[Elecraft] K3 SWR Accuracy - reprise

[Paul Christensen]

> That assumes there is no RF on the exterior of the coax and the SWR
> sensors are ideal. Neither is the case and from personal experience I
> can tell you that the swr meters will change readings based on coax 
> length.

The SWR *reading* may change as a function of coax length when current is 
present on the outer conductor, but as Phil states, the actual line SWR does 
not change, neglecting any line loss.  In a mismatched condition, the Z 
measured at the line input does change with line length and as F increases, 
it takes smaller changes in line length to see changes in input Z.

To deal with the problem Eric describes, I use choking line isolators 
between the transceivers and amps, immediately after the amp, and depending 
on the antenna type, again at the antenna feed point for most antennas with 
a coaxial feed point.

Paul, W9AC