[Elecraft] Re: Updated Version of Elecraft Keying Mod

[Wayne Burdick]

John,

Thanks for testing this possible change to the keying mod, which looks quite
promising. As you noted, we haven't tested it yet, but it looks like the risk of
going to 180 k is minimal, and I encourage others making the mod to see which
value they like better. If the evidence shows that 180 k is a better overall
choice, we'll consider revising the mod kit.

I have one comment regarding your description of our original mod. You stated
that the rise time using our original value (270 k) was close to 10 ms.
Actually, if you use the traditional definition of rise time, i.e. 10% to 90% of
peak amplitude, your own plot shows a rise time of just over 6 ms. The target
for the mod was 4 to 6 ms, so this is within range. That said, the result with
220 k or 180 k may be preferable, especially if, as you noted, it further
reduces keying bandwidth.

Finally, in our spectral and on-air tests using narrow filters, we observed a
greater degree of keying bandwidth reduction than is apparent in your last plot.
This may have been because we used the old firmware and old circuitry for the
"before" tests, and new firmware and new circuitry for the "after" tests. It
appears that you used the new firmware for all tests. Is that correct? Also, our
tests were based on sending a continuous stream of dits at 30 WPM rather than on
a single dit. We averaged over a long period. In theory, this shouldn't produce
different results, but I mention it in case you want to compare the two methods. 

73,
Wayne
N6KR

"John, KI6WX" wrote:
> 
> I updated my changes to the Elecraft Keying Modification.  The modification
> description is available at
> http://home.pacbell.net/johngreb/KI6WX.html

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