Comment by jdietrich

>since USB Power Delivery can supply 20V at 5A, might USB serve as a standardized power source for radio amplifiers?

Probably not. A typical amateur transceiver draws about 300W on transmit, which massively exceeds the 100W limit of USB Power Delivery. A linear amplifier running at the American legal limit will draw as much as 3.5kW.

The de-facto standard for mobile equipment is 13.8v DC +/- 10%, which allows for operation on standard lead-acid batteries.