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Old January 18th 04, 08:45 PM
Thierry
 
Posts: n/a
Default SWR read to TX or rather to the antenna ?

Hi,
It seems well-known that the SWR value that you read on an external meter or
an antenna tuner is NOT the value measured between itself and the antenna.
The SWR value "picked-up" and that you can change is the one measured
between this meter or tuner and the transceiver (or the linear amplifier but
we consider it as a black box if you use it properly).

But recently I experimented the burning of my PL due to a high SWR, thus
high current, and moisture and the end of the line (really, see image of
PL's here http://www.astrosurf.com/lombry/qsl-...sion-line2.htm, end of
page ).

The distance between my RTX and SWR reader is short, about 1 m. But there
are about 15m between the SWR and the feed point of my antenna where I had
the problem.

So I would like to know if an SWR meter does only read the value upstream or
if the properties of the feedline to the antenna does not influence is
reading.
At first sight it does as during this problem I had a SWR 4:1 on the
external SWR-meter. This value didn't come from the RTX side which built-in
SWR displayed a VSWR 1:1. It really came from the other side, to the
antenna, thus contrary to what I think and what is usually stated about the
functioning of this device...

Can someone explain me this ?

Thanks in advance

Thierry
ON4SKY