Hi Steve,
http://www.n9vv.com/k7qo-a-b-keying.html
that paper seemed pretty good.
In that paper there is some mention of "the halfway point" in an element
being the dividing line. If I am sending an "F" for instance, and I have
the dit paddle closed at any time after the halfway point in the dah,
then the trailing dit of the "F" will get sent. And if I release the dit
paddle before the halfway point of the dah, then the trailing dit would
not be sent, and a "U" would be sent, instead of an "F". At least that
is the way I understand what he is saying.
If every keyer operating in Mode B operated exactly this way, then we
would never notice any difference from keyer to keyer, and there would
be no need for anyone to "adjust" to different mode B keyers. There are
enough of us that have noticed a difference that we can make the
resonable conclusion that not all Mode B keyers operate exactly the same.
I suspect that there are subtle timing differences in various Mode B
keyers, such that the "halfway point" is not at exactly 50% through the
dah. Dividing points in a dah may more conveniently occur at the 33.3%
and 66.7% times within a dah, because the basic minimum element duration
of a dit (or a space between elements) is 33.3% of a dah. I wonder if
some Mode B keyers actually use 33.3% or 66.7% instead of 50%.
DE N6KB
|