Bob McGraw - K4TAX
I suggest setting the TUNE power to 25 watts or so and allowing the KAT500 to do its routine to resolve a match. This will reduce the value of the CMC which can be seen by and confuse the KAT500. With a 1.5:1 SWR on the feedline, unless it is lossy line, I wouldn't worry about it. Some of the SWR is likely due to the 5 port antenna switch.
My KAT500 and my KPA500 and my in-line power/SWR meter all showed different SWR values on 6M.
A final comment, be sure each piece of station equipment is bonded to a common point with dedicated jumpers. My station power supply is my common point.