Bob,

 

Thanks for the scope shot and info. I compared the waveform to the QST K3S 
review, which seems to show a little over 10ms before RF appears. Is this 
because they used different settings?

 

Will be interesting to see how the new radio CW looks in time and frequency 
domains. Also how the turnaround latency is managed.

 

Tks,

73 Ed w2rf

 

 

 

From: Bob Wilson, N6TV <n...@arrl.net> 
Sent: Thursday, June 11, 2020 2:05 PM
To: Elecraft Reflector <Elecraft@mailman.qth.net>
Cc: E.H. Russell <e...@qrv.com>
Subject: Re: [Elecraft] CW rise time setting

 

On Mon, Jun 8, 2020 at 12:31 PM E.H. Russell <e...@qrv.com 
<mailto:e...@qrv.com> > wrote:

I suppose shaping of the curve corners removes harmonics introduced by the 
abrupt transitions, allowing an accelerated ramp inbetween. But does this 
really reduce the total rise time to 2.5ms? It seems that the softening process 
must take some time. Wish I had a K3 here to scope against other radios. 
Anything published out there?

 

Ed,

 

Per your request, I am publishing this scope screen capture which plots the CW 
rise time in my K3 with the KSYN3A synthesizer upgrade.  It's about 4 ms from 0 
RF to full RF (2 ms per horizontal division):

 

https://www.kkn.net/~n6tv/N6TV_K3_Ser_1494_FW_05.64_TX_DLY_8_CW_QRQ_OFF.png

 

The vertical markers are there to illustrate that CONFIG:TX DLY nor 008  
provides only about 6 ms of RF delay after "KEY OUT" goes to ground, not 8 ms, 
and there is jitter in that delay as well (not shown).  If CW QRQ mode is 
enabled, the delay drops to about 4.6 ms and the TX DLY setting is completely 
ignored.

 

This was discussed here two years ago.  See this post for suggestions on how to 
avoid hot-switching a non-Elecraft amplifier driven by a K3 or K3S:

 

http://elecraft.365791.n2.nabble.com/Default-K3-transmit-delay-may-be-too-short-for-slow-QRO-amplifiers-td7641779.html
  

 

73,

Bob, N6TV

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