[Elecraft] K2 CW speed

[Bill Coleman]

On Feb 22, 2005, at 11:43 AM, Andrew Moore wrote:

> Has anyone been successful in pushing the K2 beyond the 70 WPM external
> keying limit for CW operation?

At 60 wpm, each element is 20 ms long. Given a 5 ms rise and fall time 
(assuming you've made the key-click mod), that's only 10ms of 
full-power signal. Going much faster than this may be impractical. 
Certainly the initial element is going to get clipped severely, and the 
K2 does not support CW PTT to prevent this. (This is probably a good 
request for the next revision of firmware -- but it would mean the 
internal keyer would be disabled)

100 wpm, elements are only 12 ms long - barely 2 ms at full output. At 
that speed, I'd begin to wonder about the group delay response of the 
remote receiver's filters....

>  Does it adhere to spec (70 WPM) or
> differ in practice?  Anyone try any hardware or firmware mods to bump 
> up
> the speed?  I'd love for this great high performance CW rig (or even 
> the
> K1 or KX1, despite the QRPish nature of them) to be able to handle up 
> to
> 100 WPM.

Here's my question - what person can copy 100 wpm? Only a handful of 
people in the world can copy 60 wpm!

If this is meant for machine copy, then perhaps it is time to look at 
the lesson learned by the early HF RTTY users in the 1950s. At the 
time, FSK wasn't legal. These guys were running RTTY using OOK. It 
worked, but copy was poor.

In theory, FSK has a 2 dB advantage over OOK in the presence of 
Gaussian noise. PSK has an additional 2 dB advantage over FSK.

The bottom line -- if you are looking to run a 100 wpm data link on HF, 
there are a lot more robust methods of modulation than OOK - CW. FSK is 
gobs better, and you can run it up to 300 baud (using CW keying between 
mark and space, this would be 360 wpm, as 60 wpm is 50 baud)


Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901