It's easy to make a wide band scanner of your DR-620E:
By remove the cover, you see a blue wire. Cut this wire and reset your TRX (PWR-on + FUNC).
Now you get the following frq. range:
76-108 mhz wfm only RX
108-136 mhz AM only RX
136-174 mhz FM RX and TX
400-480 Mhz FM RX and TX
800-999 Mhz FM RX
334-400 Mhz FM RX
To switch between bands use F and the CALL keys.
You can RX also on every band in AM by holding the F and pressing the LOCK keys.
Use pwr onn together with V/M button, stop it by pwr on/off