[CQ-Contest] Cross Band Split for the Elecraft K3

David Gilbert xdavid at cis-broadband.com
Mon Aug 16 01:23:10 PDT 2010

I posted this almost a year ago on the Elecraft reflector, but since the 
K3 is becoming more popular in contesting circles I thought maybe some 
folks here might find it useful as well.

By itself, the K3 does not allow cross band split operation.   It is not 
possible for the user to enable SPLIT with VFO A on one band and VFO B 
on another band, even with the subreceiver installed and CONFIG:  VFO 
IND set to YES.  This would have been a nice capability for running on 
one band while doing S&P for multipliers on another band via the dual 
VFO windows in N1MM.  In theory, N1MM can automatically put the K3 into 
SPLIT mode when you send something from the VFO B window, but the K3 
only allows that if the VFOs are on the same band.  It is possible, of 
course, to manually activate the A/B button, but that requires moving 
your hand from the keyboard to the K3 to push the button and it also 
causes N1MM to lose track of which VFO was making the contact (if that 
happened to be important).

Elecraft has had various requests for a firmware modification to allow 
cross band split, but they have stated that it would require a lot of 
relay switching of the low pass filters, among other difficulties, and 
that such a modification was not likely to occur in the foreseeable 
future.  I completely understand that, so I decided to see if I could 
accomplish essentially the same thing using N1MM rig control macros.  
Here is what I came up with:

{CATA2ASC SWT11;} ~~~~ action {END} {CATA2ASC SWT11;}


"{" and "}" are the N1MM command procedure brackets

"CATA2" designates VFO B

"ASC" designates an ASCII command syntax

"SWT11;" is the K3 macro for the A/B button

"~~~~" are four tildas in a row for a delay to let the K3 bandswitch
relays settle (less than four did not seem to give reliable results)

"action"    is the string you want N1MM to send or the action you want
N1MM to perform (send your callsign, the other station's callsign, your
report, etc)

"{END}" tells N1MM that "action" is finished and that whatever follows
is another command procedure

CATA2ASC is only executable if the window for VFO B in N1MM is active.
If instead the VFO A window in N1MM is active, N1MM will ignore the
command to flip VFOs and it will only execute "action".  In other words,
let's say that I have entered N6KR in the callsign entry field of Window
A while running on VFO A, and I have entered WA6HHQ in the callsign
entry field of Window B after finding him via S&P on VFO B.  If Window A
is active, the following N1MM macro will transmit "N6KR" from VFO A,
albeit with the delay caused by the four tildas:

{CATA2ASC SWT11;} ~~~~ ! {END} {CATA2ASC SWT11;}

On the other hand, if I make Window B active (such as by clicking on
Window B, hitting the "\" key, or by clicking on the Window B bandmap,
etc), that same N1MM macro will switch the K3 VFOs, wait for the relays
to settle, transmit "WA6HHQ" on what had been VFO B's frequency, and
then switch the VFO's back the way they were.

Since this macro actually performs an A/B exchange rather than a true
split, I think that the correct LPF always gets activated so that there
shouldn't be the usual concern about which bands can work together.

I'm not sure I'd want to yank the K3 back and forth a lot like this in
general (Elecraft  was definitely right about the relays), but for mult chasing
on one band while running on another I think it might be practical.

Dave   AB7E

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