[Elecraft] K3 - SWR Indication

[Paul Christensen]

> Other than SWR reduction due to cable loss, the SWR meter should read the
> same SWR regardless of where it is on the coax.

Some reasons for changes in indicated VSWR as measured at different points 
along the line:

1) Line loss.  As line loss increases, VSWR will show a better reading 
closer to the source than at the load, irrespective of the line-to-load 
mismatch;
2) The bridge/directional coupler's designed line Z does not equal the 
characteristic Z of the line and the load is a complex Z.  (Example: Bird 43 
with 50-ohm line section being used on a run of 75-ohm line where the line 
is terminated into a load with a Z value other than 75 ohms); and
3) Line current imbalance.  Normally, current on the outer surface of the 
inner conductor should equal the current on the inside surface of the outer 
conductor.  Current flow on the outside of the outer conductor will cause 
line imbalance and incorrect VSWR indications, depending on the magnitude of 
current on the outer surface of the outer conductor.

Paul, W9AC