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Message-ID: <005001ca638b$c6dce610$0900a8c0@lark>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <4AFB477C.5090604@sighthound.demon.co.uk> <001501ca6326$ff28c710$0617aac0@jimdesk> <00f301ca6329$8ba907c0$0900a8c0@lark> <001901ca632a$d3356ab0$0617aac0@jimdesk> <011201ca6332$23e930c0$0900a8c0@lark> <000301ca637d$20bd9e40$0617aac0@jimdesk>
Date: Thu, 12 Nov 2009 11:26:19 -0000
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Subject: LF: Re: RE: Re: RE: Re: RE: G7NKS multiple WSPR decodes!
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Hi Jim,
Radio is not easy, we all learn as we go along, and are still learning. The
catch is that circuit diagrams are not anything more than descriptions of a
way of achieving the wanted function. They do not really show what actually
is there in terms of strays, parasitic components and unexpected couplings
via common impedances....you get a feel for this by experience and that is
what often gives it the a nature like a "black art". It makes the succeses
that more rewarding too. Stick at it and dont hesitate to
ask........sometimes formulating and asking a question will help you
understand the problem better, even solve it youself without further help.

Alan G3NYK

----- Original Message -----
From: "James Cowburn" <james.cowburn@virgin.net>
To: <rsgb_lf_group@blacksheep.org>
Sent: Thursday, November 12, 2009 9:47 AM
Subject: LF: RE: Re: RE: Re: RE: G7NKS multiple WSPR decodes!


> Hi Alan
>
> Thanks for the pointers here.  Very useful.   As it transpires, the laptop
> psu is now interfering on Rx so a loop has opened up somewhere.   I'm
going
> to dismantle the whole set up and re-wire/reroute from scratch....god help
> me!!
>
> I should have taken up stamp collecting as a hobby!
>
>
>
> 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 Alan Melia
> Sent: 12 November 2009 00:25
> To: rsgb_lf_group@blacksheep.org
> Subject: LF: Re: RE: Re: RE: G7NKS multiple WSPR decodes!
>
> Ah the dreaded laptop. Ok the isolation that is agood idea in that case
you
> must make sure you have some Rf grounds somewhere. Laptops seem to float
> there is not reason (for the digital engineers who designed them anyway)
to
> put an earth on the metalwork. The RF circuitating in those leads might be
> inducing hum. It might be worth trying an earth on any suitable but of the
> laptop metalwork....socket pillars ?? It definitely sounds as though it is
> hum getting into the PC sound system.
>
> Good Luck with it.
> Alan G3NYK
>
> ----- Original Message -----
> From: "James Cowburn" <james.cowburn@virgin.net>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Wednesday, November 11, 2009 11:58 PM
> Subject: LF: RE: Re: RE: G7NKS multiple WSPR decodes!
>
>
> > The soundcard leads are via an opto-isolator interface and the leads
from
> > the interface to laptop are wound on ferrite cores, approx 8 turns each
> for
> > tx and rx.
> >
> > I will check the mains psu for the dell d610 laptop as that could be
> > introducing hum or picking up rf from the tx (IC-735).  It might need
> > ferrites on the leads to and from the SMPSU
> >
> > I've just turned "the wick" down on the tx/rx inputs and also the rf
gain
> on
> > ic 735 till the needle just shifted in case it was being over-driven so
> I'll
> > see how that works.
> >
> > Not a prob when I was QRPpp but as sigs improve with dark nights I'd
> noticed
> > it too
> >
> > Thanks to John and others for heads up and suggestions
> >
> > With best regards
> >
> >
> > Jim
> >
> >
> > Dr. James Cowburn G7NKS
> > -----Original Message-----
> > From: owner-rsgb_lf_group@blacksheep.org
> > [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Alan Melia
> > Sent: 11 November 2009 23:49
> > To: rsgb_lf_group@blacksheep.org
> > Subject: LF: Re: RE: G7NKS multiple WSPR decodes!
> >
> > Hi Jim what kind of PC are you using. If a desktop are to sure it has
the
> > mains safety earth connected.....I have come across this problem before
> some
> > 3 connecter IEC moulded leads with only two wires in them!! If a laptop
> then
> > unless you use a radio earth that may all be floating. Sometimes it is
> > necessary to use an tranformer on the audio leads to and from the PC to
> gain
> > isolation from the hum and noise. I use old telephone hybrid
transformers
> > 600ohm to 600 ohm ferrite cored.
> >
> > Best Wishes
> > Alan G3NYK
> >
> > ----- Original Message -----
> > From: "James Cowburn" <james.cowburn@virgin.net>
> > To: <rsgb_lf_group@blacksheep.org>
> > Sent: Wednesday, November 11, 2009 11:30 PM
> > Subject: LF: RE: G7NKS multiple WSPR decodes!
> >
> >
> > > Hi John
> > >
> > > I'll have a look see.  I've noticed on strong sigs from me (few and
far
> > > between!) I get multiple decodes +50 and -50.   I'm not aware of any
> > obvious
> > > mains hum if I monitor my outgoing sigs and all leads are wound on
> ferrite
> > > cores, but clearly something is amiss.
> > >
> > > I shall look into it and see what I can find
> > >
> > > Cheers for the heads up
> > >
> > > 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 John P-G
> > > Sent: 11 November 2009 23:24
> > > To: rsgb_lf_group@blacksheep.org
> > > Subject: LF: G7NKS multiple WSPR decodes!
> > >
> > > Jim. LF
> > >
> > > It looks like G7NKS has a 50/100Hz problem on the audio - both in TX
and
> > > RX directions - there are up to 3 decodes by Jim of a single station
(eg
> > > G3YXM), spaced by 50 & 100Hz and I see also that M0BMU is also
reporting
> > > multiple decodes of G7NKS with the same 50/100Hz spacing.
> > >
> > > Jim, have you some mains hum affecting the audio in/out of the PC?
> > >
> > > Cheers,
> > >
> > > John
> > > GM4SLV
> > >
> > >
> > >
> >
> >
> >
>
>
>