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From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <000001ca0922$9cf3c580$6401a8c0@asus>
Date: Mon, 20 Jul 2009 11:40:49 +0100
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Subject: LF: Re: 504khz harmonic.
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Hi Gary, the mini-whip is not bad but where you are located it could be the
size of the 252 signal is producing some intermod/harmonics. Do you get the
same effect on a wire, or passive antenna?

I havent tried this but it may be possible to inprove the IMD performance by
paralleling a pair of J310s in the miniwhip, at the expense of increased
current drain.

Alan G3NYK

----- Original Message -----
From: "Gary - G4WGT" <g4wgt@tiscali.co.uk>
To: "LF -RSGB LF Group" <rsgb_lf_group@blacksheep.org>
Sent: Monday, July 20, 2009 11:12 AM
Subject: LF: 504khz harmonic.


> Hi All,
>
>
>
> Occasionally recently I have been seeing strange patterns around the
> harmonic line received on my SpecLab grabbers on 504kHz from the broadcast
> station at 252kHz.
>
>
>
> The patterns are not just seen using the Softrock SDR Rx but also with my
> JRC NRD-345, the only common device is the Mini-Whip active antenna.
>
>
>
> I seem to remember some while ago comments on this LF Forum regarding that
> station carrying out some experiments or tests involving digital data or
> something similar.
>
>
>
> I wonder if this is an effect of those tests as there were concerns that
it
> may cause interference on the 500kHz amateur band.
>
>
>
> Capture attached.
>
>
>
> 73,
>
>
>
> Gary - G4WGT - IO83QO.
>
>
>
>
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