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<p>Martin, thanks for your post.</p>
<p>It's John, W0GN, who is suffering from connection problems
between HERMES and VNA software after switching from win7 to win
10, not me. Hermes VNA 1.6.0 as well as HamVNA 1.1 works fine on
my win 10 machine.</p>
<p>Maybe it can be in the interest of others to reply on your
further comments:</p>
<p>Of course you have to use HERMES exclusively with direct access
to the SMA ports for VNA operation. Moreover I would recommend to
connect 10 dB SMA pads to the port. A precise calibration set for
open, short and 50 ohms and a good reflection bridge is essential
for serious measurements. Crosstalk or leakage is not so bad as
you mentioned. Acceptable and repeatable values are between 80 dB
and 90 dB. That's far more than a ham needs.<br>
</p>
<p>The 900 Mhz-NanoVNA and the new 3 Ghz-NanaVNA2 show approx. 30 dB
less dynamic range than HERMES! But they have a huge frequeny
range and you can't compare them directly. These cheap Chinese
stuff - employing western chips of AD and ST - are really nice
tools for hamradio apps, but not for higher standards.</p>
<p>73, Helmut, DC6NY</p>
<p><br>
</p>
<div class="moz-cite-prefix">Am 07.12.2020 um 10:10 schrieb Martin
Emmerson:<br>
</div>
<blockquote type="cite"
cite="mid:CAKYbmMTLJGo9=-qSjD+aJ5QA2kTQ9E5k05DWfoZngmzSejKOzw@mail.gmail.com">
<pre class="moz-quote-pre" wrap="">***** High Performance Software Defined Radio Discussion List *****
</pre>
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<div>I am not sure what version of the VNA software for Hermes
is causing your problem but a<br>
</div>
<div>long time ago around 2013 I did some work on the original
VNA code for Hermes as it had <br>
</div>
<div>problems connecting.</div>
<div>I did this in conjunction with Phil Harman and I ported
some code from the "KISS Konsole" and</div>
<div>with the addition of repeated tries to connect I got it
working reliably and I think this version</div>
<div>was published and had my callsign on the about box.</div>
<div>Then I found this version:</div>
<div><a href="http://www.dxatlas.com/hamvna/"
moz-do-not-send="true">http://www.dxatlas.com/hamvna/</a></div>
<div>Which worked reliably with the Hermes and had no problems
with connecting but the remaining</div>
<div>problem is that while the Hermes is an excellent SDR
transceiver it is not a very good VNA!</div>
<div>This is because leakage between the TX and RX terminals,
limiting its dynamic range. <br>
</div>
<div>Made worse if you have the necessary RX/TX switching
connected. Direct connection to the</div>
<div>Hermes SMA connections, it is just acceptable.</div>
<div>I was so impressed with HamVNA that I modified the code to
also work with my dedicated N2PK</div>
<div>VNA.</div>
<div>Then I found NanoVNA available on eBay for less than £50
which goes right up to 900MHz and that</div>
<div>is now my VNA of choice.</div>
<div>Just my view on the VNA for what it is worth.</div>
<div><br>
</div>
<div>73's</div>
<div><br>
</div>
<div>Martin G3OQD.<br>
</div>
<div><br>
</div>
</div>
<br>
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