Larry wrote:
>The small square image on the web site you pointed to looks like
>a split ground wire bolt. I have not seen them as galvanized before
>but they are readily available in several sizes in brass in the electrical
>departments of places like Home Depot and Lowes. I suppose it
>is the "No image" pieces you were really pointed at.
>
That's correct. The missing image is of a pair of square plates in
galvanized steel, that bolt together with interlocking fingers to make
crossover connections. They're just perfect for the stock fencing that I
described, with its large square mesh.
The galvanized split bolts are OK too, but better suited to individual
wires.
>Several years ago I used galvanized chicken wire mesh radials during
>the winter months so they just sat atop the ground. They seemed to
>improve operation but I didn't do any scientific study. The mesh I had
>was about 24 inches (60cm) wide. I used aluminum strips with several
>bolts and Noalox at the antenna end of the mesh. I just rolled up the
>mesh in the Spring,
I do the same. One final session with the mower, and it'll be time to
roll them out again.
73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
>
>73, Larry W6NWS
>----- Original Message -----
>From: "Ian White GM3SEK" <gm3sek@ifwtech.co.uk>
>To: <towertalk@contesting.com>
>Sent: Friday, September 23, 2011 3:53 AM
>Subject: Re: [TowerTalk] low band antenna without good ground
>
>
>> Alex K2BB wrote:
>>>I cannot add more wire radials - there are 3 radials already each way
>>>from the tower, 3 feet apart.
>>
>> With so little ground area, you'll need to try much harder than that -
>> but believe me, it WILL be worth it.
>>
>>>I remember reading about some aluminum "chicken mesh" used as radials.
>>>I think it might help. Where do I get it?
>>>
>>
>> Broad strips of radial material will definitely be better. Probably the
>> key reference is still the article by Robert Sherwood (yes, *that* Rob
>> Sherwood) in Ham Radio, May 1977.
>>
>> But don't use chicken mesh of any kind! It's great for expeditions and
>> Field Days but in a permanent installation it will break up in the
>> ground (a former owner of this house had kindly left some test samples)
>> and will be a nightmare to remove.
>>
>> I'm having much better experience with heavyweight galvanized "stock
>> fencing", about 3ft wide and divided into 6in squares which are plenty
>> dense enough for HF. This is much stronger and more heavily plated than
>> chicken mesh, and surprisingly it was also cheaper.
>>
>> Although galvanized steel cannot equal traditional copper wire for
>> conductivity, the losses are more than offset by the greater ground
>> coverage. (Remember also that the skin effect concentrates the RF
>> currents into the more conductive zinc plating; and because it's a mesh,
>> the current density in the individual wires is quite low.)
>>
>> For connecting the strips of fencing together at the base of the
>> antenna, these 4-way clamps proved to be ideal (sorry, there seems to be
>> either no image or the wrong image for this product):
>> <http://www.rappa.co.uk/products/151-four-way-line-clamp-25-pack>
>>
>> There's sure to be something similar at your neighborhood NYC farmer's
>> store.
>>
>>
>> --
>>
>> 73 from Ian GM3SEK
>> http://www.ifwtech.co.uk/g3sek
>> _______________________________________________
--
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