Topband: Inverted L in contact with leaves

[Mike Furrey]

 My inverted L with elevated radials has touched limbs and leaves and I have still gotten out well. SWR does change (but not appreciably) with the rise and fall of the tree sap and with rain (very wet tree). All were made of 14 gauge insulated wire from the big box hardware stores. The only issue (really excited the neighbors) occurred when a squirrel bit through the insulation at a high voltage point and the bare wire touched leaves. I had arcs and small flames occurring every time I hit the key.

73, Mike WA5POK


     On Thursday, August 29, 2019, 12:19:40 PM EDT, AB2E Darrell <ab2e at hotmail.com> wrote:  
 
 Hi Pete,
No effect noticed here for leaves with L wire running over tree.
I just reinstalled my 160m Inverted - L on a taller tree (fed 10ft off ground, 80ft vertical , about 52ft horizontal). It's been up all summer with leaves, it goes over the top of 95ft oak. My vertical wire is #12 THHN, insulated solid copper. I have 5 tuned radials of the same wire, but thinner gauge is also OK. I feed it with a 1:1 Balun Designs balun. I trimmed it slightly but it resonates about 1845 and gives me all the CW band. Tested with Acom 2000A at 1500W out....seems very stable as before mounted on a  shorter tree at about 65ft.

Pete, even 1 tuned radial for your L, you should see it working and loading up OK if you want to test.

I used to easily find the tech supplement online from Butternut for tuned radials, but it looks like it's now gone.
Check this document out https://rudys.typepad.com/files/elevated-ground-systems-article-final-version.pdf . N6LF did some modelling and looks very similar to ON4UN's conclusions in his lowband book that 4 tuned radials achieve 60% of the efficiency of 100+ radials on the ground. Some may dispute this, but I've never had enough real estate to put down a full ground radial field of 100+, but I do have room to put up 4 elevated radials. They can slope, go up and down but if you can, mount them about 10ft above ground.
The tuned radials are about 3.5% shorter than the 1/4wave element (see the formula). I cut them all the same as the element, and then gradually shorten them to adjust for resonance, depending on how the SWR looks.

In the past, the L has worked great for me. I now have about 115 countries confirmed on 160, all with an L.

73 and best of luck with the project,
Darrell AB2E


________________________________
From: Topband <topband-bounces at contesting.com> on behalf of N4ZR <n4zr at comcast.net>
Sent: Thursday, August 29, 2019 11:23 AM
To: topband reflector <Topband at contesting.com>
Subject: Topband: Inverted L in contact with leaves

My inverted L is taking shape - about 60 vertical, the rest horizontal.
For a couple of months anyway, it is touching a number of leaves in the
vertical section.  I assume that's not a concern, but thought I'd ask
before I get a lot of radials down. First short radial is down and
MFJ-259 results look promising.  It's just a problem of waiting for lawn
mowing to stop hi.

--

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
_________________
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector