Hi Steve,
5300 pF is way large. It indicates *something *else is going on.
"Something" needs to be determined.
One thing for sure, after nearly a decade of correspondence with this as a
frequent subject, there is no one single "silver bullet" to fix this in all
cases. It is complicated and with s
Remember, Steve, for a given frequency more capacitance equals less
capacitive reactance [Xc = 1/(2*pi*f*c)]. At 1825 KHz, 5300 pf is only
16.5 ohms reactance. That means you are only offsetting a small amount
of inductive reactance. Where you should be more concerned is when the
series capacit
FWIW, for 160 I used my old 97-foot Rohn 25 tower, with 2 tribanders and
a 40M 2-el on it, shunt fed at about 50 feet. I had a pair of 300 uf
variable caps at the bottom, one in series with the feed and the other
in parallel. It proved to be easy to tune to low SWR once I discovered
that the
On 12/21/2023 12:54 PM, Paul Dulaff via Topband wrote:
Ran a basic EZNEC model with no tower present for your 80 ft X 45 ft
inverted L at 1.825 Mhz. The base impedance for this is 28.5 - j 130
ohms. The get rid of the reactance I extended the top wire an
additional 20 ft so 80 X 65 ft and base
Steve
Ran a basic EZNEC model with no tower present for your 80 ft X 45 ft
inverted L at 1.825 Mhz. The base impedance for this is 28.5 - j 130
ohms. The get rid of the reactance I extended the top wire an
additional 20 ft so 80 X 65 ft and base impedance is 37.2 + j0. The
tower is definitel
Steve,
For comparison my inverted-L is similar to yours with a 94 ft vertical
section and 43 ft horizontal (ish). It is on a tall tree, not a tower.
Like you, I use an L-network to match it and get a feed impedance on 1826.5
KHz of 50+j0. I have a 1600pF capacitor in parallel but no inductor as I
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
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 capac
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
th
On Tue,2/3/2015 1:55 PM, Art Snapper wrote:
How important is it for the top part to be led away at a right angle?
I was considering running it vertically 80ft, then about 25 feet at a 45
degree up angle and 25 feet at a 45 degree down angle, over the top of the
supporting tree.
That shape shou
The most important part of an inverted L is the counterpoise, be it raised
radials, buried or on-ground radials or an FCP. Be sure you can do a
counterpoise well. Otherwise the counterpoise can be a huge RF loss, easily
negating anything done well with the L wire itself.
Next the vertical part of
Art, from what I’ve read, I understand that the non-vertical part of the
Inverted L does not have to be completely horizontal - it can slope with little
detriment to it’s radiation pattern. I have two - one for 80 and one for 160.
Both of ‘em slope away from the top support.
Jim / W6JHB
> On
I have been looking at locations on my property to install an Inverted L
for 160.
How important is it for the top part to be led away at a right angle?
I was considering running it vertically 80ft, then about 25 feet at a 45
degree up angle and 25 feet at a 45 degree down angle, over the top of t
On Thu, Dec 27, 2012 at 10:12 AM, Ashton Lee
wrote:
> Several of us here in Western Colorado run slopers off the tower, which I
> believe is essentially loading the tower with an elevated lead. It works
> for us.
Sloper is really not the same thing as a parallel vertical wire at four
feet as w
On Wed, Dec 26, 2012 at 3:08 PM, Tom W8JI wrote:
>
> At any distance less than 1/4 wave or so, which is around 130 feet, the
> inverted L is coupled very tightly to the tower. At wider spacings, like
> 50-100 feet, the tower and things on the tower **sometimes** won't have
> much interaction. Of
- Original Message -
From: "Tom W8JI"
To: "Herb Krumich" ;
Sent: Wednesday, December 26, 2012 3:08 PM
Subject: Re: Topband: Inverted L question
I am right now using an inverted L which is spaced about 4 feet away from
my tower. The vertical leg is about 85
I am right now using an inverted L which is spaced about 4 feet away from my
tower. The vertical leg is about 85 feet. I only have 6 radials at the
present time
Now here is the question
The horizontal leg is about 50 feet and goes to my back yard. Since the
trees are not that high, it probably
Snip: I am right now using an inverted L which is spaced about 4 feet away
from my tower. The vertical leg is about 85 feet.
I remember a number of years ago talking with Jeff Briggs (K1ZM) about
ideas for my first inverted-L while we were both waiting for flights out of
the Dayton Hamvention.
ground system. 73 Clive GM3POI
-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Herb
Krumich
Sent: 24 December 2012 19:14
To: topband@contesting.com
Subject: Topband: Inverted L question
I am right now using an inverted L which is spaced about 4 feet
I am right now using an inverted L which is spaced about 4 feet away from my
tower. The vertical leg is about 85 feet. I only have 6 radials at the present
time
Now here is the question
The horizontal leg is about 50 feet and goes to my back yard. Since the trees
are not that high, it probably s
"and radial" is that really singular or a typo? 73, Guy.
On Mon, Apr 30, 2012 at 11:16 AM, Jim WA9YSD wrote:
> My feed point impedance with every thing grounded and measuring against
> the tower ground and radial is 27 ohms.
___
UR RST IS ... ... ..
I have been playing with and reading about inverted L, and verticals Since
November 2011. I had very little experience with them before that time.
I have the feed point mounded next to the tower where I could make measurements
and the sort. My feed point impedance with every thing grounded and
April 29, 2012 10:22 PM
Subject: Re: Topband: Inverted L Question - Reply
> The normal innocent presumption would be that your feedlines and other
> miscellaneous conductors are not involved in your patterns. But if your L
> and your 6BTV are engaged in a horse race on 160, your tower/L is reall
The normal innocent presumption would be that your feedlines and other
miscellaneous conductors are not involved in your patterns. But if your L
and your 6BTV are engaged in a horse race on 160, your tower/L is really
not doing well, and has the typical loss problems for that setup.
My personal i
ginal Message -
> From: "Lloyd Korb"
> To:
> Sent: Sunday, April 29, 2012 7:51 AM
> Subject: Topband: Inverted L Question - Reply
>
>
>> What is interesting to me is the fact that at times the L seems to have a
>> different polarity than the 6BTV. I can switch
- Original Message -
From: "Lloyd Korb"
To:
Sent: Sunday, April 29, 2012 7:51 AM
Subject: Topband: Inverted L Question - Reply
> What is interesting to me is the fact that at times the L seems to have a
> different polarity than the 6BTV. I can switch back and f
- Original Message -
From: "Mike(W5UC)"
To:
Sent: Sunday, April 29, 2012 6:55 AM
Subject: Re: Topband: Inverted L Question
> Good Morning Lloyd & All:
>
> You have described my 160 & 80 meter antennas almost exactly. The
> vertical part of my L is about
To everyone how replied to my Inverted L question, a big THANKS! I really
learned a lot from the replies.
I know that what I have is not an ideal situation for the Inverted L but
it's all I have available to me. I live on a very standard one third of an
acre city lot. My 60 foot tower is used t
Good Morning Herb;
In years past, when I was living about 30 miles north of Dallas, I had a
shunt fed tower, and it worked very well. However, when I tried the
same configuration here, I got my fanny kicked on a regular basis, and
that was why I decided to put up the Inverted L. Occasionally
Mike, You would be much better off by feeding the tower with a shunt or
cage feed. As K2AV so accurately pointed out...an inverted "L"
supported by a metal tower is not the answer for an efficient system on
160. With the amount of radials you have at the base you could do much
better by feed
Good Morning Lloyd & All:
You have described my 160 & 80 meter antennas almost exactly. The
vertical part of my L is about 3 feet away from the tower at the top,
and approximately 2 feet away at the bottom. I also have a 80 meter
vertical wire on the other side of my tower. The 80 meter wire
Hi, Lloyd,
Using an L with the vertical running next to a tower like that means that
your tower is FULLY coupled to the L as if they were both transformer
windings. The principal determination of performance in this situation is
the tower, not the L. You will find that all conductors on the towe
Hello, I have used an Inverted L, on 160 meters, for many years and have
always been curious if I am okay with my present spacing. The spacing
between the vertical portion of the L and my 60 foot tower is 18 inches.
The spacing was picked for the ease of feeding the wire at the base of my
tower.
Given that you have the 70-90 vertical rise as a given (not in play as
maybe or maybe not), what the shape of your L will do to
improve/worsen your signal will be overwhelmingly swamped (not close
at all) by what you do or don't with your counterpoise. Unintended
coupling of lossy ground by a dozen
By all means make the vertical portion as tall as possible, even if the
horizontal part slopes downward a bit. My 90 footer is really an "inverted J"
over a hickory tree with the horizontal part sloping downward at about 20-30
degrees angle it plays fine with 100 watts Better than my sho
Scott,
let's compare the radiation resistance of the three antennas at 1.8 MHz.
55' x 82' Inverted-L is 16 ohms
100' x 36' Inverted-L with the 36' wire sloping downward at 45 deg is 28
ohms
100' base-loaded vertical with 22 uH inductor is 18 ohms
The antenna with the highest radiation resistance
First year on Top Band and I have a question regarding my inverted L. I now
have it 55 foot vertical with the remainder horizontal with elevated
radials. It works well, but the neighbors will not be happy in the spring
when they come back to their summer cottages! Hihi. I am going to move it
to
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