I would like to take a measurement with my spectrum analyzer off a 440 VAC power line. How can I properly divide down the voltage without filtering out RF signals?
I can't give you any direct advice on this other than to say if you do try something to be VERY CAREFULL, as this could happen to your very expensive RF frontend as well...
I would say that you should not measure directly on the AC-line. Normally this is done with a transformer and you can make one very easily by just winding a wire a couple of turns arround the AC-line that you want to measure on. Connect one end of the wire to the shield and the other to the coaxial inner conductor. In this way you don't have any electrical contact with the AC-line. (NB just wind your wire arround one of the phases and test with different number of turns.)
Attachments
I would say that you should not measure directly on the AC-line. Normally this is done with a transformer and you can make one very easily by just winding a wire a couple of turns arround the AC-line that you want to measure on. Connect one end of the wire to the shield and the other to the coaxial inner conductor. In this way you don't have any electrical contact with the AC-line. (NB just wind your wire arround one of the phases and test with different number of turns.)
Regards
Jens