Message-ID: <C2B4D69309994436A1C18F1A29179585@AGB>
From: "Graham" <g8fzk@g8fzk.fsnet.co.uk>
To: <rsgb_lf_group@blacksheep.org>
References: <9afca2640909161002g67ff5386s580f457dd306ddad@mail.gmail.com> <PAEFLMFGBDKKCONLMLBIOEMMDEAA.ganymede444@btopenworld.com> <00a901ca370a$417ecc70$0217aac0@jimdesk> <261B000671B34914A1173F8F77A6D3CF@JimPC>
In-Reply-To: <261B000671B34914A1173F8F77A6D3CF@JimPC>
Date: Wed, 16 Sep 2009 21:58:55 +0100
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Subject: Re: LF: Re: G7NKS multiple spots
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JIm,

I think you  find that is  caused by 50 hz mains hum .... may be a hum loop 
in the  audio system / pc-tx earthling , not likely to  be psu problem as 
frequency is 50 (fund)  and 150 ( 3 rd harm)

I had a similar problem with my  valve HF set , that was a slight  ripple on 
the PA  HT line caused by the  100% duty cycle of wspr, not part of the 
design criteria for  ssb/cw , caused  spots to appear +/-  100  Hz due to 
the  full wave  rectification in the  psu

G .

--------------------------------------------------
From: "James Moritz" <james.moritz@btopenworld.com>
Sent: Wednesday, September 16, 2009 9:40 PM
To: <rsgb_lf_group@blacksheep.org>
Subject: LF: Re: G7NKS multiple spots

>
> Dear Jim, LF Group,
>
>
>> Me too.  I am getting 3 traces (!) from Jim M (he is 9+10 and audible!)
>> and
>> a biggish one from Gus too
>
> I am seeing low-level (about -25dB) sidebands on your signal  at +/-50Hz 
> and
> +/-150Hz, which are giving rise to the extra spots.  I think something
> similar is happening when you receive my signal. I am not getting similar
> multiple spots from other nearby stations, nor am I seeing the same
> sidebands on other strong signals, so I think they must originate in your
> station somewhere - possibly audio being affected by mains noise, or some
> sort of residual FM of an oscillator in your rig?
>
> Cheers, Jim Moritz
> 73 de M0BMU
>
>
>



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