Do I need to buy an LO amplifier to make external mixer measurements on a PSA Series Spectrum Analyzer (E4440A, E4446A, E4448A) and under what circumstance would an LO amplifier be required?
Under normal operating conditions using a 11970 or 11974 Series harmonic mixer, an LO amplifier is not required.
There are situations where an LO amplifier may be required. These situations include using third party mixers, which may require a higher level of LO, or if the harmonic mixers are placed at a long distance from the LO port on the PSA. Cable loss may need to be compensated for.