A trivial pan-adapter for use with the Elecraft KX3, using gnuradio (see "Notes" below) and hamlib, written in Python and released under the GPLv3. There are some screen-shots here: http://www.g0hww.net/2012/10/gnuradio-hamlib-and-kx3.html and more here: http://www.g0hww.net/2012/11/more-buttons-in-gr-kx3-more-bugs-too.html.
It uses pulseaudio for the soundcard I/Q input by default, so when gr-kx3 is running, run Pulse Audio Volume Control and choose the correct soundcard for the stereo I/Q input from the KX3. For me, the application appears on the Recording tab, as
ALSA plug-in [python-2.7]: ALSA Capture
The Frequency text input control will directly retune the radio when the frequency control mode drop down list is set to "Entry". In that mode, the rig's VFO is not polled. When the frequency control mode drop down list is set to "Track" the VFO frequency of the rig is polled. When set to "Track & Click", the rig VFO is tracked and clicking in the waterfall display will retune the rig to the selected frequency.
You can click in the waterfall (not in the spectrum plot) to re-tune the radio to that frequency. You can select Step size increment from the drop down list, and nudge the frequency up and down with the Step Up/Down buttons. Selecting the option "Dwell" for step-size automatically sets the step size to half the sampling rate, such that the spectrum is stepped through contiguously without gaps.
Regarding frequency offsets from PBT settings and IF offset configurations, all bets are off for now, until the support for the FI command is added to the KX3 (which has been promised by Wayne from Elecraft).
The code uses hamlib's rigctl (via pexpect) which then talks to rigctld over TCP/IP, so you need to have rigctld running with a serial connection to the radio, using a command like:
rigctld -m 229 -r /dev/ttyUSB0 -s 38400
Initially I found that I had to bodge hamlib itself in order to increase the timeouts for the KX3, which were exceeded whenever I switched bands on the radio. Newer versions of hamlib may make this unnecessary, and gr-kx3 is now more robust. There are some details of my original bodge here: http://www.g0hww.net/2012/11/a-better-bodge-for-hamlib-and-kx3.html
I tend to stay fairly up-to-date with my gnuradio versions, and gr-kx3 is typically updated to work with the latest versions of gnuradio. This may cause some incompatibilities with older gnuradio versions. YMMV, but hey, you can always hack the python yourself :)
Ubuntu Users can get probably get newish packages from the gqrx ppa, see here: https://launchpad.net/~gqrx/+archive/releases Otherwise, try following one of the methods listed here: http://gnuradio.org/redmine/projects/gnuradio/wiki/InstallingGR
Stefano, IZ0MJE has posted about projects using Funcube Dongles and USRPs to tap IF outputs from other Hamlib controlled transceivers, reusing code from gr-kx3. See here: http://www.tarapippo.net/gnuradio/ft950.html