Re: CW rise time setting
Posted by
Edward H Russell on
Jun 12, 2020; 10:23am
URL: http://elecraft.85.s1.nabble.com/CW-rise-time-setting-tp7661876p7662080.html
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 <
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Sent: Thursday, June 11, 2020 2:05 PM
To: Elecraft Reflector <
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Cc: E.H. Russell <
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Subject: Re: [Elecraft] CW rise time setting
On Mon, Jun 8, 2020 at 12:31 PM E.H. Russell <
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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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