> increases the band width so you got a wide signal. oops
> forgot to add the
> keying speed into the mix. that also adds to the band
> width.
Keying speed, contrary to popular misconception, does not
change bandwidth. The rise and fall shape and duration sets
the ultmate bandwidth whether you send one dash a year or
1000 dots a minute.
That popular myth probably comes form the fact rise and fall
duration limits the ultimate speed.
The CW signal from a transmitter with a clean carrier has
sidebands only when power level is changing. The two states
of fully off and fully on occupy no bandwidth, only the
changing level does. The slope and amount of level change in
the transition determines the bandwidth, the speed only
changes how often the sidebands appear. If the change period
is too slow it limits ultimate speed because a zero or
maximum can't be reached in the time allowed by the key, so
there is a limit to speed caused by finite bandwidth.....but
not the other way around.
http://www.w8ji.com/what_causes_clicks.htm
> In the old days using cathode keying we simply put a
> condenser across the
> keying line.
Yes, but that would primarily reduce interference to
Broadcast radios by local clicks radiated by key leads from
the arcing in our key contacts. The rise and fall shape was
difficult to control and required R/C or L/C circuits in
several stages and a linear PA unless final shaping was done
in the PA.
Check out this waveform!
http://www.w8ji.com/heathkit.htm
and that is with grid block keying.
73 Tom
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