Topband: about beverage lenght

[Jorge Diez - CX6VM]

Hello,
in the beverage feedsistem by DXEngineerring manual says about the best
lenght for 160 mts beverage is 720 fts. just want to confirm in the
practice that this is the best lenght or is there any other
recomendation.
 
Maybe a reasonable lenght to be use together for 160 and 80 mts?
 
My idea is to put to equal beverage, one to US and another to Europe.
Basically, the both will start in the same point, like a inverted V. is
there any problem that the 2 beverages where close in the side where the
coaxial is conencted?. Maybe 3 feets, or is recomended to be more apart
one to the other?.
 
May i use the same ground sistem for both bv´s or is better to have them
separate?
 
may i use the same coaxial to go both bv´s to the shack? Maybe something
with a small relay box to switch between the bv´s... Or is better to
have independent coaxial for each one?
 
thanks!
73,
Jorge
CX6VM