scope probe impedance for spectrum analyzer

[Gagan_SJSU]

Hi Friends

I was wondering what is the meaning of scope probe impedance of a spectrum analyzer and what is its typical value? And what is the difference between setting this impedance to 50 ohms as compared to when it is lets say 1Mohms?

please let me know

Thank you
Sunny

 

[pico]

The input impedance of the test instrument is the load of the device under test (DUT). So, if you want to load the DUT properly by using the input impedance of the test instrument as a load then you use the 50 ohm to match the DUT, but you should aware of the power rating (not to burn the input of the test instrument). This is called "terminating measurement". But, if the DUT is terminated properly before making measurement, so you should use the high impedance mode (1Mohms to measure the DUT) so that not to load the DUT. This is called "bridging measurement".

 

[davenn]

Hi Friends

I was wondering what is the meaning of scope probe impedance of a spectrum analyzer and what is its typical value? And what is the difference between setting this impedance to 50 ohms as compared to when it is lets say 1Mohms?

please let me know

Thank you
Sunny

The inputs to spectrum analysers are typically a choice of 50 Ohm or 75 Ohm
depending of its intended use, 50 Ohm comms industry 75 Ohms TV industry

If you was accurate readings from the spec an. Then you need your DUT output impedance to match the imput impedance of the spec an.

Using a scope probe isnt going to give you accurate results, only a rough indication of signal levels etc

Dave

 

[Gagan_SJSU]

Thanks Dave and Pico..thanks a lot for your help