I have a friend who has a DSA90604A and wants to go sniffing for EMI issues. I suggested that he get some Beehive probes (although he could clearly afford better). Questions:
1. Can the DSA90604A be used as a sniffer or is a real spectrum analyzer needed?
Well, it does have pretty good FFT but at the end of the day it's an 8bit scope so it has very limited dynamic range. But yes, it is possible.
2. If the DSA90604A can be used, will it need a preamp to go with the probes?
I don't know, that depends on what level of emissions he expects and the sensitivity of the probes (which I don't know).
3. He also has a Tek TDS5104B but I think that can't do the job, am I right?
The TDS is pretty old and slow, and if I remember right FFT was an option and was pretty poor even by the standards back then.
Thanks in advance for any comments, input, or advice
Well, the fact that he considers a 1GHz Tek antique tells me that 1GHz BW is enough, so depending on how often this is needed it might make sense to just buy some new entry-level spectrum analyzer like the Rigol DSA or Siglent SSA and be done with it.
If it has to be scopes, though, then the DSA will be vastly superior over the Tektronix scope.