Without getting into the measurements - I think you need to detune the
tower if that is going to work at all. Probably put a trap in the bottom
20 feet.
Tree N6TR
On Thu, Dec 21, 2023 at 6:27 AM Noel Lopez via Topband <
topband@contesting.com> wrote:
> Here is my 2 cents worth. First of all, I am not an antenna expert nor do
> I know how to use antenna modeling software.These are my thoughts based on
> my experience and what I remember reading. My low band system is an
> inverted L under a SteppIr yagi that can be retracted. This avoids the
> capacitance hat effect on the inverted L.
> The capacitative top hats you have on your tower make the inverted L
> "appear" longer thus requiring morecapacitance to match the inverted L.
> If there were no yagis to create capacitance over the inverted L,
> the antenna would appear shorter and require less capacitance to match.
> Capacitative matching is less lossy and more efficient than inductive
> matching from what I remember.
> I am posting this to see if anyone can add-to or correct my comments.
> Noel Lopez NR5R
> On Wednesday, December 20, 2023 at 07:52:00 PM CST, Steve Muenich <
> srmuenich@gmail.com> wrote:
>
> I have an Inverted-L question that hopefully someone can answer for me.
>
> I installed the 160m wire to the 80 ft level on a 100 ft Rohn 45 tower
> with top mounted yagis.
> The horizontal (sort of) portion is approx 45ft long.
> The wire starts at 80 ft down approx 5 ft from tower and when it gets to
> the match box the bottom of the wire is about 10ft away from tower.
>
> I have about 50 or so 120 ft long radials.
>
> I am able to get a X=0, R=52. SWR 1.19:1 tune according to my RE Zoom using
> load shunt match at base of tower.
>
> My question is why do I need so much series capacitance (5300pf) with
> parallel inductance approx 8uh?
>
> Everything is working fine, but I am wanting to understand why I am needing
> so much series capacitance? Does this indicate an issue I need to resolve?
>
> TIA,
>
> Steve, NA5C
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