Spectrum of signal

I have a 40 MHz pulse signal.

How to do a basic spectral analysis on this ? I mean by measurement.

Just put a spectrum analyser at the output?

For spectral analysis of a pulsed signal is good to use the Spectrum Analyzer in Zero Span mode, and check for spectrum emissions at different frequencies from the carrier. Have to trigger also the SA, using external or video trigger.
The RBW of the analyzer is important for accurate measurements, and this depends by pulse timing.