[Elecraft] CW rise time mod

[Ken Wagner]

Hi David:

I measured C222 *in place* with my aade cap checker and it measured ~1 
uF(actually 0.965 uF)... not the 0.1 in the schematic. I'm guessing that 
the schematic available for download is not current with production. 
Someone else here mentioned that  C222 was 1 uF, but I don't remember 
who it was.

73,
Ken K3IU

David Pratt wrote:
> 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