Have experimented very much improving key-clicks in the 80's, such "AM
modulator" for CW-transmitter is shown on my page
http://home.online.no/~la8ak/d31.htm
The modulator is driven from a lowpassfilter. In this case the exciter of PYE
Westminster (or T30FM) is keyed and the PA is supposed to be quasi linear
(BGY36 power module for the application)
73
Jan-Martin
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J M Nøding, LA8AK
Telefon 9077-7126 (QTH: 0047-380-87178)
-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Hugh M0WYE
Sent: 25. august 2004 11:33
To: [email protected]
Subject: LF: Key Clicks
Good morning all,
I keyed my original LF TX with a relay - crude, but it got me on the air.
I know many designs just filter the keying waveform to "round off the
corners" of the envelope.
But I read that the best envelope shape is a "Gaussian waveform". This
produces the smallest sidebands.
[ http://fermi.la.asu.edu/w9cf/articles/click/click.html and lots of other
stuff ]
RC and LC filter circuits produce exponential waveforms, although the
waveform diagrams that accompany these circuits in the texts often make then
look as though they produce a gaussian waveform.
My question is ...
Is there a circuit that will produce a nice "gaussian wavform" that I could
feed into an AM modulator to produce really clean CW - or is there no such
thing ?
73
Hugh M0WYE
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