[Elecraft] KX3 + SignaLink USB noise problems

[bs usb]

With the I/Q output from the KX3 and fldigi software on the Mac why do 
you even fool with signal-link?

Amy Wilhelm wrote:
> Yes, it's another post about that little interface we all love to hate...
>
> I went through archives and didn't find anything that *quite* matched
> this, so I wanted to know if anyone's experienced it or has tips.
>
> Aside from the widely reported high noise floor (it *seems* to be
> possible to just crank the RX volume to get past that a little) I have
> a couple of symptoms that are...strange at best:
>
> 1. If I have the KX3 connected to my laptop via the KX3USB cable to
> ACC1, and then attach the Signalink to a different USB port, I
> immediately experience broadband noise. Changing the IF doesn't seem
> to help this, and I seem to be tuning past peaks of noise all across
> the band. If I detach the Signalink, most of these symptoms go away (I
> think some of the peaks are just out there).
>
> 2. The Signalink seems to be radiating a significant amount of QRM -
> or the cables connected to it (but not necessarily to the KX3) are.
> Because I use an Alexloop, my antenna is always right next to my
> laptop, interface, radio, all that fun noisy stuff. Conveniently
> magloops have this great null directly perpendicular, so I've worked
> out that turning my antenna perpendicular to the Signalink - not
> necessarily my laptop or radio - reduces the noise floor significantly
> (both wideband noise and weird little blips every 150 Hz or so). I'm
> not actually sure at the moment whether I've checked if unplugging my
> Signalink makes a big difference, but evidence would suggest I should
> try that.
>
> This is all with the KX3 operating off of a gel cell (so no QRM
> there), the Signalink with the official KX3 snap-in jumper board and
> cables, a Macbook Air running from its internal battery, an Alexloop,
> and the included KX3USB cable.
>
> Any help would be much appreciated - I've seen the page suggesting
> some mods to the Signalink and I'm more than willing to do those if
> those would help with the symptoms I've been seeing here, but wanted
> to check if anyone thought that was reasonable (and that my diagnosis
> is) first.
>
> 73
> Amy Wilhelm
> WN5FIZ
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