Topband: Formula

[Jim Clymer]

Do you have an antenna analyzer that measures the inductive reactance? That
would be the easiest approach.
Jim - WS6X



Today's
Date: Sun, 10 Dec 2017 16:05:53 -0500
From: "Gary Smith" <Gary at ka1j.com>

I just installed a replacement wire for
the 160 sloper. I made it 129' as was the
earlier one that came down in the winds. I
have to use a spud gun to get fishing line
over the tree tops and where the spud
lands, I connect the wire to the eye
fastener & reel it to the radial plate.
This time I had to use a different tree as
the earlier one came down in the last
hurricane.

Now it is resonant at 1.785 and it is not
a problem at the lower end of 160 but
higher up it is. My problem is compounded
in that I also use this antenna for 10M,
12M and the upper part of 15M. I need to
shorten it for use on these as well.

It is too far away to shorten the wire and
solder a new eye on it and now it is too
cold to play with it on the tree (have
difficulty walking right now). So being
too long, capacitance at the feed point
might be my best answer. I have several
fixed vacuum & doorknob capacitors of
small pF to choose from that I can put in
line. Is there a formula that I might plug
data into to come up with the needed pF?

Thanks & 73,

Gary
KA1J