[Elecraft] KAT100 and external watt meter question

[Stuart Rohre]

Most external watt meters are designed to go between a rig and a tuner, as
they are ONLY accurate in a 50 ohm matched line.  Any one used downstream
toward the antenna from the tuner, in the transmission line that has SWR is
suspect of not reading under its expected impedance requirements to read
accurate SWR.  On a tuned line, after the tuner, the line plus antenna is
being tuned as a system and will have swr on it, unless the line
accidentally matches the antenna impedance exactly on some band(s).
That only matters in that coax has higher losses when operated with SWR
higher than 1:1 matched condition; as in a doublet used on multi bands.

When you tune a transmatch, the 50 ohms is made to appear at the transceiver
side, and it may be something vastly different on the transmission line/
antenna side.
72,
Stuart K5KVH