I played with the device today, it probably works 100%, I tested the generator and the analyzer in FFT mode, and the observed spectrum is ok between 0 and 80 kHz (perfectly pure and amplitude ok (from 10uV to 20V). The noise is -120dB from memory.
For these tests I connected the generator output to the analyzer input with an XLR cable. The amplitude and frequency measurements matched perfectly. With modulated signals, we observe spectral lines which correspond to the modulations.