RadioBanter - View Single Post - SWR will change with Source Z if you measure AT the Source

August 22nd 03, 10:32 PM

(Richard Harrison) wrote in message ...
Dr. Slick wrote:
"Does the SWR change as you change the source impedance?"

"SWR" as Reg notes is an indication of match condition when measured at
the transmitter output. There may not be enough line for maxima and
minima.

Loading a transmitter usually increases the current drawn by the final
amplifier. This lowers
its output impedance in most cases. As "SWR" is an indication of
mismatch, you can`t change one impedance without changing the "SWR",
unless you make a corresponding change in the other impedance in the
match. Corresponding is a significant word.

Best regards, Richard Harrison, KB5WZI

Well, like i said, the SWR will change as you change the source
Z, but you have to measure it before the reflection occurs (the SWR
must be the same Z as the source, and must be right at the output), or
you won't measure it "downstream".

Slick