GAP VERTICAL PHASED???

[pp5jr at pp5jr.ampr.org]

Hello all,
i have 2 Voyager DX ( GAP- vertical for 20-40-80-160), and i'd like some
information if is it possible to phased them on 80 and 160m.
If possible witch is the ideal distance between them, and witch is the cable
that i need to use. 
Secound question about this type of antena: If i put a lot of radials, for 160m,
for example, i will improve de gain?
Thank you for your coments,
best 73
Sergio  pp5jr also zx5j
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