[Elecraft] Fwd: New Sherwood report

[Paul Christensen]

> Yes 99% of all CW stations clicks at the "break" side.

That's an unusually high percentage from what I recall seeing in the QST 
Product Reviews during the past twenty years.  So, I looked at the CW 
waveforms of the more notorious transceivers.  It seems to be an even mix 
between leading edge and trailing edge issues.

In looking at the Ten Tec Omni Six Plus, it's the leading edge with the 
sharp slope and discontinuity that creates clicks.  I drafted a fix for that 
back in 1998 and it appears on the N1EU website.

The ALC problem with the FT-1000MP series is more problematic on the 
trailing edge, although from the 1996 QST review, the initial keyed element 
has a severe problem at the leading edge, then followed by a problem at the 
trailing edge with successive keying.  That occurs as the ALC is trying to 
stabilize.

On several other transceivers, I noticed significant dit shortening and 
discontinuities on the initial keyed element, then the rest in the series 
look fine, again as the ALC stabilizes. The FT-1000D shows a significant 
problem on the leading edge, with dit shortening occurring on the first dit. 
Dit shortening is not directly attributed to ALC.  The root cause of that is 
unrelated.  The K3 has a slight bit of dit shortening, and about 3 msec of 
compensation from an external keyer helps to restore the envelope to the key 
closure time, although deciding exactly how the contact closure and RF pulse 
time should match can result in a spirited debate, owing to the required 
rise/fall time.

I would tend to throw out problems that only exist with the initial keyed 
element so long as the remaining series looks fine.  These transceivers 
consume a lot of bandwidth very briefly, then the bandwidth dissipates.  My 
TS-480 comes to mind as it has a sharp leading edge with a slight power 
spike on the leading edge of the initial element then disappears with 
continued sending until there's a long pause.   So, based on what I am 
seeing, the ALC problem is pretty well evenly distributed between the 
leading and trailing edge issues.

Paul, W9AC