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Re: CW rise time setting

Posted by Edward H Russell on Jun 08, 2020; 6:51pm
URL: http://elecraft.85.s1.nabble.com/CW-rise-time-setting-tp7661876p7661881.html

I'm used to CW rise times in th 4-7ms range. Is this 2.5ms arrived at by a
different metric? Is the curve added by sigmoidal shaping somehow excluded
from the measurement?

 

Ed / w2rf

 

 

 

-----Original Message-----
From: [hidden email] <[hidden email]> On
Behalf Of Richard Stutsman
Sent: Monday, June 8, 2020 1:31 PM
To: David Gilbert <[hidden email]>
Cc: Elecraft Reflector <[hidden email]>
Subject: Re: [Elecraft] CW rise time setting

 

Yes, I would regard a 2.5 msec rise time (using appropriate sigmoid

shaping) to probably be ideal, in which case I would have no desire to
modify or shorten it. I'll bet it will sound even better than a Drake or a
Ten-Tec!

 

I hereby withdraw my previous request/opinion.

 

Rick N6IET

 

On Mon, Jun 8, 2020 at 10:27 AM David Gilbert < <mailto:[hidden email]>
[hidden email]> wrote:

 

> You don't need to generate clicks to have a crisp CW tone.  Elecraft

> uses a pretty much optimally shaped waveform (some version of a cosine

> function) and if I remember correctly the rise time is only about 2.5

> msec, although I could be wrong about that last part.  And while you

> may be careful not to use short rise/fall times when the band is

> active, in the past there have been folks on the contesting reflector

> who openly admitted they purposely generate clicks by shortening the

> rise/fall times to give themselves elbow room.  I will always

> appreciate that Elecraft doesn't give those miscreants the means to
pollute the band.

>

> 73,

> Dave   AB7E

>

> On Mon, Jun 8, 2020 at 9:23 AM Richard Stutsman <
<mailto:[hidden email]> [hidden email]> wrote:

>

>> I for one would like to have some control over the rise/fall times.

>>

>> You want the cleanest (narrowest) of CW signals when operating on a

>> crowded band or in a contest - unless you're a rare DX station. Most

>> of my operations are 22wpm rag chews on very uncrowded bands. We're

>> often the only discernible signals on an entire CW band. And

>> conditions are often noisy with deep QSB. Why not allow those of us

>> operating in those circumstances to shorten the rise times a bit,

>> which makes it easier to copy in noisy conditions, when any close-in

>> clicks or thumps aren't going to bother anybody? Copying a 'soft'

>> weak CW signal is like trying to read a 'crisp' signal that's an

>> entire S-unit weaker, IMO.

>>

>> My TS-590sg let's me do that, and I love it!

>>

>> Will the K4 sound as good as a Drake T4C? (Just askin'.)

>>

>> Rick N6IET

>>

>> > N4ZR wrote:

>> > >

>> > > Will the K4 have options for setting CW rise and fall times...?

>> > Hi Pete,

>> > Probably not. We've always been very careful to ensure our rigs

>> > have an exceptional clean, click-free CW signal. (Third-party

>> > testing bears this

>> > out.) Minimizing the bandwidth requires a very specific rise/fall

>> > time

>> and

>> > a hand-crafted sigmoidal shaping function in DSP.

>> > Colonel Sanders closely guards his fried chick recipe, Mrs. Fields

>> > won't reveal what's in her chocolate-chip cookies, and only

>> > selected firmware monks--sworn to secrecy--are privy to Elecraft's

>> > keying envelope coefficients :) 73, Wayne N6KR

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