[Elecraft] Final Update To Keying Mod Change

[Bill Tippett]

KI6WX wrote:
 >I've posted a final update to the 180K resistor value
change for the Elecraft Keying Modification.

Hi John,

         I just installed a KAF2, thanks to W4YN, as a solution
to my filter blow-by problem mentioned previously.  Blow-by is
now gone with either AF1 or AF2 (I chose your "Low Ringing"
mod), but it's still there with AF Off, i.e. the passive LPF does
not take care of blow-by products <3 kHz.  BTW, #4119 uses
your crystal grounding technique (less SMT caps) but mine
still has blow-by.

         While I had my Control Board out, I changed R21 to
180k as you suggested.  After doing this <ggg>, I decided
to  completely read your webpage documentation plus
previous posts about key clicks.  I noticed there was some
debate about whether to opt for minimizing <500 Hz products
(Elecraft's mod) or >500 Hz products (your mod).

         I believe you made the right choice for the following
reason.  If I'm <500 Hz from a very strong station, I know
I'm asking for many serious problems (phase noise, IMD,
BDR, etc. in addition to key clicks).  Key clicks <500 Hz
are probably a second-order effect compared to the other
problems I'll have with strong signals.  On the other hand,
it's not unusual to have strong stations spaced at 500 Hz
and up in contests, so I want to minimize clicks >500 Hz for
these situations, assuming I'm a "good citizen" and not
intentionally maximizing my bandwidth to keep others
away (some EU stations are notorious for this in contests).

         Thank you for the many valuable contributions you
have made to improving the K2 for all of us!

                                 73,  Bill  W4ZV