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Date: Wed, 25 Aug 2004 11:51:16 +0200
Message-Id: <F5878FE035382745BF8928154A07D3D1938AF7@TNS-FBU-2E-006.corp.telenor.no>
Thread-Topic: Key Clicks
Thread-Index: AcSKh9oQNQVb1CxFQQq0zGZHTgjB0wAAJNhw
From: jan-martin.noding@telenor.com
To: rsgb_lf_group@blacksheep.org
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Subject: LF: RE: CW Modulator to avoid Key Clicks
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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
---
J M Nøding, LA8AK
Telefon 9077-7126 (QTH: 0047-380-87178)


-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of Hugh M0WYE
Sent: 25. august 2004 11:33
To: rsgb_lf_group@blacksheep.org
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