Roger, that's right - I forgot that the VNA was being used and not a
directional line coupler.
The results are not surprising. However, it would be interesting to
observe SWR at the VNA with random changes in line length between the VNA
and the tuner when he used: (a) the 4 ft. section between the tuner and
75-ohm resistive load; and (b) a 19-inch line section between the VNA and
tuner. If I have his facts straight, that showed an SWR value of 1.8:1.
If Gary was trying to use the tuner to emulate an amplifier input network,
then what we want to see is measured SWR sensitivity to change as a function
of line length between the VNA and tuner when a non 1:1 SWR is present
between the tuner and load.
Paul, W9AC
-----Original Message-----
From: Roger D Johnson
Sent: Tuesday, January 13, 2015 9:21 AM
To: Paul Christensen
Subject: Re: [Amps] Input SWR revisited
The VNA does not measure the VSWR on the line. It measures VSWR at the
input to the VNA unless you do a cal at the load end of the line to remove
it's
effect.
73, Roger
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