Elecraft

Re: RF in the Trees [OT]

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Michael Walker

Re: RF in the Trees [OT]

I run the following antennas in some pretty serious forest, and I get great
results with them all:

- 160M Inverted L with elevated radials over Pine trees. The tree is
about 90ft tall and then the insulated wire loops over a branch
- 80M Vertical also will elevated radials (the rope goes over a branch
at 90ft)
- 80M V with the apex at 70ft over a single Pine tree
- 132ft Windom supported at both ends with a center support over
hardwood trees at 60ft.

In all cases, you have to be created to allow for flex as the wind blows.
It has taken some trial and effort, but you'll figure it out by watching
things move. Yes, you'll break it a few times, but eventually you'll come
up with a solution.

The worst case for moving resonance is the Windom, but that is easy to deal
with.

The 160M vertical varies is resonance point, but that is due to the ground
conductivity changing from winter to summer.

As I mentioned earlier, just do it. It will work.

I have used both air cannons and my quad copters to drop my lines in place.

Mike va3mw
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Re: RF in the Trees [OT]

The best trick I've found in dealing with moving trees is running the
line through a pulley down to a weight that is heavy enough to keep the
things reasonably taught. The trees can move all the want and the line
just rides on the pulleys.

Doug -- K0DXV

On 6/25/14, 6:51 PM, Michael Walker wrote:

> I run the following antennas in some pretty serious forest, and I get great
> results with them all:
>
>
> - 160M Inverted L with elevated radials over Pine trees. The tree is
> about 90ft tall and then the insulated wire loops over a branch
> - 80M Vertical also will elevated radials (the rope goes over a branch
> at 90ft)
> - 80M V with the apex at 70ft over a single Pine tree
> - 132ft Windom supported at both ends with a center support over
> hardwood trees at 60ft.
>
> In all cases, you have to be created to allow for flex as the wind blows.
> It has taken some trial and effort, but you'll figure it out by watching
> things move. Yes, you'll break it a few times, but eventually you'll come
> up with a solution.
>
> The worst case for moving resonance is the Windom, but that is easy to deal
> with.
>
> The 160M vertical varies is resonance point, but that is due to the ground
> conductivity changing from winter to summer.
>
> As I mentioned earlier, just do it. It will work.
>
> I have used both air cannons and my quad copters to drop my lines in place.
>
>
> Mike va3mw
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

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Fred Townsend-2

Re: RF in the Trees [OT]

In reply to this post by Michael Walker

Hi Doug:
I use a similar technique in suspending my antennas. I thought I would add some do's and don'ts. Like don't forget copper will stretch. I use 1 gallon paint buckets full of dirt for about 10# of weight on the pulleys. I suspend the rope in a tree yoke or a limb close to the trunk to minimize sway. Be sure there is pleanty of travel for wind storms.

The ends of the antenna are 'hotter' than the feed point so I like to clear the end of the antenna and the tree with at least 8' of rope. If I have a middle support I use a yard arm of at least 4'. If you are using an antenna like a G5RV, Windom, or zepp that uses a portion of the feed line as a match, don't forget that portion will be radiating too so keep it vertical and away from the tree.

I have found pine and eucalyptus trees to be the worst for parasitic absorption but I think that is largely a function of the volume of sap and water so the wetter the more loss and the further away you want to keep the antenna.

73,
Fred, AE6QL
,
-----Original Message-----

>From: Doug Person via Elecraft <[hidden email]>
>Sent: Jun 25, 2014 8:03 PM
>To: [hidden email]
>Subject: Re: [Elecraft] RF in the Trees [OT]
>
>The best trick I've found in dealing with moving trees is running the
>line through a pulley down to a weight that is heavy enough to keep the
>things reasonably taught. The trees can move all the want and the line
>just rides on the pulleys.
>
>Doug -- K0DXV
>
>

KB9WMJ

Re: RF in the Trees [OT]

One of my Elmers showed me another way.

Purposley choose the twig ends of the branch of a huge tree. Use this as
your center of the dipole, or whatever. Blow a line all the way over the
tree, and attach it to something other than the tree. Pull up the antenna,
and leave rope line going down from the center point. Once you get the
center where you want it, tie the dangling rope to something solid, like a
Land Anchor. Pull the other side and tie it down to something solid as
well, like another Land Anchor, or even the base of another tree.

Now your center point is suspended towards the outside of a tree branch, and
will not move up and down, as you have it anchored from above, and below
even when the wind blows. Use the ends of the antenna to stop the antenna
from moving side to side. The trick is not allowing the centerpoint to
twist before you get the ends stretched out.

Keith
KB9WMJ

----- Original Message -----
From: "Fred Townsend" <[hidden email]>
To: "Doug Person" <[hidden email]>; <[hidden email]>
Sent: Thursday, June 26, 2014 12:19 AM
Subject: Re: [Elecraft] RF in the Trees [OT]

Hi Doug:
I use a similar technique in suspending my antennas. I thought I would add
some do's and don'ts. Like don't forget copper will stretch. I use 1 gallon
paint buckets full of dirt for about 10# of weight on the pulleys. I suspend
the rope in a tree yoke or a limb close to the trunk to minimize sway. Be
sure there is pleanty of travel for wind storms.

The ends of the antenna are 'hotter' than the feed point so I like to clear
the end of the antenna and the tree with at least 8' of rope. If I have a
middle support I use a yard arm of at least 4'. If you are using an antenna
like a G5RV, Windom, or zepp that uses a portion of the feed line as a
match, don't forget that portion will be radiating too so keep it vertical
and away from the tree.

I have found pine and eucalyptus trees to be the worst for parasitic
absorption but I think that is largely a function of the volume of sap and
water so the wetter the more loss and the further away you want to keep the
antenna.

73,
Fred, AE6QL

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