I understand where you are coming from on the robustness of the #16.
Originally I was concerned too. However this is the second vertical I
have used it on and had the wire down for several years without any
problems. Starting at the base of the vertical I just wrap the wire
around the head of a 8" long nail spaced approx. every 15ft,(depending
on the lay of the land), along the length of the radial and drive the
nail into the ground to hold the wire down. Then over one summer the
grass grows over the wire and will hold it down very well.
Dan
WD4LUR
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Rob Atkinson,
K5UJ
Sent: Wednesday, June 14, 2006 12:47 PM
To: schiers@netins.net; towertalk@contesting.com; jimlux@earthlink.net
Subject: Re: [TowerTalk] re Radials
the davis RF price for #16 looks pretty good by current pricing however
I am
a bit leery of the physical robustness of #16.
WOR reportedly tried aluminum at one time and it didn't work out for
some
reason. Maybe the Al didn't last.
you might think $68 for 1K' isn't bad but if you are putting down 100
1/4 w.
radials for 160 it starts getting pricey for a ham. do the arithmetic.
re the 20' radials--a base fed linear conductor perpendicular to earth
comes
under the effect of earth when close, so that earth becomes the mirror
part,
or the missing other half of the radiator. the massiveness of the
earth
predominates so that any radials buried or laid on the surface aren't
the
"mirror part" so much as they facilitate earth return conductivity by
helping overcome resistance of earth ground. Because of that their
length
isn't quite as critical. If you could levitate the radiator up into the
air
to sufficiently isolate it from earth's surface, then any metal
component
(we'll continue to use radials) intended to be the lower half, or
mirror,
must perform all of the counterpoise or groundplane function and because
it
is a complete antenna component, its length matters. This is why if you
place your radiator up say, 10 feet on 40 m. the radial lengths have to
be
measured and cut appropriately.
Studies (I know of at least one IEEE paper on this) have shown that
unusually short radials on the ground or below grade work almost as well
as
1/4 or 1/2 w radials, but in this case, "short" meant 45 degrees or 1/8
w.
I think 20 feet is pushing the short envelope. Also, it is critical
that
you employ lots of radials to enjoy the benefit of having them. Five or
ten
or twenty is not enough. From what I have read, if you put down ninety
radials around 60 feet long, you will enjoy almost the same field
strengh in
mv/meter at one km you would have with the same number of radials 1/4 w.
long on 160 meters. Most hams who find ground mounted verticals to be
poor
performers simply do not use enough radials.
rob / k5uj
From: "hasan schiers" <schiers@netins.net>
To: "Rob Atkinson, K5UJ"
<k5uj@hotmail.com>,<towertalk@contesting.com>,"Jim
Lux" <jimlux@earthlink.net>
Subject: Re: [TowerTalk] re Radials
Date: Wed, 14 Jun 2006 09:13:21 -0500
But....aluminum in a lot of soil types will disintegrate in a couple of
years, so best to know the soil characteristics before making the effort
to
lay a bunch of aluminum down. 68 bucks for a 1000' of #14 THHN insulated
copper wire is not a fortune, and would last a very long time.
73,
...hasan, N0AN
----- Original Message ----- From: "Jim Lux" <jimlux@earthlink.net>
To: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>; <towertalk@contesting.com>
Sent: Wednesday, June 14, 2006 8:56 AM
Subject: Re: [TowerTalk] re Radials
>At 06:29 AM 6/14/2006, Rob Atkinson, K5UJ wrote:
>>It depends on whether or not you either bury them, lay them flat on
the
>>ground or elevate them a significant distance in terms of wavelength.
If
>>you bury them or lay them on the ground the 40 meter 1/4 w/l will be
okay
>>on 20. If you elevate them (for 7 mhz 6 feet would probably be okay)
then
>>I think you need radials cut to each band you want to operate.
>>
>>If you haven't bought your wire yet, you'll have to rob a bank first.
I
>>heard last night that #14 and #12 cu wire prices have gone to the
>>moon. A guy I know paid $90 for 500' of #12 at one of the big box
>>stores. 500' of #14 is around $40. It was $15 two years ago.
>
>
>Yes indeedy.. copper prices have shot through the roof. Starts to make
>aluminum electric fence wire look more attractive. 60% of the
conductivity
>of copper, but less than half the price, so just lay twice as much.
(Labor
>is free on ham antenna projects, right?)
>
>
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