[Elecraft] CW keying circuit

[Mark Schreiner]

Carter W. Craigie wrote:
> Can someone send me, or point me to, a CW keying circuit for a COMM port that
> will work with the K2?
>   


Hi Carter,

I went with the simple Serial Port circuit shown at the following website:

taggart.glg.msu.edu/wb8dqt/cwpage.htm

Actually, I may have gotten it from some other website, but without 
opening the DB9 shell and inspecting, I'm pretty sure that was the 
equivalent circuit.  It was easily found by doing a Google search (like 
everything in life).  The circuit is built right inside of the DB9 
connector shell and can go to a mono plug directly into the back of the 
K2.  No external voltage is required.  I've used it connected directly 
to the back of a PC (desktop and laptop) as well as using it with a USB 
to Serial converter dongle.  I think the keying is not quite perfect, 
though.  I have used this with the KA3JWE PA QSO Party logging program 
as well as generally using it with the N1MM Contest Logging software.  I 
set the K2 for hand key operation (MENU:  InP:  HAnd), otherwise you get 
really interesting (bad) results. 

I actually use a stereo plug but only connect the tip and shield and do 
not connect the ring.  Also, to keep the Bencher paddles handy for when 
I want to send something manually rather than using the memories in the 
logging program (or K2 memories) or the keyboard (Alt-K for keyboard 
operation on the KA3JWE software, I think it is CTRL-K with N1MM), I 
have the paddles going into an old MFJ memory keyer which I can easily 
set the speed as needed and the output of that goes into a Y-adapter 
cable.  So, actually, I have the CW Serial interface cable and the 
output of the MFJ keyer going into the two Y-cable inputs and the single 
end going into the back of the K2 key input.  This works well for me. 

I mentioned that the Serial keying isn't perfect.  It has been mentioned 
that this has to do with timing issues, even on very fast compukers.  I 
didn't notice any extra degradation using the USB to Serial interface 
and figured it would be "less work" to use it on CW keying than for rig 
communication, which I don't remember if I've tried yet.  This is handy 
for use with laptop compukers that only have one serial port but 
generally have at least one USB port (or you can get more ports with 
additional PCMCIA card or a USB Hub). 

I think I will build a Parallel port CW keying interface as well, which 
can be found on the web by doing a Google search.  As I understand the 
timing is a bit better on the P-Port than the S-Port.  The only reason I 
haven't done so yet is that the KA3JWE software didn't support the 
P-Port for keying (as I recall), however I'm likely to not be using 
KA3JWE software next year and following.  I just checked and found that 
the N1MM Logger does support LPT 1 - 3, so I'll definitely throw a 
circuit together to try that as well before the next contest. 

Anyone have success using USB-Serial adapter cable (with the correct 
cable as built with the KIO2, I guess a pseudo-serial cable for lack of 
a better name) for communications between the K2 & computer for getting 
frequency and mode info?  This may have been a recent post thread, so 
please, I didn't mean to open a can of worms by asking this, just a 
simple question.  I am currently using the Belkin adapter (P/N P43293-B 
or F5U409-CU which is by the barcode on the original package).  
Actually, this reminds me of another issue altogether that I'm going to 
do in a separate post.

73,

Mark, NK8Q
K2 #4786