[Elecraft] K2 Cross-mode operation

[John Webster]

Dear Elecrafters: [A long-ish treatise]

There has been some discussion of cross-mode operation on
the K2.  Some have wished for firmware changes to effect
something similar to what they enjoy on the KX1.  As others 
have pointed out, cross-mode CW/SSB contacts are possible 
on the K2 with some fiddling with RIT/XIT controls.  With
talk of restarting an Elecraft phone net, and with the upcoming 
EQP in mind, I set out to see exactly what gives. [You can 
skip to the end if you are only interested in the 'how to do 
it' part.]

I have discovered that cross-mode operation is much easier to 
accomplish on the K2 (as it is), than I at first thought would be 
the case.  I've tested the following using my TS850 as the other 
station while operating the K2 on a dummy load.  I believe 
what follows is correct, but please report any mistakes you 
may find.

First, let's get receiving CW while on SSB out of the way as it
is a 'no brainer'.  Simply copy the code if someone calls you on
CW and you are on SSB!  It is the other stations' responsibility
to be heard (i.e. get the offset right, if needed).  If the CW signal
is off frequency (i.e. you just hear clicks or AGC pumping, etc) 
just use your RIT to get good copy.  Receiving CW while in 
an SSB mode is not a problem.

The reverse is a little more complicated.  If you wish to work a
station on SSB while transmitting CW, we first need to clarify
three conventions, and then set the rig up accordingly:

1.  First (and easiest) is the convention used on the ham bands.
We use LSB below 10Mhz and USB above.  Thus 160, 80, 40 
use LSB, and 30*, 20, 17, 15, 12, 10 use USB). *In some parts 
of the world 30 meters is not a CW only band. [I'm ignoring 60 
meters because it is a maverick.  CW is expressly prohibited, it 
is USB only (running against the grain of ham convention), and 
thus cross-mode operations are not possible on this band.]

2. The design used in the K2 switches the sideband used on CW 
from 21 Mhz on up.  So you are listening to one side of the carrier 
on 160m thru 17m, and on the other side from 15m to10m. 

3.  This results in three groupings of three bands each, one group
using  LSB (160, 60, 40), and two groups using USB (30, 20, 17)
and (15, 12, 10).  Let's call them the 'LSB group', the 'mid-USB 
group' and the 'top-USB group'.

Here then is the set up:

To send CW you must be in CW mode on the K2.  Open the 
crystal filter up to its widest setting so you can read an SSB 
signal.  Use no audio filter, or set it to its widest setting.
(I have FL1 set to the SSB filter even on CW, and have the 
KDSP2 CW audio filter 1 set to LPASS, so this no problem).

[Note in what follows your K2 LED frequency display will 
read either below or above the reading you would have if
your rig was set to SSB, by the amount of your sidetone
offset.  If you are calling stations already on the air, this is
of no consequence.  If you need to call on a specific freq.
(e.g. net) in such a way that you will be able to copy any 
SSB response without shifting frequency, see below.]

1. For Group 1, LSB (160, 80, 40) Set your mode to
-CW normal-, and simply tune in the SSB signal for normal 
pitched voice and transmit!  The station on SSB will hear 
your CW at your sidetone pitch (in my case 600 Hz).  
This is not critical.  There is nothing more to it.

2. For Group 2, mid-USB (30, 20, 17) Set the mode to 
-CW reverse-, tune the station in and transmit. As above.

3. For Group 3, top-USB (15, 12, 10) Set the mode to
-CW normal-, tune the station in and transmit.  As above.

In some cases you might need to call for an SSB station
on a specified frequency.  If so, follow these procedures:

1. For Group 1, LSB (160, 80, 40)  Be in -CW normal- 
mode. Then tune the MAIN tuning dial to the required 
frequency (as if you were on SSB).  Then, and only then
(the sequence is important), turn on both your RIT and 
XIT, and set the offset to read - (minus) by the amount 
of your sidetone offset frequency.  The K2 has RIT/XIT 
markings that make it easy.  You do not have to be exact. 
(For my sidetone of 600 Hz the offset is just past the 
halfway mark between 0 and -1k marks).  When you 
transmit, SSB stations will hear your CW tones right on 
the frequency you set originally and you should find any 
voice reply sounds natural.  Note the LCD readout will
indicate the RIT/XIT offset frequency, once set.  If you
want to check your "SSB equivalent" frequency just set
RIT off momentarily.

[Note, there is a design limit to the frequency accuracy 
obtainable on a K2.  Worst case will be on the highest 
bands.  But you should always be close enough.  This 
also presumes that your Filter BFO frequencies have 
been set correctly.  If the voice does not sound right, 
tune it in with the MAIN tuning dial.  Do not change 
the RIT/XIT setting.]

2. For Group 2, mid-USB (30, 20, 17) As above, but 
you must be in -CW reverse- mode, and tune your RIT/
XIT to read up (plus, +) by the amount of your sidetone 
offset.

3. For Group 3, top-USB (15, 12, 10) As above, but 
you must be in -CW normal- mode (not CW reverse), 
and tune your RIT/XIT to read up (plus, +) by the 
amount of your sidetone offset.

Now after all that, here it is at its simplest (you can 
add this to your mini-manual or operating guide sheet): 

1. In CW mode, open up filters, tune SSB signal normally 
and transmit. [To transmit on a specified frequency, tune 
there, then turn both RIT/XIT on.  For LSB (160-40) set 
offset lower (- minus) by the amount of your sidetone 
frequency (e.g. 600Hz).  For USB (15-10) set offset 
higher (+ plus) by the amount of your sidetone frequency.

Except:

2. On the mid-USB bands (30, 20, 17) use -CW Reverse-
to decipher the signal, and transmit. [To transmit on a 
specified frequency, tune there, and then turn both RIT/
XIT on, and set the offset higher (+ plus) by the amount
of your sidetone frequency (e.g. +600Hz).]

Hope this helps.

73

John, N6JW
K2 #3290
K1 #754