[Elecraft] KX3 + SignaLink USB noise problems

Tue Jun 23 21:36:32 EDT 2015

Having performed further science, here’s what I’ve got:

1. When the Signalink is connected to my laptop but not the KX3, nothing special.
2. When the Signalink is connected to my KX3 (mic jack so I could monitor the receive audio), broadband noise.
2a. in this instance, noise is quieted by placing my hand on or near the Signalink.
3. When the Signalink is connected to my laptop but not the KX3 *and* the KX3USB is connected to my KX3, broadband noise.
3a. in this instance, noise is louder when I put my hand on or near the Signalink.
4. When the Signalink is connected to my laptop and the KX3 and the KX3USB cable is connected to my KX3, a very small amount of (equally broadband) noise.

This seems distinctly ungood if a little messing with capacitance causes that.

All of these seem to be radiated either by the Signalink itself or by a cable connected to it - ‘course, that could include the USB cables and the laptop as well. Whenever I turned the null on my antenna towards their general direction, the noise got quieter (but was still strong enough to be bothersome).

Gonna try those mods as soon as my order from Mouser gets here. Crossing my fingers it’s by Field Day.

73
Amy
K3ISI

> On Jun 23, 2015, at 5:45 PM, Amy Wilhelm <netcrusher88 at gmail.com> wrote:
> 
> Yeah, fldigi doesn't seem to know what to do with I/Q. Yet. 
> 
> CAT control isn't strictly necessary. But it's nice to have with fldigi, WSJT, and various logging software. 
> 
> 73
> Amy
> K3ISI (granted today)
> 
> Sent from infinite squirrels at infinite keyboards
> 
>> On Jun 23, 2015, at 5:18 PM, k3ndm at comcast.net wrote:
>> 
>> Guys, 
>> Two things. First, you can't use the I&Q data on the KX3 to transmit and I'm not really sure you can use it with FLDIGI; I believe FLDIGI only expects audio. And second, I'm not sure why you need to use ACC1. The only connections you should need to use is to the KX3 mic and the USB connector for the SignaLink. The SignaLink will key the radio with out needing other connections. This may help some of the noise problem. 
>> 
>> 73, 
>> Barry 
>> K3NDM 
>> 
>> ----- Original Message -----
>> 
>> From: "bs usb" <bsusb at k5dkz.com> 
>> To: "elecraft" <elecraft at mailman.qth.net> 
>> Sent: Tuesday, June 23, 2015 5:01:45 PM 
>> Subject: Re: [Elecraft] KX3 + SignaLink USB noise problems 
>> 
>> 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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>> 
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