Message-ID: <01d301c86fba$5d7f4080$0301a8c0@g3kev>
From: "mal" <g3kevmal@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
References: <021420082154.26694.47B4B8AF000ED3D10000684622155863949C9D01CD05@comcast.net> <000b01c86f6d$8dbf6bf0$0d00000a@AGB>
Date: Fri, 15 Feb 2008 09:58:11 -0000
MIME-Version: 1.0
Subject: Re: LF: Re: NOV UPDATE
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As a rough guide to get started, assume the average amateur antenna is 1%
efficient which is doubtful then you would need 100w fed to the antenna.
Since a more realistic efficiency figure might be 0.5% or less you would
need 200w. The average pa efficiency is about 50% therefore you would need
anything between 200 and 400watts dc input to get into the ball park and
generate 1w erp.
A large 1/4 wave inv L antenna might only be 5%  efficient if you are lucky
at this freq, because the vertical part would normally only be a few metres
high with a very long horizontal part.
The antenna environment then needs consideration, buildings, trees, hedges,
other antenna wires in the vicinity. Your 1w erp might effectively be
reduced to  micro watts.
Check the near and far fields.
I recently removed a long wire rx antenna running near my 500 khz antenna
and gained 2 db.
The above info is a rough guide because every radio amateur installation is
different, the antenna efficiency is hard to determine, hence the erp.
73 de Mal/G3KEV


----- Original Message -----
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: Friday, February 15, 2008 12:55 AM
Subject: Re: LF: Re: NOV UPDATE


> That's true , be interesting to  see what kind of power level you need to
> get 1 watt erp
> from such a large antenna array ,  looking at the  calculators carnt be
more
> than   50  watt's
> tops , suppose a lift from 5watts  to  50watts  might help  ?
>
> G ..
>
>
> ----- Original Message -----
> From: <k2ors@comcast.net>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Thursday, February 14, 2008 9:54 PM
> Subject: Re: LF: Re: NOV UPDATE
>
>
> > Graham,
> >
> >   UK to W has only been done a couple of times under the best of
> > conditions, the new power levels might facilitate more contacts,
> > particularly with U.K. stations who don't live near the coast.
> >
> >
> > --
> > 73 Warren K2ORS
> > WD2XGJ     136-140kHz
> > WD2XSH/23 505-510kHz
> > WE2XEB/2   160-189kHz
> > WE2XGR/1 505-515kHz
> >
> > FN42hi
> > http://www.w4dex.com/wd2xgj.htm
> >
> > -------------- Original message ----------------------
> > From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
> >> Must of missed something here !
> >>
> >> UK to  W  has been done on 100 mW , just takes skill not power !
> >>
> >> G ..
> >>
> >>
> >>
> >> ----- Original Message -----
> >> From: "mal" <g3kevmal@talktalk.net>
> >> To: "rsgb" <rsgb_lf_group@blacksheep.org>
> >> Sent: Thursday, February 14, 2008 3:22 PM
> >> Subject: LF: NOV UPDATE
> >>
> >>
> >> > New updated NOV arrived this morning, no excuse for weak signals
> >> > anymore
> >> > on
> >> > 500 khz
> >> > Mal/G3KEV
> >> >
> >> >
> >> >
> >> >
> >> > --
> >> > No virus found in this incoming message.
> >> > Checked by AVG Free Edition.
> >> > Version: 7.5.516 / Virus Database: 269.20.5/1278 - Release Date:
> >> > 2/14/2008
> >> > 10:28
> >> >
> >> >
> >>
> >>
> >>
> >
> >
> >
> >
> >
> > --
> > No virus found in this incoming message.
> > Checked by AVG Free Edition.
> > Version: 7.5.516 / Virus Database: 269.20.5/1278 - Release Date:
2/14/2008
> > 10:28
> >
> >
>
>
>
>
>
> --
> No virus found in this incoming message.
> Checked by AVG Free Edition.
> Version: 7.5.516 / Virus Database: 269.20.4/1277 - Release Date:
13/02/2008 20:00
>
>