Reg Edwards wrote:
To anybody interested.

We have a HF Transmitter + 50-ohm coax + SWR meter + Tuner + Feedline of any
Zo + Antenna.


Suppose it is all tuned-up and ready to go. The transmitter is loaded with
exactly 50-ohms resistive.


Now change the 50-ohm coax to shorter length of 75-ohm Zo.


As everybody agrees (after perhaps a little meter recalibration) the SWR
meter indication will not change. BUT THE TRANSMITTER WILL NOW BE
INCORRECTLY LOADED.


Where does the inconistency lie ?

The inconsistency lies in failing to meet the requirement that:

1. the correct load impedance for the transmitter

*and*

2. the system reference impedance for which the SWR meter was calibrated

*and*

3. the impedance of that connecting line

....must all be the same.

See the longer reply to your other message. (This is yet another way of
saying the same things.)


Does it lie in the change in effective
source impedance?

That's the one place where the inconsistency definitely does *not* come
from.


--
73 from Ian G3SEK 'In Practice' columnist for RadCom (RSGB)
Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek