Matthew:

There is no "humvee radio" as such. The radios installed in any military
vehicle depend on the radios used by the unit. Whatever radios are in the
unit's inventory are mounted in the humvee, duece, 5 ton, etc. Most units
don't have HF capability ( I used to be in a reserve unit that tried to
demonstrate the advantages of HF) so you mostly find VHF-FM radios of all
types and vintages from PRC-77& RT-524 to SINCGARS. Units install what they
have.

On the "worthless" RT-524...I once visited a 'retrans' site (
"retransmit"...Army equivalent to a repeater site) that was based on two
RT-524's, connected with a retrans cable, and two separate antennas about 50
feet apart. They had six RT-524's on site, to improve the odds of having
two that worked. The ones that were in service were shaded with tarps to
keep the sun off them and covered with wet towels to keep them cool.

Roger K6XQ