[Elecraft] FW: K2/100 SWR accuracy

[Carl Strode]

Here is a bit of follow up info, and preliminary results.

I got a bunch of input and suggestions - all are appreciated.

The covers are off, and the K2/100 is spread out all over my shack.  The 
setting of C1 was checked, and I do now recall that the "sweet spot" is 
really hard to find using the first method in the manual.  The range 
over which an indicated 1.0 SWR is displayed is much to large.  I used 
the alternate method of measuring the TP4 null voltage, and seem to have 
a bit better results.  My first choice of a DVM was one with 2-1/2 digit 
resolution (e.g. the smallest digit displayed is an integer millivolt).  
Then I tried a higher-end Fluke meter with two orders of magnitude 
better resolution.  I found the adjustment of C1 could be significantly 
improved.  This is not possible using the K2 SWR indication only, or 
using a cheap DVM with typical hardware store accuracy

I am still awaiting the arrival of some non-inductive resistors so my 
wattmeter settings can be refined.  In the meantime, I have been 
tweaking R26 and R27 in an attempt to get things working a bit better.  
The one problem I am still rassling with is the K2s tendency to change 
its power output in the tune mode.  Just as I am about to zero in on a 
power setting - lets say 30 watts as indicated by an external and 
trusted wattmeter, the actual power output from the K2 jumps around - up 
and down, back and forth - by several watts.  I am left chasing the 
setting allover the place from 20 to 40 watts.

This is really driving me nuts!    I suspect this is what may have led 
me to buttoning the K2 up a couple of years ago before I had done my 
best calibrating power output and SWR indications.

Carl WA7CS