Andrew
Thank you for the reply.
I did try the audio modulation and zero span options but could not find away of averaging noise over a suitable period.
To measure a noise figure under the Y factor method you need to measure a change in the noise floor when you switch on a calibrated noise source. I use a 5dB excess noise reference source so I am looking for about a 6dB change with a low noise amplifier and less with a noisy one. Spike gives the expected result using an ordinary sweep with suitable bandwidth but it is not as easy to use as the measurement receiver utility in version 2.18 software which reports the change directly.
Has anybody else used a SA44B to measure noise figures and if so how?
Richard