[Elecraft] K2 PC CW keying

[Jim Brown]

One of WriteLog's major weaknesses is the extreme disorganization of
its documentation. The NPN inverter I described to you is SOMEWHERE in
the doc, either on the K8JY website or buried in a help screen
somewhere, but they don't call it an inverter, they call it a level
shifter. I figured out what was going on when I tried to make WriteLog
key my TenTec Omni V, then started asking questions and scouring the
meagre documentation for answers. Eventually I found the NPN circuit
and built it. 

The difference in logic (i.e., negative or positive) may depend on
whether you use the parallel port or serial port in WriteLog to key the
radio.  I use the serial port. WriteLog uses the DTR line of the serial
port (pin 4 of the 9-pin at the computer end) as the key line. In the
K2 serial cable, I connect pin 4 at the computer end, but don't connect
it to the DB9 at the K2 end. Instead, I pull it outside the connector
to drive the NPN. 

If you're going to use the PTT to voice key the radio, you'll need to
make a new cable to bring pin 7 (RTS) over to the radio. If you do
this, I suggest you use CAT5 between the computer and the radio. I'm in
the process of building one now -- gotta run to RS for another DB9
connector. But what I really should do is find one of the much nicer
DB9's that Wayne and Eric found to include in the kits. 

Yes, the diodes DO need to go right at the input to the K2. The reason
is that the K2 includes logic within the keyer to interpret a parallel
input to both dot and dash as a keyer or hand key. The diodes would
only work for a keyer that had that logic.  I don't know if any other
radios do. 

Jim K9YC

On Wed, 24 Dec 2003 10:40:44 -0500, n4gi@tampabay.rr.com wrote:

>Ahhh.... An informative response, finally.
>
>I think that the #4 part is what I'm missing, I'd have never known unless someone told me.  Is this documented somewhere?  I use Writelog also, I'm curious why I need to invert the logic output for the K2 but not my 1000MP.  It's never been a problem before.  This mod may be tricky, since I use a DXDoubler 2 radio control box up ahead of everything.  It does the keying, PTT, A/B rig switching.  I guess I'll need to somehow put the diodes right at the keying input to the K2 so I don't screw things up with my MP. 
>
>73,
>Blake N4GI