Posted by
P.B. Christensen on
Dec 01, 2009; 11:58pm
URL: http://elecraft.85.s1.nabble.com/K3-killing-RX-key-clicks-tp4093607p4097144.html
> The 'RC rise/decay' wave shape that was in the handbooks for many years
> is actually a *bad* shape because it has a very sharp corner on key-up.
Ian, *bad* may be a bit too harsh. The League's optimized envelope was
described during a time when only simple R/C values were used to develop a
keyed envelope. I'm not sure how one would have produced an economical
Blackman-Harris or raised cosine function until say...the early to mid '90s.
How would you have done it? Probably the only solution at the time was to
set leading and trailing edges produced by the R/C network so soft that
they're painful to copy.
Myself, I actually prefer the R/C keying as shown in those issues of the
ARRL Handbook for reasons that Ron cited. What I like is a slightly fast
leading edge, but an exponential trail of the falling edge. Irrational?
Yes, I'll admit it. My favorite rig to listen during a CW rag-chew is
either the Drake T-4XC or TR-7. Both produce nearly identical keyed
envelopes. And, yes, neither are optimized for minimal bandwidth. However,
with just a bit of help on the leading edge, keying bandwidth can be kept
reasonably narrow.
Paul, W9AC
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