Topband: Decoupling Elevated Radials on 160M

[Phil Clements]

>Maybe easy, but decoupling is still necessary if you want a 
>clean and reliable installation. The notion a few 1/4 wl 
>radials result in a perfectly unbalanced antenna is clearly 
>false.

>A commercial 40MHz groundplane using four 1/4 wl radials 
>required significant choking (a few hundred ohms CM 
>impedance) of the feed line shield *and* isolation of the 
>radial common point to the mounting bracket. Without doing 
>that common mode current was so bad SWR could change from 
>1:1 to 2:1 just by altering the height of the supporting 
>mast or length of the feed line.  The problem also applies to 
>160 meter verticals as well as UHF ground planes.

>With elevated radials near earth there can be a dB or more 
>FS reduction when the feed line shield is not decoupled.

>Tom

My feed line choke is 24 turns of RG-8 on a 6 inch PVC pipe. It is located
right at the feed point, 60 ft. up the tower.

Is this sufficient, or do I need something more?

(((73)))
Phil, K5PC