"Ian White, G3SEK" wrote -
No - I meant exactly what I said. The meter can only indicate the
rho/SWR of whatever is connected downstream (load side) of the meter
itself.

==================================

(1) I'm sure we are agreed our meters will correctly indicate Rho and SWR
only on 50-ohm lines.

(2) Insofar as the meter is concerned the transmitter's load impedance is
the input impedance of the transmission line between the meter and the
antenna. There may or may not be an intervening Z-match network.

(3) Insofar as the transmitter is concerned the line between meter and
antenna can be ANY impedance. It is desirable only that line length with its
Zo transform the antenna input impedance to somewhere near to 50 ohms (Like
a G5RV on 14.15 MHz). If things become difficult then a Z-match can be
inserted. Once we have selected Zo for this line we are no longer
interested in its SWR. And if we WERE interested a 50-ohm SWR meter would
be incapable of correctly measuring it.

(4) Note that when a Z-match is located at the transmitter end of this
feedline, and varied, the actual SWR on this line cannot change - yet the
SWR meter responds readily to the Z-match settings.

(5) The only line which, ideally, MUST be 50 ohms coax and have a small
SWR, certainly if it is of appreciable length, is that between the meter and
the transmitter. Otherwise the load directly presented to the transmitter
would not be 50 ohms. Any other impedance would transform the 50 ohms seen
immediately on the antenna side of the meter to some other value.

(6) It is the SWR on this line which the meter indicates. (If this line is
NOT 50-ohms then the meter incorrectly indicates the standing waves on it.
Which is what I said before and a lot of people disagreed. Not that a false
indication is of great consequence when it is the incorrect choice of line
Zo where the problem arises.)

(7) In practice at HF the length of this 50-ohm coax is often negligible.
The meter is often inside the transmitter box. As the misleading idea of
standingwaves on this short, even zero-length coax is nonsense the name of
the instrument should be changed to TLI. (Transmitter Loading Indicator).
Which is all that it is!

( 8) Then the topic of conversation on this newsgroup can then diverted
back to where it belongs - the far more important non-measured SWR on the
main feedline to the antenna.
----
Reg, G4FGQ