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Greetings,

I became concerned about the possibility of loosing the tiny
SMA precision SOL references that came with my nanoVNA especially
considering portable field use. I found the small calibration box shown in
the attached photos was easy to build. With parts bought online from
AliExpress sellers the cost for the parts was less than $15. I find it
relatively easy to use compared to handling and taking care of the
individual tiny SMA references. The box is easier to handle and keeps all
the references together in a single package.

I also added a knurled connector for through calibration and/or
connection to the device under test (DUT). As shown in one of the photos I
very carefully made a puddle of JB Epoxy Weld around an SMA nut aligned
with the front panel hole to provide a threaded socket for the connector
storage. The knurled through connector is easy to remove and remount. With
the knurled grip it is also easier to handle when connecting to a DUT
compared to the more typical free hanging through connectors.

For critical measurements at frequencies above VHF it would be
important to use the same bulkhead female-to-female through connector type
as those mounted in the box for the references for connection to the DUT.
The bulkhead through connectors used here for the box front panel are
slightly longer than the more typical free floating through connectors.
Thus use of shorter connectors for connection to the DUT would shift the
reference plane slightly which could significantly skew the results at
higher frequencies.


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Best Regards,
tma
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Best Regards,
tma