[Elecraft] Possible phase noise question...

[David Cole]

Joe,

Thank you so very much, yes he did change computers...  :)  Also, the
additional information will help in solving this...  I'll pass all of
this on to him!

Joe, you are a bottomless pit of handy things to know, thank you again!

-- 
Thanks and 73's,
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On Mon, 2014-06-30 at 19:04 -0400, Joe Subich, W4TV wrote:
>  > Has anyone heard of this happening with a SignalLink sound card
>  > before?
> 
> Yes.  Did your friend change computers, connect Signalink to a
> different port, add (or remove) an externally powered hub?
> 
> Signalink has documented design issues - it lacks the V/2 regulator
> for the codec as recommended by the chip vendor, has a severe lack
> of bypasses on the 5V bus, insufficient filtering on the USB power
> (which becomes the 5V bus) and no regulation.  If the computer's USB
> power becomes noisy/unstable, that noise is imposed directly on the
> audio output of the codec *and* is further modulated on the audio
> via bias to the op-amp audio stages.
> 
> See documentation of the defects (and modifications to fix some of
> the shortcomings - including schematics) here:
> http://www.frenning.dk/OZ1PIF_HOMEPAGE/SignaLinkUSB-mods.html
> 
> If one wants a higher performance interface at a lower cost that
> will do everything that a Signalink will do and is willing to melt
> a little solder see: http://www.g4ilo.com/usblink.html
> 
> 73,
> 
>     ... Joe, W4TV
> 
> 
> On 2014-06-30 3:45 PM, David Cole wrote:
> > Hi,
> > I have a friend who lives about 1/2 to 3/4 of a mile from me.  He is
> > running a 706 MK2G, at around 10 watts.
> >
> > In the past, while using a Pro III, when he came on, I was able to copy
> > and see signals using JT65, and work stations right next to him.
> >
> > After getting the K3, I believe I was able to do this as well, or
> > better...  Suddenly his signal is sprayed across the entire audio
> > spectrum to the point, I can't even tell what frequency he is on...
> >
> > I get a solid white block using WSJTx.  He and I enlisted a third
> > friend, to insure it was not just me that is seeing him as very wide.
> > The third friend lives about 4 to 5 miles from both of us, and is line
> > of site to my friend with teh 706 MK2G.  When the 706  MK2G lets loose,
> > I see the spray, but my friend does not...  He sees a nice tight signal.
> > It looks and sounds like phase noise...  However...
> >
> > If he just does a Key down for CW at 50 watts, I can copy stations right
> > next to him...  It is as if his sound card, (Signal Link with internal
> > sound card), is adding a low level hiss to the audio, I see it due to
> > proximity, and my friend does not again, because he is much further
> > away...
> >
> > This has started suddenly, and the owner of the 706 can not pin a change
> > to it...  We swapped in a different 706MK2G, and the same problem still
> > happens...
> >
> > Has anyone heard of this happening with a SignalLink sound card before?
> >
> >