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" <[email protected]>
To: <[email protected]>
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: [email protected]
> [mailto:[email protected]] On Behalf Of Alan Melia
> Sent: 12 November 2009 00:25
> To: [email protected]
> 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" <[email protected]>
> To: <[email protected]>
> 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: [email protected]
> > [mailto:[email protected]] On Behalf Of Alan Melia
> > Sent: 11 November 2009 23:49
> > To: [email protected]
> > 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" <[email protected]>
> > To: <[email protected]>
> > 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: [email protected]
> > > [mailto:[email protected]] On Behalf Of John P-G
> > > Sent: 11 November 2009 23:24
> > > To: [email protected]
> > > 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
> > >
> > >
> > >
> >
> >
> >
>
>
>
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