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OK, I see there is a problem that can be solved quite easily.

I have 3D printers and Laser cutters, so if you can give me till the New Year, I will work with you all to design and prototype a case between us.

Next you are going to ask the cost, I will just ask for the cost of materials and posting.

So if anyone is interested, let me know.

I can probably find the basic 3D design but I do not have an uncased unit, so I would need local people to me in Manchester, UK. to try and test.

If you think about it, it does not need to be the standard case out already, once we have the fitting for the VNA correct, then we can mod. as we wish, for us.

The offer is there, I just need time to set my 3D units up at home, but after the holidays please.

73 - Les - M0LPB

On Tue, Dec 17, 2019 at 10:40 AM, Dale Parfitt wrote:

Thank you Herb, So much traffic, I missed the specs.
====================================================

Dale,
I'd like to add a correction regarding the display size:

Gabriel indicated in her previous message that a working proto-type is
already available using a 3.2" ILI9341 display. A 4" ST7796S display is
being evaluated as an option by menu-driven switchover. Her team will
make a decision about whether to offer two versions for sale.

Very good Bob... in your post above...

Measuring the bigger ones gives an inductance reading that is too small, since
the distributed capacitance.....

How to measure inductance? Very simple. First, you make up an adapter
so you can connect the unknown to the nano S0.
Calibrate the nano. The next step depends on the inductance. Select a
frequency appropriate to the part, 50 kHz for low frequency parts and up
into the high frequencies for rf chokes and into the VHF and UHF for
straight pieces of wire, etc. Since you can't go below 50 kHz that limits
how large an inductor you can measure.
Select Smith chart for display. Read inductance off the screen. You can
read the resistance and compute the Q. If the inductance is very small,
short the leads and take a reading, which you subtract from the final
reading.
With the leads shorted, the Smith chart should have a dot at the left
edge. With the leads open, at the right edge. If the dot is not at the
edge it indicates a low Q.
As a reality check, open up the span to a reasonable frequency range and
move the marker over the range. The inductance should remain relatively
constant. If you open up the frequency range the chart shows a circle. At
some point the circle intersects the horizontal axis at the self resonant
frequency. With high Q you need to keep the span narrow, as the resonanct
frequency can elude measurement since it's very sharp.
The same procedure works for other components. For cables, it will show
electrical length. The way you measure that is to adjust the frequency so
that the Smith circle, for an open end coax, starts at the right and sweeps
down and around up to the left. Where it reaches the center line on the
left is the frequency where the coax is one quarter wave long. The
deviation from the outside circle indicates loss.
Then you put a small pot as a termination for the open coax and adjust it
until the Smith trace shrinks to a dot in the center. At that point,
measure the pot with an Ohmmeter and it will be the characteristic
impedance.
This inexpensive device is not a toy. It's a sophisticated, well designed
piece of first rate test equipment. No ham with tools should be without
one.
Each time I use mine I learn new ways to use it. You can measure diode
capacitance and, with care, can plot a curve of capacitance vs bias to
characterize it as a voltage variable capacitor to use in a PLL or tuning
network. Just don't apply dc to the vna port. Or any voltage. It has its
own generator, very accurate. You can measure transistor and tube
capacitances as well. Or connectors.
If you connect nothing to the nano it will show a residual reading,
sometimes into the femtofarads (one femtofarad is a thousandth of a
picofarad). I never measured a femtofarad before.
I measure crystals this way. This is tricky, as crystals have very high Q
and you need to keep the span very tiny. You need to know the frequency,
which is generally marked on the crystal. Set the nano as that number for
center and a small span, say a few kHz. The crystal frequency will show at
the left edge but not on a circle due to the lack of frequency resolution.
Keep narrowing the span until you can read frequency as close as you like,
although the resolution isn't all that small.
When measuring capacitors the ESR is indicated on the screen. To measure
ESL you measure the self resonant frequency (curve intersecting horizontal
line) and compute it from the classic formula. Or go to a somewhat higher
frequency and read the screen. Remember that the reading is based on a
simulation of the part as a resistance in series with a reactance.
You measure the distributed capacitance and ESL of a resistor the same
way. With care you can get readings that are very accurate. The standard
used for measuring all of this is the 50 Ohm load you use during
calibration so that needs to be very good for precise readings. My
resistor readings are within about 1% of what my GR bridge and HP 3456A
show.
I know the question was how to measure inductance but I got carried away.
Questions?
Bob K6DDX
On Tuesday, December 17, 2019, 04:59:21 AM PST, Oristo <
ormpoa@...> wrote:

> What's needed to connect my NanoVNA- to my Android phone to use the

NanoVNA- Webb app? Just a usbc to usbc cable?

/g/nanovna-users/message/4970