Here a second option that does not require a spectrum display, in this method you will be using your ears instead of your eyes. This is now it works, and also why...
- pick a broadcast station or timesignal with proven stable frequency
- switch to USB (you should now here a 2kHz tone, that would be the carrier)
- set the dial 2kHz above the nominal frequency (this bring you close to zero beat)
- adjust the clarifier for zero beat
This is why this works, the HF3 has got a very wide side-band filter, I guess that saves the maker some money. Hence, the filter's passband is broad enough to even pass the carrier and LSB contributions, allowing us to adjust the clarifier w/o any further tricks.