[Elecraft] More Control Board R1 experiments

[Rod N0RC]

Folks,

I now have R1 set to ~41k ohm, and the overall radio performance is much
better.

Recall I posted about changing R1 to 33K, and that I thought the radio
sounded "harsh" on 40m. That post yielded a good discussion with Ron
AC7AC
and posts by others. After mulling things over I still wasn't satisfied,
so back to the bench....

Still I wished for test equipment to make a better evaluation of
different R1 values. No chance of getting any, but it occurred to me WWV
might
make a good "test signal". It is only 10-15 miles away, and the 10MHz
freq.
produces a SOLID/STEADY S9 signal at my QTH (on my 746pro).

I checked WWV with the K2 and my 33k R1. WOW S9 +20, preamp-off, way too
much. I reasoned that close in strong signals on the amateur bands would
degraded K2 RX performance. But where to set R1? I checked the
sensitivity S-meter specs in ARRL report.  K2 @14 MHz: preamp off, 115
uV to yield S9. 746pro S9 signal at 14.2 MHz: preamp off, 82 uV. So
theory-wise if the 746 is reading S9, the K2 should read a little less.
Again I set about trying different R1 values, and finally settled on
~41k ohms. (not a std value, 220k in parallel with the original 51k).
This value causes the K2's "S9" bar to just flicker. Still a little high
maybe, but I'll take a little extra gain & resulting noise to compensate
for my poor antenna system.

I've been using my K2 for a few days and find this latest change to be
quite useable. The "harsh" sound on 40 is gone. I also notice that often
I now have the pre-amp switched off. Before I would always have the
pre-amp on.

So that's the story here, submitted for peer review. And if the
methodology is worthy, perhaps it can be useful to others.

73, Rod N0RC