I have always understood that the SWR on a line will be almost the same
wherever it is measured (it will increase slightly as you approach the
load due to losses). It is the impedance of the load as transformed by
the line that changes.
One thing that I've noticed is that SWR meters often differ when the SWR
is low, because the amount of reflected power is very small, and diodes
are often nonlinear dealing with small signals. The difference between
an SWR of 1.1:1 and 1.2:1 is a very tiny amount of reflacted power.
73,
Vic, 4X6GP
Rehovot, Israel
Formerly K2VCO
http://www.qsl.net/k2vco/
On 5 Nov 2016 04:43, Ron D'Eau Claire wrote:
How much coax is between the K3 and P3 monitor? Only a few feet will create
a growing error as the SWR increases, since the standing waves on the
coaxial line produce different readings at different points along the line.
If you want to compare the SWR meters in the K3 and P3, be sure the P3
sensor is mounted directly on the K3 without a length of coax in between.
Even so, the K3 SWR sensor will be "looking" at the P3 sensor through the
KAT3. Although it is bypassed, the older KAT3 ATUs still routed RF through
them on its way to the K3 rear-panel ANT connector.
Even so, as Fred pointed out, there will be differences since SWR meters are
no "precision" devices because they don't have to be. The K3 is quite happy
at load SWRs up to 2 or 2.5:1 and even above that the amplifier will protect
itself.
73, Ron AC7AC
On 11/4/2016 6:59 PM, [email protected] wrote:
I recently installed the TX monitor in my P3 and have a discrepancy
with the SWR reading between it and the K3
with a dummy load connected the P3 and K3 read 1.12 and 1.0
respectively a level of error that is to me quite acceptable.
however when connected to an antenna I will see the SWR on the K3
often close to 1:1 when the P3 will show up to a 1:2. as the SWR
climbs above 1:2 on the P3 the K3 reading will track it fairly
closely but about a level of 1 below. example
K3 1:1 P3 1:2,
K3 1:1.5 P3 1:2.5
K3 1:2 P3 1:3 and so on
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