts about the 2204a. 

Jason
balnazzar:

--- Quote from: jasonRF on October 09, 2022, 06:33:31 pm --- My review in the thread I linked has more info on my thoughts about the 2204a. 

Jason

--- End quote ---

Reading right now, thanks! :)
balnazzar:
Just as reference for people who comes reading this thread, here is an RLC circuit captured with the AD2, while the AWG makes a sweep 50-20K, with the FFT below. How cute :)

https://youtu.be/DvlKVv5lGa0

I still have to figure out why the non-peak frequencies do exhibit that pulsation.. It's interesting.. 
nctnico:

--- Quote from: jasonRF on October 09, 2022, 12:39:45 am ---
--- Quote from: balnazzar on October 08, 2022, 06:21:55 pm ---
Bottom line: chinese scopes tend to be noisy (and in the case of the MSO5K, not only acoustically...). That's what I don't like about chinese products in general. They tend to deliver stuff that works, but they are always kind of half-finished. How much more would cost to be a bit more attentive to the acoustical noise? Almost nothing. A better fan, PWM control, maybe make the scope 1 cm thicker and put a 120mm fan on the back, exhausting from the side vents..

--- End quote ---
At work my office door opens into an electronics lab packed with high-end gear made by non-Chinese companies (Tek, Agilent, R&S, Anritsu, Keysight, etc.) and it is loud enough that I need to keep my door shut in order to hear myself think.  While I know I am extra sensitive to the noise, it leads me to suspect that the nationality of the company may not have a lot to do with this.

--- End quote ---
From what I have seen over the years is that older equipment tends not to be designed with acoustic comfort in mind. In some cases the amount of airflow is overkill for normal, room temperature operating conditions. I have a couple of HP6012A (1kW lab supplies) and I have modified these with thermal controlled fans (at low RPM by default). Even under high load, the fans don't spin any faster at room temperature. The thermal solution is clearly designed to survive high temperatures and a lot of dust on the heatsinks. I also have a recent Keysight lab PSU. This one is whisper quiet and the fan only becomes audible under a considerable load. Personally I don't like to sit in an office with a lot of noise coming from fans. Whether you notice it or not, it does affect your thinking because your brains are busy filtering the noise away.

Replacing fans in existing equipment can be tricky. The replacement needs to provide the same airflow AND pressure. Noctua fans have a good name but aren't always the most optimal solution. There are many other fans out there which offer better airpressure at lower RPM by using more blades and/or by using a thicker frame.

I spend quite a bit of time making a Lecroy Wavepro 7k series quieter. I found a couple of rather exotic (and obsolete) fans that offer the same amount of airflow / pressure but make about 6dB less noise (which is significant). Using the service menu I could monitor the temperatures of various parts and compare the fan performance and thus make sure that the new fans offer at least the same amount of cooling.

But in the end low noise starts with a well thought out thermal design that includes things like directing the airflow. I have a Dell workstation which is whisper quiet due to the airducts that direct the airflow to the places where it is actually needed. The Lecroy Wavepro 7k OTOH has no airflow design at all so it needs a crapload of air and a lot of it goes nowhere.
Anthocyanina:

--- Quote from: balnazzar on October 07, 2022, 11:47:44 am ---One thing that may be of interest.

The AD2 also has the 'no zoom out' issue, exactly as the Siglents and many other scopes.

--- End quote ---

Isn't the zoom out thing with siglent that it will just capture however many samples are on the screen and not let you zoom out if you stop the acquisition?.

If that's it, then the AD2 doesn't do it. It lets you zoom out, but what limits it is the sample memory. As long as you're sampling at 100MSPS and have configured it for 16384 points for the scope, you'll be able to get 163microseconds of record, even if you stopped the acquisition at the fastest timebase. When you are sampling at a slower rate, it's because now it needs to reduce the sample rate to fill the sample memory, and at some point, it will be just enough to fill the screen.

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