Message-ID: <007401c9d2fa$863a6280$0301a8c0@mal769a60aa920>
From: "mal hamilton" <g3kevmal@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
References: <4A01AEA0.1030308@btconnect.com>, <003801c9cfed$3754c170$0301a8c0@mal769a60aa920> <4A094F88.31094.2E46CD4@mike.dennison.ntlworld.com>
Date: Tue, 12 May 2009 13:09:37 +0100
MIME-Version: 1.0
Subject: Re: LF: Re: Re: 500kHz Portable
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You are certainly NO EXPERT at amateur radio never mind LF/MF and especially 
antennas.
I have worked the world on LF/MF using Inv L antennas with the far end just 
above ground , and in normal CW mode.
Some time ago it was Comics, elevated lemonade bottles as coil  formers, 
thought an AR88D was a  diversity fly catcher.
What is coming next? The diversity UMBRELLA!!!!
My current MF antenna is a full 1/4 wave inv L, 100 ft high and performs 
well but for some this might be difficult, therefore use what you can get on 
your property and let the far end tilt down if necessary.
G3KEV

----- Original Message ----- 
From: "Mike Dennison" <mike.dennison@ntlworld.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Tuesday, May 12, 2009 10:29 AM
Subject: Re: LF: Re: Re: 500kHz Portable


>> You do not need 2 masts for an inv L or T antenna.
>> The so called horizontal wire(s) can slope down and the far end tied
>> to a bush or tree, or a stake in the ground via an insulator, as far
>> away as possible from the vert section, the longer the better. Keep it
>> simple. mal/g3kev
>
> This is quite wrong. Any slope downwards will reduce the effective
> height of a Marconi. Since ERP is a function of the square of the
> effective height this is extremely important. An umbrella is far
> preferable to an inverted-L in a single mast situation because a
> large amount of capacitance to ground can be achieved without much
> reduction of effective height.
>
> Based on my experience of LF portable (both on 73 and 136kHz), my
> advice is to make very sure that the remote ends of a Marconi are
> very well insulated as they carry large voltages. Keep well away from
> wet trees. This is not just a safety issue; any voltage leaked is
> power lost.
>
> Mike, G3XDV
> ==========
>
>


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