From: "James Cowburn" <james.cowburn@virgin.net>
To: <rsgb_lf_group@blacksheep.org>
References: <9afca2640909161002g67ff5386s580f457dd306ddad@mail.gmail.com> <PAEFLMFGBDKKCONLMLBIOEMMDEAA.ganymede444@btopenworld.com> <00a901ca370a$417ecc70$0217aac0@jimdesk> <261B000671B34914A1173F8F77A6D3CF@JimPC> <C2B4D69309994436A1C18F1A29179585@AGB>
Date: Wed, 16 Sep 2009 22:15:04 +0100
Message-ID: <00c901ca3712$c2d309f0$0217aac0@jimdesk>
MIME-Version: 1.0
Thread-Index: Aco3EKiIx2h814+ETNeT29A1TyRSmgAAZ2uw
In-Reply-To: <C2B4D69309994436A1C18F1A29179585@AGB>
Subject: RE: LF: Re: G7NKS multiple spots
Content-Type: text/plain;
	charset="us-ascii"
Content-Transfer-Encoding: 7bit
Sender: owner-rsgb_lf_group@blacksheep.org
Precedence: bulk
Reply-To: rsgb_lf_group@blacksheep.org


Ferrite, Ferrite and more Ferrite then!

Any suggestions as to where best to place clip on cores?  

Mains lead? 
Power lead from PSU (Icom PS55) to rig (IC735)?
All leads from ZLP interface to laptop? (Dell D610) (I currently have
ferrite clip ons on the microphone and speaker leads from ZLP to laptop)
Dell Laptop PSU?

All the above??

With best regards
 
 
Jim
 
 
Dr. James Cowburn

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Graham
Sent: 16 September 2009 21:59
To: rsgb_lf_group@blacksheep.org
Subject: Re: LF: Re: G7NKS multiple spots

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
>
>
>



>
> No virus found in this incoming message.
> Checked by AVG - www.avg.com
> Version: 8.5.409 / Virus Database: 270.13.101/2376 - Release Date: 
> 09/16/09 11:21:00
>