I've just completed alignement of my KAT2 and am a bit dismayed by its SWR
accuracy.
I feel pretty confident that I found the true dip in C55 at a value of 12.
I then aligned the forward power (R1) using an OHR WM-2 that was aligned on 40m
against test equipment. The 50 Ohm dummy load I'm using reads a flat 1.0:1 up
into the 2m region on an MFJ-259B. I'm fairly happy with the forward
calibration which yielded the following results:
BAND K2 WM-2
160 4.4 5.0
80 4.6 5.0
40 4.9 5.0
30 5.2 5.0
20 4.9 4.9
17 5.0 5.0
15 5.1 4.9
12 5.5 5.0
10 5.6 5.0
I initially calibrated reflected power (R2) by measuring the
wiper-to-ground resistance on R1 and setting R2 for the same wiper-go-ground
resistance. The reflected calibration results range from 1.0:1 on 160m to 1.2:1
on 10m into the 50 Ohm dummy load. However, the SWR readings I see when using a
25 Ohm dummy load (confirmed on MFJ-259B) aren't very good. The KAT2's 25 Ohm
dummy load readings range from 1.7:1 on 160m to 1.2:1 on 10m.
Given the preceding results, I decided to set the reflected adjustment (R2)
to show 2.0:1 on 40m into the 25 Ohm dummy load. This time, the results varied
from 2.1:1 on 160m to 1.3:1 on 10m. I have considered going back and
readjusting R2 to show an average reading of 2.0:1 across the bands into the 25
Ohm load (higher than 2.0:1 on 160m, lower than 2.0:1 on 10m -- a compromise).
Is the accuracy displayed above typical of the KAT2? If not, maybe I need
to go back and reevaluate my C55 calibration (although I felt pretty confident
that it is correct).
Thanks, Michael N9BDF, K2 #4137
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