Hi @mportnoy! Welcome to the forum! The FR test uses a chirp which can show erroneous results at the edges. The stepped tone @VAR showed is what you want.
it is often best to start at a single frequency and verify things are working as expected. For example, if you test at 1 kHz. are you seeing the turns ratio manifest as expected? You can also look at the time domain and verify you see the lead/lag that you expect. And then move to 10K, 20K, and then down to 20 Hz.
When testing with discrete tones, you can use the “IDLE GEN” button to generate a fixed tone, and that let’s you probe with a scope to verify the lead/lag, and also a DVM to probe the in/out numbers and confirm what you are seeing.
And once you have verified the single tones are making sense, then moved to stepped tones and verify the stepped tones at the discrete frequencies you measured are making sense.
And once the stepped tones are making sense, then you can move to a swept response. The swept response will be more sensitive to various settings (eg FFT size, input levels, etc).
At each step you’ll learn what settings matter (eg FFT size, minimum levels, etc) and can fold that knowledge into the next steps.
The good news is that, while it’s hard to debug this stuff in the frequency domain, you can always pus the TIME button to get to the time domain and that will quickly explain a lot.
So! With the above said, if you make a single measurement at 1 kHz using just a tone does it yield the result you’d expect? How about at 20k and 20 Hz?
Feel free to ask a lot of questions, no matter how basic.
I can’t figure out how to expand the FR measurement window past 20kHz.
To measure past 20 kHz, you’d first want to make sure you are running at 96K or 192K sample rate. The FR will automatically adjust the sweep for the higher sample rate. If you click on 192K and then right click on the Frequency Response button, you get the context menu. In there you’ll note the ending frequency of the sweep is 96K, and the sweep spans 10 octaves (93 Hz start).
And if you want to change X axis end frequency, you can right click on the X LOG button and change it to 100k, for example.