Hello Giuseppe,
Yes, an external 5 volt supply will work. I have 2 QLG-1's and a QLG-2 and use external power (not supplied by my QRP Labs equipment) on them all.
For the QLG-1 units I use a 7805 voltage regulator IC to step down externally supplied 12 volts to 5V.?
--Al
WD4AH
