Phil, Could you not remove the 60ft high guys for a test.
Replace them with four copper radials that are then cut to
resonate the whole array at 1830. Having found your new radial
length introduce insulators into your old radials at the correct
length. Leaving your complete system now resonate at 1830.
and no capacitors. 73 Clive GM3POI
P.S. I would be inclined to model it first to get the numbers near
On 1 Sep 2011 at 8:57, Phil Clements wrote:
> Much has been written about matching 160 meter shortened vertical
> antennas,
> but very little about 160 meter antennas that are too long. There
> were two
> great articles in the old "Communications Quarterly" in 1998 about
> elevated
> ground planes, but I have lost them over the years. My current
> system was
> built from these articles.
>
>
>
> The system here is a 195 foot Rohn 25 tower, with insulators at the
> 60 foot
> level. The five sets of guy wires are all insulated from the tower,
> and
> additional insulators along their length to be invisible to 160
> meter RF.
> The guys at the 60 foot level, just below the tower insulators are
> utilized
> as the radials that form the ground plane. They are 110 electrical
> degrees
> long. The system resonates at 1510 KHz, requiring a capacitor
> connected
> across the feed point. 600 pf brings the system into resonance @
> 1830 KHz.
>
>
>
> There will soon come a day when I will not be able to climb to the
> 60 foot
> level to adjust the matching capacitor when needed. The question is:
> Can I
> place the capacitor at ground level, connected to the original feed
> point
> via coax or open-wire line? Will this 60 foot line radiate? I do not
> want to
> upset the radiation pattern of the system. I tried a motorized
> vacuum
> variable several years ago, but it was a high maintenance item due
> to
> exposure to the elements.
>
>
>
> I am open to all suggestions; perhaps some brand new ideas will
> surface from
> all the expertise on this reflector! After 57 years on the air, I
> am still
> learning, and trying to make improvements here!
>
>
>
> Thanks in advance for any/all comments.
>
>
>
> (((73)))
>
> Phil, K5PC
>
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