Hi Stefan,
>But why did you
>write that email at 10 hours after the QSO took place? When beeing in
>the shack, i'm mostly watching incoming emails
I was unsure if you would do that, so I decided to resort to listening to
the
interesting stuff you were talking about (antennas,drinks, girls...:-) ).
>And they all use true class D PAs.
>Somehow most of the active CW stations do not have a "clean"
>signal and
>those who have a clean signal are not QRV :-)
I have no hands-on experience with class D PAs,only class B,
but it seems that key klicks with class D are NOT inevitable,see
http://amfone.net/Amforum/index.php?action=printpage;topic=28417.0
Quoting from there:
---------------------------
"...Well, I know from the tube days that you couldn't just key the drive to
a tube class C final - major key clicks. The same goes for class C, D or E
solid state amps. You can't just key the drive - same problem - key clicks.
This is because the shape of the keying waveform is not preserved in class
C, D, E or F due to the fact that the amplifiers are not linear (nor should
they be!!).
"Overshaping" of the input waveform is NOT recommended with MOSFETs because
they have so much gain. A parasitic can result when the MOSFETs are
operating in the linear region. And if you are using digital drive (which
is a better way of driving MOSFETs) you can't even overshape the input.
So, what is generally done is to key the drive and key the high voltage
using a series element (a MOSFET or MOSFETs in parallel) - with the input to
the series element being a good CW rise and fall time. The series element
is most easily created using a source follower and some type of pull up with
controlled rise and fall times. Easy to do with simple R/C circuits. "
------------end of quote--------------------
So my main point is that it should be doable for a serious homebrewer to
generate a (nearly) key klick free CW signal also with a class D amp.
The stronger the signal the more important is a clean spectrum.
>Did you listen by ear or did you use a CW decoder?
My aural limit is at about 12-15wpm and you were going near 30wpm...
My compliments!
73
Clemens
DL4RAJ
>-----Original Message-----
>From: [email protected]
>[mailto:[email protected]] On Behalf Of Stefan Schäfer
>Sent: Sunday, August 18, 2013 2:16 PM
>To: [email protected]
>Subject: Re: LF: QRM on 472.5kHz
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