From: "Gary - G4WGT" <g4wgt@tiscali.co.uk>
To: <rsgb_lf_group@blacksheep.org>
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Date: Tue, 21 Jul 2009 14:47:29 +0100
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Subject: LF: RE: Re: 504khz harmonic.
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Hi Alan, LF,

>You wrote :-
>Do you get the same effect on a wire, or passive antenna?

The pattern has come on again today at 1312utc & I have received it on my
resonant 500 kHz vertical Tx antenna using my 500kHz transverter with a
TS-440 & the pattern is present as described previously.

I think this concludes that it is not the Mini-Whip antenna or receiver.

So what can it be caused by?
Is it a product of something they are carrying out at the transmitter?

At the widest point (ie. the fan shape) the bandwidth is about 2kHz.

Food for thought!!!!

Cheers,

Gary - G4WGT.


-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Alan Melia
Sent: 20 July 2009 11:41
To: rsgb_lf_group@blacksheep.org
Subject: LF: Re: 504khz harmonic.

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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