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Re: Topband: intersecting ground radials

To: "Bob Kupps" <n6bk@yahoo.com>, "topband" <topband@contesting.com>
Subject: Re: Topband: intersecting ground radials
From: "Tom W8JI" <w8ji@w8ji.com>
Reply-to: Tom W8JI <w8ji@w8ji.com>
Date: Tue, 18 Sep 2012 07:59:29 -0400
List-post: <topband@contesting.com">mailto:topband@contesting.com>
Hi I would like to place monopoles for 160 and 80m bands 30m apart causing their ground radials to intersect. The radials are #20 bare copperweld (since I happen to have 4000m) that would be laid out on top of the soil before turf was placed on top. These antennas would be used for transmitting only and never at the same time. Is it necessary to solder the intersecting wires together where they cross for any reason like they recommend for phased arrays? Naturally I hope not...>>>>

They either should be soldered together, or well separated. The last thing any of us want is a poor connection. A poor connection can make RF noise or rectify and mix signals, and a close spaced connection can arc and make a heat source that literally can cause wires to blow apart in lightning hits.

I hope you are not in an area of severe lightning if you are going to use #20. While I get away with #16 without any issues at all in repeated direct lighting hits, I would not risk #20. Maybe if you had many radials #20 would work, but otherwise there is some danger you could reach the fusing current limit.

Fusing current of #20 is 58 amperes, which is half of #16 and one quarter of #12 AWG copper. I use a minimum of 30 long radials of number 16 and have no problems with lighning melting wires **IF** they are not laying on other conductors with poor connections.

I left a piece of guy strand laying on the ground below a tower, where it crossed both a large heliax cable and a wide copper flashing. After a strike or two I found it had melted the wide flashing and blown a hole through the heliax jacket. I sure learened a lesson on "close but not bonded" conductors!

My arc welders don't melt the very thin welding wire except at the arc point. :-) My experience is this carries over to unintentional arcs.

73 Tom
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UR RST IS ... ... ..9 QSB QSB - hw? BK

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