EricZenviewStud
Member
Is it possible to use a regular passive oscilloscope probe with a spectrum analyzer?
Obviously the answer is NO , to obtain something useful you need first to measure the impedance of your spectrum analyser….
Looking to do this for my older generation QA400 audio spectrum analyser, I first found this link , an helpful explanation with some pictures.
https://www.rigol-uk.co.uk/page/2/?m=0
So I went to build my first one with a resistor just added, while it was somewhat « useable » but some noise degradation was evident…
I then went on, to modify old cheap scope probes x1/x10 into a x10/x100 probe for my QA400.
Results in the audio band were much better, my initial analyser dynamic range no probe attached ie loop back mode of 105,1 db went down only to 103,6 db probe attached no signal fed…
Finally loop back mode test showed still better results of 104,8 db closer to the analyser actual direct loop back results…
Here are my two videos on the making:
After further testing here are the final more precise results comparing « resistor » made probes and properly shielded ones…
Here the Link to the second video and the results
Obviously the answer is NO , to obtain something useful you need first to measure the impedance of your spectrum analyser….
Looking to do this for my older generation QA400 audio spectrum analyser, I first found this link , an helpful explanation with some pictures.
https://www.rigol-uk.co.uk/page/2/?m=0
So I went to build my first one with a resistor just added, while it was somewhat « useable » but some noise degradation was evident…
I then went on, to modify old cheap scope probes x1/x10 into a x10/x100 probe for my QA400.
Results in the audio band were much better, my initial analyser dynamic range no probe attached ie loop back mode of 105,1 db went down only to 103,6 db probe attached no signal fed…
Finally loop back mode test showed still better results of 104,8 db closer to the analyser actual direct loop back results…
Here are my two videos on the making:
After further testing here are the final more precise results comparing « resistor » made probes and properly shielded ones…
Here the Link to the second video and the results
