Some time ago I was looking for a (cheap) solution to test and tune some RF filters. Having a SA without tracking generator I thought, how hard can it be to make a simple tracking generator. Not hard at all, I found out, if your SA has an LO output, typically the 1st LO.
http://www.kerrywong.com/2016/01/10/building-a-tracking-generator/ and some videos on youtube.
But my SA doesn't have it so, that's it...or is it?
I also have one of these relatively cheap windfreak RF generators
https://windfreaktech.com/product/usb-rf-signal-generator/Well, not exactly that one but an older version of that one. This generator can do freqency sweep.
So I thought, what happens if I set the generator to do a sweep and enable the MAX HOLD on the SA.
Below is the response of a band pass filter. The first picture is the straight through connection between the generator and the SA, pretty flat, there's no need for normalization. The second picture is the filter response. Pretty sweet...
Sure you'll have to wait 2 - 3 minutes, it is not easy to tune a filter with it but it is doable.