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From: "captbrian" <captbrian@ukonline.co.uk>
To: rsgb_lf_group@blacksheep.org
Date: Wed, 9 Jul 2003 15:02:45 +0100
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Subject: LF: Re: re Earth losses
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1) every time I  have a good idea some other B(oy) thought of it first.

2)  Did Finbar's wire replace or supplement the real earth?

3) If you only had a given amount of wire for the horizontal , would you
put:

One in the sky and one underneath it near ground

OR

Two in the sky. and a ground rod.

Bryan

-----Original Message-----
From: Alan Melia <Alan.Melia@btinternet.com>
To: LF-Group <rsgb_lf_group@blacksheep.org>
Date: 09 July 2003 14:20
Subject: LF: re Earth losses


>Hi Bryan and all, I agree with all that has been said so far about earth
>losses. One difficulty is that with amateur sized plots we all have
slightly
>different circumstances to overcome. To some extent we have to find out own
>particular "best solution"
>
>My own findings are that there is a limit with necessarily short
>counterpoise wires to the reduction in loss gained. ( A 100 foot "radial"
on
>136 is like putting out 4 foot radial wires on 80m and expecting an
>improvement!!). To some extent this depends on the local soil conductivity.
>It is no use doing measurements at 50Hz  or even DC as the result will be
>toally different at 136kHz. Plots on my web site show how the loss varies
>with the measurement frequency. I have suggested a simple bridge for the
>measurement on my web site. I have found that a proper measurement is the
>best way to avoid unnecessary hard work.....I am a comfirmed lazy B(oy). I
>find it best (and easiest) to measure the wire alone (not resonated) ...you
>can quickly see the result of any change of configuration.
>
>However, when you find extra rods or counterpoise wires are not giving any
>further advantage (usually very quickly) there are other unexpected things
>you can do. The best was popularised by Laurie G3AQC....put more wire in
the
>air. This can be by paralleling extra top wires or just extending the ends
>to " cover new ground". This obviously increases the aerial capacity but
>with an "L" configuration it reduces the loss resistance considerably.  A
>dipole of the sort you describe will probably measre out at about 200 to
250
>pF. If you double the wires with a spacing of at least 2 feet you will see
>the capcaity rise to about 450 to 500 pF. This has two effects, most
>obviuosly it reduces the size of the inductor required for loading
>(resonating), but secondly it will most probably half the ground loss. This
>is not effective unless the top wire is over relatively open ground. As
>Laurie has found extending a wire over lush Rhododendrons actually
increases
>the loss. My tests with Finbar suggested that doubling the capacity, halves
>the loss.
>
>Recent tests at Malin where Finbar has retuned his "umbrella" to 136 again,
>showed very poor aerial current levels initially. He achieved a
considerable
>increase in aerial current by running out an insulated "counterpoise" wire
>under the top load (5) wires. The aerial configuration is described in my
>web site. Note also that he is almost on the sea shore.
>
>Cheers de Alan G3NYK
>alan.melia@btinternet.com
>http://www.alan.melia.btinternet.co.uk
>
>
>
>