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Message-ID: <a3wmgEAgs+Y3EwFJ@dennison.demon.co.uk>
Date: Sun, 13 Jun 1999 18:32:16 +0100
To: rsgb_lf_group@blacksheep.org
From: "Mike Dennison" <mike@dennison.demon.co.uk>
Subject: Re: LF: Disappearing 'dits'
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Alan.Melia@btinternet.com> writes
>Can it be that the Q's of aerials and tuning are such that 
>the TX is not rising to full power during a 'dit'?? I find that a bit hard to 
>believe.

The idea of an LF antenna being too narrow for CW is a myth, certainly
for the very lossy tiny-fraction-of-a-wavelength antennas we use. With
practical losses of several ohms in a loading coil and tens or even
hundreds in the earth system, bandwidths are relatively wide.

I measured my Marconi, and the 3dB points (antenna current down to 0.7
of maximum) are 5.5kHz apart - easily enough for an SSB signal and
nowhere near the 100Hz or so you would need to slow down a dot. 

It would be interesting to hear what others make their 3dB bandwidths.

As for adapting CW technique to the propagation and receiver bandwidth,
this is quite common as you say. I find that those working 160m DX (real
DX like W6 or JA) tend to lengthen the gap between elements (dots and
dashes) because the path tends to fill them in - is this a sort of
ionospheric ringing? I have set my own keyer weighting to have longer
than normal gaps.


-- 
Mike, G3XDV
www.dennison.demon.co.uk/activity.htm