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<p>Both ideas/approaches are unworldly. While the implementation of
a VNA software is no big deal, a hardware reflection bridge has to
be inserted and in particular calibrated.</p>
<p>But even when you get a reasonable result of R and jX at your
radio input, it's not enough information for an automatic tuner:
the tuner's position in the feedline and the length of the
feedline determines the necessary transformation. It would be much
easier to utilize the SWR, e.g. available at a bidirectional
coupler, used for the PS feedback loop.</p>
<p>73, Helmut, DC6NY<br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">Am 03.11.2020 um 17:55 schrieb Scott
Traurig:<br>
</div>
<blockquote type="cite"
cite="mid:CAGK9zXpWWS2kwN2TWh52qqX55kfOpT-4g7XoJEFyAGkDrT87-w@mail.gmail.com">
<pre class="moz-quote-pre" wrap="">***** High Performance Software Defined Radio Discussion List *****
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<div>There was work in this regard done a long time ago but it
is hopelessly stale and it also requires additional hardware:</div>
<div><br>
</div>
<div><a href="https://openhpsdr.org/wiki/index.php?title=VNA"
moz-do-not-send="true">https://openhpsdr.org/wiki/index.php?title=VNA</a><br>
</div>
<div><br>
</div>
<div>It would undoubtedly be easier to adapt a NanoVNA. Not only
is the hardware ready to go, the software is simpler and a lot
more accessible. It would be easy to embed in a home brew
tuner:</div>
<div><br>
</div>
<div><a href="https://openhpsdr.org/wiki/index.php?title=VNA"
moz-do-not-send="true">https://openhpsdr.org/wiki/index.php?title=VNA</a><br>
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<div><br>
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<div>Finally, it's worth noting that the only tuner on the
market that actually makes a complex impedance measurement and
jumps right to the exact answer in one step is the MFJ-939. If
MFJ made a legal limit version of that tuner I'd buy it in a
heartbeat.</div>
<div><br>
</div>
<div>73,</div>
<div><br>
</div>
<div>Scott/w-u-2-o</div>
<div><br>
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<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Nov 3, 2020 at 11:32
AM <<a href="mailto:radio@netins.net"
moz-do-not-send="true">radio@netins.net</a>> wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex"><br>
Pure signal uses one RX channel to provide feedback.<br>
<br>
Is it possible to use an RX channel to determine just the
phase and <br>
resistance of the RF signal in the antenna system feed
point? If so, <br>
this could be used to automate a home brew antenna coupler.<br>
<br>
John, W0GN<br>
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