Perhaps the problem is due to noise on the computer ground. The PX3 has
differential amplifiers at the I/Q inputs. For the computer-based
panadapter, it might help to connect the grounds of the computer audio
input connectors to the KX3 ground with a short, large-diameter wire.
Another possible solution would be to use audio isolation transformers
on the I and Q signals to isolate the grounds. That will cause a notch
in the panadapter response. The notch width will be twice the
transformers' low-frequency cutoff frequency.
Alan N1AL
On 12/20/2014 11:13 AM, Chris Tate - N6WM wrote:
Greetings and happy holidays Elecraft enthusiasts.
I have been putting together a portable contest/dx station using a KX3/KXPA100
combo. What a wonderful little setup. As part of my testing process, I have
setup a laptop computer for rig control. This works great in alot of respects,
Cat control.. no problem. Keying cw from the computer.. no problem. I have
run into a tiny issue, regarding the IQ out and how it integrates with computer
based spectral display applications and I am hoping the fine brain trust of
audio experts can help me out.
I have a creative EM 0204, and I have split out the IQ stereo into 2 channels
using a 1/8 stereo to mono a/b splitter, and subsequently feed IQ to the EM
0204 into the L/R mono ports. I am having some issues that I have not run
into.. for instance when I used to do this using an N8LP pan with my K3. (I
have done sufficient testing with other computers, sound cards to be aware this
is not limited to just this equipment). here is what my observations are:
CW Skimmer. Seems to work.. but the IQ balance seems to fall out of sync after
being dialed in. in other words from time to time multiple traces of signals
appear. this after adjusting with a fixed carrier on WWV to remove the traces.
Its almost as if there is an IQ instability of some kind and I was curious
what others have found.
PAN displays, NAP3, etc.: there seems to be a rather large artifact that
tracks with the center frequency making use of the pan display rather
impractical...maybe 20-30 Kc's or more. I assume this issue is resolved to
make the PX3 display an accurate spectral representation, and so am wondering
if there must be a setting or something I have adjusted incorrectly.
I also ran into an audio artifact where I could hear computer rfi through the
headphones with the IQ cable plugged in.. I was able to mitigate this using a
ground loop isolation cable.. keeping in mind I want to keep this setup
portable and useable in remote locations.
IF anyone who may have resolved some of these IQ out issues could chime in and
assist it would be greatly appreciated. I am trying to make this setup as
capable and portable as possible.
thanks in advance and look forward to your responses.
Chris
N6WM
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@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 n...@sonic.net
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft@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 arch...@mail-archive.com