The timing of this topic couldn't be better. I was doing some major
rework on my 80M vertical this weekend. The old style radial system
consisted of radials made from insulated wire with a chicken wire ground
screen layered on top.
I've often wondered if it makes any difference if the ground screen is
on top of the insulated radials or if the radials can be on top of the
ground screen?
Since the radials are insulated, should they be bonded to the ground
screen anywhere besides at the base of the antenna?
BTW..at my QTH in SE Wisconsin, the galvanized chicken wire survives the
elements quite well. About three years ago I was at Home Depot and they
happened to have a special on 25 ft rolls of 2 ft wide chicken wire. I
figured, what the hell and bought 4 rolls. I also bought some
galvanized steel "strapping" which consisted of a 4 foot long piece of
~1 1/2" flat stock with 5/16" inch holes every 3/4". I cut these into 2
foot long pieces to match the width of the chicken wire, folded over the
chicken wire several times and sandwiched the folded chicken wire
between the two pieces of strapping and bolted the strapping , with the
chicken wire in between, together. Before assembling the "sandwich" I
liberally gooped everything with Penetrox.
Then I bolted the sandwiched chicken wire to my radial plate and rolled
the chicken wire out on top of the insulated radials.
Does it work? I can't answer that scientifically but I can say that the
bandwidth of my antenna narrowed a little. Meaning I'm heading in the
right direction.
Today when I rolled up the chicken wire after three years it was almost
like new, still shiny. Despite being in the woods, covered with grass,
leaves twigs, etc and getting rained on and covered with snow every winter.
On 9/4/2011 1:50 PM, ZR wrote:
> ----- Original Message -----
> From: "Herb Schoenbohm"<herbs@vitelcom.net>
> To:<topband@contesting.com>
> Sent: Saturday, September 03, 2011 4:30 AM
> Subject: Re: Topband: Fence "ground screen" instead of wire radials?
>
>
>> On 9/2/2011 6:06 PM, Brian Machesney wrote:
>>>> Thanks to NI0C for reminding me that this info was presented by NC0B
>> Chicken wire or rabbit wire make an inexpensive alternative to an
>> expanded copper mesh ground screen. Just roll it out in multiple
>> directions from the tower base and tack it to the ground on top of the
>> grass. The grass will grow through it in a short period and it will be
>> invisible. that is easier than rolling up the sod for sure. The only
>> problem is the connection but since the actual tower is most likely
>> galvanized steel there isn't an issue of dissimilar metal just figuring
>> out how to making a convenient connection via a galvanize steel bus with
>> similar jumpers to the actual tower. Soldering is not possible and cad
>> weld is expensive. Tinned copper braid jumpers with the proper
>> preparation can work and galvanized steel angle brackets as well.
>
> I used 4' x 50' rabbit mesh (2x4") that was welded, then galvanized and then
> plastic dipped for over 10 years at a prior QTH. It was purchased that way
> at a garden store.
>
> Galvanizing is very easy to solder to with just normal rosin solder and all
> I did was run some stranded #12 copper to the #6 copper ring at the base of
> the shunt fed tower. A bit of spray autobody undercoating sealed the mesh
> solder connections.
>
> Prior to this there were 60 radials, 60-135' long and performance was fair.
> With the 4 sections of mesh on top of them it became a pileup buster and
> contest winner.
>
> Carl
> KM1H
>
>
>
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
--
73,
Gary K9GS
Check out K9NS on the web: http://www.k9ns.com
Greater Milwaukee DX Association: http://www.gmdxa.org
Society of Midwest Contesters: http://www.w9smc.com
************************************************
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
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