[Elecraft] Possible phase noise question...

[Matt VK2RQ]

If fact, the circuitry for that very nice "homebrew" solution is for VOX. If you have a modern radio like the K2/KX3/K3, it most probably has a VOX circuit already built in, so the "melting solder" part reduces to simply putting the right connectors on the end of some cables.

73,
Matt VK2RQ

> On 1 Jul 2014, at 9:04 am, "Joe Subich, W4TV" <lists at subich.com> 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?
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to matt.vk2rq at gmail.com