I would run the ground to the battery.
Tom Rauch —W8JI— covers that one in a short article on his website.
The MARINCO 3% Voltage Drop Chart and k0bg on the subject of power wiring cover the rest.
There are some Power devices sorta guaranteeing
a set voltage. MFJ or WEST MOUNTAIN.
Wanting a giant amp ain’t really gonna do much for Eleven Meter AM/SSB mobile. IMO, 50W gets you all the base hits you want, but past 200W (true) ain’t any home run guarantee. 120-150W
is it.
Reasonable amplification goes hand-in-hand with reasonable audio filtration.
Hear, and Get Heard. The point to having both
is to overcome the deficiencies of other mobile units on the road.
Just the past week (escaping and now chasing this damned winter storm) there’s been much more than the usual CB chatter.
On a
daily basis I run into 2-3
BIG RADIOS!! that have pinholes for ears.
They’re worthless.
They don’t have a more difficult vehicle to work with, RX or TX.
They can’t hear farther than the barefoot guy.
So why can I hear them, but they not hear me?
(It’s not a problem that a 5% voltage drop remedy will fix.)
This is also not car audio driving multiple speakers with a concern about dynamic range (Saint-Saens Symphony 3; post-1964 “music” has no range). That’s a huge instant amp demand. I defy it’s the same.
An antenna system optimized for the band or bands (tuner included if multiple) is where the real work goes.
The vehicle can be improved over factory in some aspects, but it also
ought to have a separate dedicated battery for Radio. (Audio matters. Clean audio).
I’d be more concerned with the passenger compartment wiring distribution & harness than
where a central ground point should be located.
Almost any will do.
.