Sorry Jim. You are indeed correct about the feedline SWR. While
there are other SWRs within the radio, they aren't of much interest.
However, these radios do report a SWR in the UI, and that is
what I was referring to. Since a naive user might look at that
figure and say, "The SWR is 2. The antenna must be good.", it is
important to know that the tuners can produce a low figure on
that meter with nothing connected to the antenna connector.
73 Bill AE6JV
On 8/30/17 at 11:25 PM, [email protected] (Jim Brown) wrote:
Please don't perpetuate that myth, Bill. Tuners do NOT reduce
the SWR unless they're at the antenna end of a transmission
line. The SWR exists on the transmission line, and it is
determined ENTIRELY by the match between the transmission line
and the load.
What tuners at the rig do is get the rig to put power into the
tuner (and hopefully, onto the transmission line). If the SWR
is high without the tuner, it is equally high WITH the tuner.
Depending on the cable, the frequency, and the SWR, much of the
power that the rig puts into the tuner gets to the transmission
line, but is turned into heat by the SWR in the line and
doesn't get to the antenna.
A better way to talk and think about this is to say that the
tuner can match a wide variety of loads to the transmitter
sufficiently well that the rig can pump the maximum power from
its output terminals, whether it's feeding a short wet string
or a nice long wire we've launched into a tree. And if there's
no transmission line, SWR has no meaning! So SWR is the wrong
way to talk and think about it.
73, Jim K9YC
On 8/30/2017 10:15 PM, Bill Frantz wrote:
My experience with the tuners in both the K3 and KX3 are that
they will reach an acceptable SWR with anything. I always
check the antenna when they take a long time to reach a match.
(I.e. lots of clicking.) Most of the time I find I am trying
to match an open antenna connection.
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