[Elecraft] CW rise time mod

[Dave G4AON]

It's easy, read the revision marked on the board edge in marker pen 
(ouch, couldn't resist that one).

Confusion seems to surround this whole issue, my K3 serial 80, which was 
shipped as a kit in November definitely didn't have a 100nF capacitor at 
C222 as the rise time dropped from 8mS to 5mS when I replaced the 
surface mount capacitor with one from a pack of 100nF ones. Others have 
mentioned the change not having been done on K3s with serial numbers in 
the 300 range.

The safe bet is to check the waveform with an oscilloscope.

73 Dave G4AON
K3/100 #80
-----------------

Elecraft says.....
"Some owners prefer a faster CW keying waveform rise time. The rise time
can be reduced from about 8 milliseconds to 5 milliseconds without
affecting the fall time by replacing capacitor C222 on the K3 main RF
board with a 0.1 uF capacitor. This change will also allow a future
firmware revision to further reduce rise time via a menu entry."

But the schematics of the RF Board Rev. A4 (Sheet 3 of 4), dated
9/19/07, show C222 as being 0.1 already. The instructions recommend
removing the existing 0.1 and replacing it with another 0.1 !! Surely
to reduce the rise time the existing capacitor should be shunted with
another one.

Or do Rev A RF boards have a lower value for C222 than that shown on the
schematic?

73
-- 
David G4DMP
Leeds, England, UK