While changing the frequency of HB-100 10 GHz radar modules is pretty simple, it is not so easy to understand where exactly it has been set. Unless you have got access to an expensive frequency counter, of course.
A common workaround seems to be using a satellite TV LNB so that the whole 10 GHz band is downconverted below 2 GHz, which is more affordable to be measured even with an RTLSDR dongle! As long as everything sits in the same room, there should be enough signal to do meaningful measurements.
I need to dig out one of those LNB's and do some cut and solder.