[Elecraft] K3: Optimizing TEXT DECode for CW

[KM5Q]

The K3 TEXT DEC system works well on CW signals that are above the  
noise level, but to use it for weaker signals and noisy conditions  
requires some understanding and technique. Here's what I learned.

The decoder gets its signal from the same trigger as the CWT indicator  
bar. See for yourself -- When your display is in CWT mode, play with  
the RF gain so the CWT bar goes on and off. The moment it disappears,  
the decoding stops. As soon as the CWT bar flickers with noise, the  
decoder TRIES  to read the on/off signal. If the CWT bar is responding  
to clean code, you will get good text. If it isn't code,  
unfortunately, the decoder tries anyway, and produces junk text.

If the CW signal is audible but is not stronger than the noise, the  
CWT bar will flicker from the noise AND the CW, and the decoder will  
show too much junk. Once you accept that, you can reduce frustration.

To minimize junk text from QRN, hold TEXT DEC, then adjust threshold  
(thr ...) upward until it "squelches" the CWT bar. Now, The text  
decode will work if there is CW signal above the noise.

But now, set the threshold a little lower, slightly too sensitive.  
This will allow for varying conditions. When noise works the CWT bar,  
reduce the RF GAIN until the bar disappears. This is how to fine-tune  
the threshold quickly.

If you get static crashes or other erratic noise triggering the  
decode, don't let  "IISKSK IEN SKSK" distract you.  Watch the CWT bar.  
Let THAT tell you when to watch the text -- when it LOOKS like code  
rather than noise.

Maybe future firmware will improve the decoder so it will ignore  
noise, but for now, this is the best way I have found to use it.

Windy KM5Q
Santa Fe, NM
K3 #764