Envelope-to: dave@picks.force9.co.uk
Delivery-date: Fri, 23 Sep 2005 10:36:01 +0100
Message-ID: <B333AB0EF6D4D4118BAF00508BAED8EA088DA77E@mms12014.stv.uk.astrium.corp>
From: "OSBORN, Chris" <Chris.OSBORN@astrium.eads.net>
To: "'rsgb_lf_group@blacksheep.org'" <rsgb_lf_group@blacksheep.org>
Date: Fri, 23 Sep 2005 10:29:00 +0100
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Subject: LF: RE: RE: DFCW
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	Many thanks Dave,

	All noted with interest and I should have no trouble now.
	I saw your CQ on DFCW last night, must have been about 8 'ish.
	I was tweaking my new RX and you were of course a colossal signal.

	73 Chris G3XIZ

-----Original Message-----
From: Dave G3WCB [mailto:ganymede444@btopenworld.com]
Sent: 22 September 2005 09:12:PM
To: rsgb_lf_group@blacksheep.org
Subject: LF: RE: DFCW


Hi, Chris.

I use the program "QRS v4.02" from ON7YD to send both QRSS amd DFCW. It's
very easy to use and configure, and you can do useful things like alter the
inter-character spacings, flip DFCW mark and space, etc. You need to build a
1-transistor interface/level shifter to key the transmitter, but the circuit
is contained in the "Help" documentation that comes with the program.

http://www.qsl.net/on7yd/software_main.htm


If you can't get enough swing with a vari-cap, you can use a 1N918 or 1N4148
Si diode as a switch, and use it to switch a trimmer capacitor across the
crystal. I use a crystal in the 3MHz range in a Colpitts configuration, and
the DFCW control signal switches a 3-30 pF trimmer across the crystal. For
DFCW3 speeds, about 3 or 4 Hz shift is all you need. If you go to DFCW10 or
longer, you need only about 1 Hz or less shift.

The convention seems to be that the dash is the higher frequency.

73 Dave G3WCB IO1RM

-----Original Message-----
From: owner-rsgb_lf_group@blacksheep.org
[mailto:owner-rsgb_lf_group@blacksheep.org]On Behalf Of OSBORN, Chris
Sent: 22 September 2005 13:57
To: LF Group (E-mail)
Subject: LF: DFCW


	My new LF TX is nearly finished and I would like to add the option
of DFCW.

	I was thinking of just placing a varicap diode in parallel with the
crystal and thus pulling the frequency
	for achieving the dots / dashes.

	Can someone direct me to a circuit diagram and software to achieve
this ?

	73 Chris G3XIZ


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