The best NF at SA44B input I have got is about 10 dB for 1000 MHz and somewhat better for 145 MHz (8.5 dB). The double power method was used too. The LabVIEW tools were used (not the Spike software), special procedures of noise measurements were composed, needed number of samples for predefined averaging accuracy was calculated a priori. The reference level set was -60 dB for best results received.
Unfortunately, an attempt to set attenuation or to switch on the preamp by LabVIEW function failed.
Regards,
Dimitry, UA3AVR.