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Re: LF: 136.96kHz testing

from [Roger Lapthorn] [Permanent Link][Original]
To: [email protected]
Subject: Re: LF: 136.96kHz testing
From: Roger Lapthorn <[email protected]>
Date: Sun, 18 Jul 2010 22:18:45 +0100
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Alan,

Yes, that ties up with the signal being stronger with the E-field probe held above my head. Agreed, that lambda/2pi is around 350m, so I'm only just exiting the near field region. Tomorrow I may do some QRSS3 tests locally to see if I can see the QRPp 136kHz signal a few kms away with E-field probe and FT817.

When I get properly started on the band - with a "real" (up in the air) antenna and some more power - I'd appreciate some reports from you Alan. You are indeed at a useful distance from me.

It may take me some time to get things together but 136kHz is a project that is slowly gathering some momentum here now. With HF being nothing to get excited about at the moment, I think 136kHz will be worth a try.

73s
Roger G3XBM



On 18 July 2010 21:52, Alan Melia <[email protected]> wrote:
Hi Roger dont forget the e-field probe has a sensitivity which is related to
its height not the length of the whip. If you are holding a conducting case
the effective height is say 2m , at carrying heigh say 1m the signal
collected will only be half as strong. You are barely out of the near field
at 400m but getting close.

Unfortunately I dont have a an LF receiver and aerial connected up at the
moment, I will have to sort that out because at 50 miles (ish) I would be an
interesting distance for you..

Alan G3NYK

----- Original Message -----
From: "Roger Lapthorn" <[email protected]>
To: <[email protected]>
Sent: Sunday, July 18, 2010 8:50 PM
Subject: Re: LF: 136.96kHz testing


> The measured power out from the PA is actually 250mW going into the earth
> electrodes. As a test I connected a PA0RDT designed active
> antenna<http://carc.org.uk//carc_ftp/G3GRO-PA0RDT-Active_Ant.pdf>run
> from a 9V PP3 battery and connected this to the (deaf at 136kHz) FT817
> and went for my walk across the fields. The signal was copyable (not
strong)
> at 0.4km with 10wpm CW. Signal was stronger if I held the E-field probe
> above my head.
>
> Those of you like Mal who work multiple continents on the band will thing
> this is nothing, but it gives me a starting point from which to
> progressively improve my system. I'm just amazed that 250mW into earth
> electrodes 20m apart can be heard Q5 at 0.4km with a 19 inch whip
handheld.
>
> More fun next week...
>
> 73s
> Roger G3XBM
>
> On 18 July 2010 17:14, Roger Lapthorn <[email protected]> wrote:
>
> > *This is the very beginning of my journey onto 136kHz....
> >
> > *For anyone very *very* close to Burwell, Cambs, JO02DG, I'm putting a
QRP
> > 10wpm keyer-generated CW message (later to be changed to QRSS3) out on
> > 136.96kHz CW into my earth electrode antenna. Power from the TX is about
> > 500mW, so ERP is just a few microwatts at most.
> >
> > I'd appreciate reports, but be amazed to get any until I start to run
some
> > more power into a real antenna.
> >
> > 73s
> > Roger G3XBM
> >
> >
> > --
> > http://g3xbm-qrp.blogspot.com/
> > http://www.g3xbm.co.uk
> > http://www.youtube.com/user/g3xbm
> > G3XBM    GQRP 1678      ISWL G11088
> >
>
>
>
> --
> http://g3xbm-qrp.blogspot.com/
> http://www.g3xbm.co.uk
> http://www.youtube.com/user/g3xbm
> G3XBM    GQRP 1678      ISWL G11088
>





--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM    GQRP 1678      ISWL G11088
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