Topband: Feedline; to ground, or not to ground?

[Phil Clements]

I have read several recent posts lately about feedline chokes and grounding
on 160 meter ground plane antennas. This has left me confused!

 

My full-size G.P. feed point is 60 feet above ground. There are three
radials that slope down from the feed point to about 10 feet above ground.
The system is tuned to resonance by a 1500 pf capacitor in series with the
radiating element. The heliax is attached to the antenna through a 1:1
balun. The heliax run is 400 feet long. Right now, the outer conductor
floats all the way to the entrance panel @ the ham shack, where it is bonded
and grounded.

 

Some suggest that the heliax have a ground kit installed at ground level,
where the cable leaves the tower base, where there are three ground rods,
and 100 buried radials. This would result in the outer conductor being
grounded at 60 feet and 400 feet from the antenna. Before the expense and
labor of a grounding kit installation, I seek your guidance and expertise on
this situation.

 

My inclination is to leave everything as-is, but I wonder if common-mode
current is being re-injected between the feed point balun and ground level?
The heliax run is inside the tower. (Rohn 25) I think that this provides
some additional shielding , but would strapping to ground at the base have
any advantages?

 

Many thanks in advance for your comments and advice!

 

(((73)))

Phil, K5PC