I have not used a 5V to 12V boost converter, but I have added a couple diodes to my QDX to pull 5V from the QDX USB data port and apply it to the +12V and VCC rails to power the rest of the radio. Since the QDX transmit power is relative to the input voltage, powering it will 5V results in about 100mW of transmit power. I have made contacts at 1000 miles using JS8Call with this modification. Powering the QDX with 5v has been discussed in other posts in the past.
BE AWARE! There is a known "issue" with the QDX switching regulator when rapidly transitioning from a lower voltage to a higher voltage (i.e. connecting 5V from the USB and then 12V) that will destroy components due to over voltage. Always connect power first before the USB cable after making this modification.
