[Elecraft] SWR difference between 2 different K3's

[Richard Thorne]

I have a strange swr issue I'm trying to resolve.

I have two K3's for an SO2R setup, lets call them K3-A and K3-B.  On 40 
meters the swr that the K3 displays on K3-A indicates what is to be 
expected 1.5:1 at 7.001 and 2.0:1 at 7.105, however on K3-B  the K3 
displays 1.0:1 at 7.001 and 2.7:1 at 7.105.

I'm using the same exact coax to connect to both rigs and I'm going 
directly to ant port 1 on both rigs.  Neither rig has the ATU in line 
(K3-B doesn't even have an internal ATU).  The antenna is a 2 element 
40m yagi.

I've used an external Daiwa swr/power meter which agrees with rig K3-A's 
swr  when connected to either radio.

So it appears that the displayed swr on rig K3-B is giving an incorrect 
reading.

Any ideas?  Is it time to calibrate the wattmeter?

Thanks

Rich - N5ZC