Products > Test Equipment
Siglent SDG1032 Amplitude not constant when sweeping
<< < (8/8)
newbrain:

--- Quote from: eTobey on May 22, 2024, 09:29:39 am ---I have now made a final measurement, using proper connection, and using the maxhold function.

It shows clearly a asymmetry and the amplitude varation over the sweep in great detail. Too bad, that the math dont work with zoom mode (all of them?).

--- End quote ---
Do I read it correctly that now, with proper cabling, the variation is about 50 mV from end to end of the sweep?
And the signal level is about 2 Vp (no measure, and graticule very faint)?
So ≈0.2 dB of change.
That's not bad in itself, and also in spec, from the datasheet:

--- Quote ---Amplitude flatness -0.3 +0.3 dB 50 Ω load , 2.5 Vpp, compare to 10 kHz sine
--- End quote ---
eTobey:

--- Quote from: newbrain on May 22, 2024, 11:39:10 am ---
--- Quote from: eTobey on May 22, 2024, 09:29:39 am ---I have now made a final measurement, using proper connection, and using the maxhold function.

It shows clearly a asymmetry and the amplitude varation over the sweep in great detail. Too bad, that the math dont work with zoom mode (all of them?).

--- End quote ---
Do I read it correctly that now, with proper cabling, the variation is about 50 mV from end to end of the sweep?
And the signal level is about 2 Vp (no measure, and graticule very faint)?
So ≈0.2 dB of change.
That's not bad in itself, and also in spec, from the datasheet:

--- Quote ---Amplitude flatness -0.3 +0.3 dB 50 Ω load , 2.5 Vpp, compare to 10 kHz sine
--- End quote ---

--- End quote ---

It is a 5.05 Vpp "amplitude", but this is at a limit, what i did not notice then. Have you read the details on the picture name? (I guess its a bad place for that?)

Amplitude flattness is measured on a fixed frequency? If so, it could be better, but i think its probably a differend rail that is used for that (2.5V vs. 5V), and that could be different.

newbrain:

--- Quote from: eTobey on May 22, 2024, 06:10:09 pm ---Have you read the details on the picture name?

--- End quote ---
OOPS! Totally missed the picture name.

Then I stand corrected. It's a 50 mV variation from 1 to 30 MHz on a ~2.5 Vp signal.
I.e, 20 x (log10(2.525 - 0.05) - log10(2.525) ~= -0.174 dB , a bit less than my estimation.

Kudos to the output stage designers in Siglent (or FW designers for the calibration table, or both).

But I think this is a good lesson for better probing, connections, and termination techniques.

Don't worry, we all were wet behind the ears, once: just three days ago a dear and usually really smart friend of mine was probing a small RF power amplifier prototype.
He sent me some screen capture - I could not understand what was happening - for me it had worked with no issue...
Then he casually mentioned that he was not using the probe spring.
"Oh, definitely do not use the alligator for RF or fast edged signals!"
"No worries, I'm not using that either!"
 :-DD
eTobey:

--- Quote from: newbrain on May 22, 2024, 07:45:04 pm ---But I think this is a good lesson for better probing, connections, and termination techniques.

Don't worry, we all were wet behind the ears, once: just three days ago a dear and usually really smart friend of mine was probing a small RF power amplifier prototype.

--- End quote ---

Indeed it is. Never thought that those kind of slow signal changes could have such a dramatic effect. Thought it would only be relevant for higher frequencies (> 60MHz) or digital signals. I also discovered today, that compensation is as important, while looking with 2 probes at a triangular wave and plotting the difference. If i remember right, it was even at just 1kHz.

I do not worry, i do learn (while trying it out mostly) ;-) There are some good videos about the gnd spring on youtube. It seems to me, more than for proper termination.
thm_w:
I would say many of the issues were scope/gen settings and not probing technique.
Remove the terminator and it should be flat up until ~20MHz.

Compensation is important at low frequencies, yes, it is called LF compensation sometimes https://www.electronics-notes.com/articles/test-methods/oscilloscope/scope-probe-compensation.php
Navigation
Message Index
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod