That is just pure nonsense (the up vs down part). You can buy a 30W
(15V @ 2A) dc-dc converter for $62 from Mouser (search for
UHE-15/2000-Q12). The description says the input is 24V, but it really
is 9-36V, which should cover just about any battery you want to come up
with. The thing is 88% efficient and occupies 1.5 in^3. You can buy
lower power ones even cheaper. If that makes your 14V heart feel
better, go for it (it won't damage your radio).

Tom Seim
2G DG-400