Topband: Feedline isolation

[Milt Jensen, N5IA]

Greetings,
        I have a question for the all knowing.  I am helping a fellow ham
with a new antenna installation.  The design is to have an elevated 1/4 WL
160 M. vertical be comprised of 90' of tower over an insulated base at 30'
AGL with a Force 12 C4XL as a top hat.
        The question is:  What is the best way to isolate the two feedlines
coming from the C4XL, and the rotor cable, as they pass by the isulated
base of the 160 M. vertical?
        I have considered three possibilities, but have no practical
experience with any of the designs.  Also, I have been unable to find
anything in the literature that I have on hand.  So, your thoughts.

        1.  Install a string (50?) of ferrite beads over each of the coaxes
&             control cable at the insulated point to create RF chokes?

        2.  Wind 20 or so 6" diameter turns in each cable at the insulated
           point to create RF chokes?

        3.  Insert the coaxes (small teflon insulated variety as jumpers in
this             application) and control cable in a length of copper
tubing and wind             it all into an RF choke to bridge the insulator
gap?

        Or is there some better (cheaper, easier, more effective) way to
accomplish the desired choking of the 160 M. RF on the C4XL feedlines and
the rotor control cable such that they do not detune the 160 M. antenna?
        Thanks in advance for all the suggestions that I know will be forth
coming from the experienced masses.
                                                Milt Jensen, N5IA 



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