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Her are some pictures.

Checked your picture, black and white are not made by us, but it seems that your black version uses the same circuit as ours, we only found a little difference on the PCB, as long as the test is normal, it should not affect the use .

hugen

All,

I'd like an inexpensive calibration set (open, short, 50 ohm load) for BNC (M&F) Any one seen such??

Larry, K4MLA

Calibrating to the end of a cable was SOP in the lab I ran and every
time some one would tell me it introduces error I'd give them what ever
time they needed to prove it. They all failed in their assertions
as did I when I had that assumption in my head many years before.

Your data is as good as the cal to the plane of the cal. Even with
45ft of RG400 at 400mhz it worked.

The only yabut of it is if the losses are so great and the cable
long enough it will eventually self terminate. At that point its
not useful to do a SOL cal at the far end as the reflections are
absorbed before they reach the instrument.

Allison
-----------------
No direct email, it goes to bit bucket due address harvesting in groups.IO

On Tue, 19 May 2020 at 22:36, pez@arg <petrosez7@...> wrote:

| On Tue, May 19, 2020 at 09:48 PM, <sj@...> wrote:
=
|
| I would say NO.
| Sorry to say, but have worked with VNA's for 30 years and as soon as you
come
| near 1/8 wavelength the measurement errors are taking over.
| You know, in the analyzer the matrices that are multiplied together, the
error
I matrice will start to influence significantly. It is very difficult to
say
| that it always will not work when exceeding 1/8 (because you are closing
in to
| 1/4 and the matrice in play will get 0's and infinite in some places)
because
| let's consider you are clever and you measure in a narrow sweep where
your
| cable length is not any close to a 1/4 wave multiplum, then it can
actually
| work to some extend.
|
| Generally if you can't evaluate when you are measuring correct, I
recommend
| you to keep your calibration point as close as possible to the analyzer
and
| respect you might have significant errors if your CAL point exceeding
1/8 wave
| length away from the port.
|
| People believing they can calibrate out 20 meter of coax at any
frequency,
| does not have any idea what they are talking about.

The standard Agilent cables for my HP 8720D VNA are 24" long, which is
about 600 mm. The maximum frequency of the VNA is 20 GHz, so a wavelength
of approximately 15 mm. Even ignoring the velocity factor of the cables,
that makes them 40 wavelengths long.

Maybe you mean something different to what I think you mean.

Dave

Thank you. I see it now. My old eyes need some magnification hi... hi

Tony VE3DWI.

On Tue, May 19, 2020 at 20:59 Roger Need via groups.io <sailtamarack=
[email protected]> wrote:

On Tue, May 19, 2020 at 05:11 PM, Tony wrote:

Why are the two measurements not taken in the same display format? One
graph is in SWR one is in RL.

Tony VE3DWI.

They are all taken in the same format! All 4 graphs have both
measurements on them. The results are so close that one is directly
overlaid on the other and you can't tell one from the other except at a few
frequencies. Take a close look at this plot - I zoomed in to show the 2
plots.

Roger

On Tue, May 19, 2020 at 05:11 PM, Tony wrote:

Why are the two measurements not taken in the same display format? One
graph is in SWR one is in RL.

Tony VE3DWI.

They are all taken in the same format! All 4 graphs have both measurements on them. The results are so close that one is directly overlaid on the other and you can't tell one from the other except at a few frequencies. Take a close look at this plot - I zoomed in to show the 2 plots.

Roger

I got a set from Amazon for like $15 US. 2 so239 and 2 pl259

Why are the two measurements not taken in the same display format? One
graph is in SWR one is in RL.

Tony VE3DWI.

On Tue, May 19, 2020 at 17:24 Roger Need via groups.io <sailtamarack=
[email protected]> wrote:

On Tue, May 19, 2020 at 12:48 PM, <sj@...> wrote:

I would say NO.
Sorry to say, but have worked with VNA's for 30 years and as soon as you

come

near 1/8 wavelength the measurement errors are taking over.

I respectfully disagree. My NanoVNA was calibrated from 2 to 50 MHz using
NanoVNA Saver. Then I measured a 20M dipole at the feedpoint and saved the
results as an S1P file . I added 55 feet of RG58 to the NanoVNA and
re-calibrated at the end of the 55 feet of coax. Connected the antenna to
the RG58 and saved the results. Then plotted in NanoVNA Saver using both
sweeps (one as the reference). The results are in the pdf file below. It
is almost a perfect overlay of the two sweep measurements so the 55 feet
was successfully calibrated out.

Roger

Thanks Roger!

Here is a photo of a Hugen 3.4. looks the same as Jason's

Close up of the other one

Close up of white one.

Jason,

It could be a genuine Hugen 3.4. Hugen posted that he does sell them with "sandwich" type construction instead of in a plastic case with the gift box.

Roger

Captured in the wild. I am aware the white one is an inferior clone but the black one appears to have a newer pcb and has a version 3.4 screened on the pcb. Is this a genuine one? It has a different board layout that brings uart p3 contacts to the edge along with p1 (dfu) and p2.

Thanks,
Jason

| On Tue, May 19, 2020 at 09:48 PM, <sj@...> wrote:
=
|
| I would say NO.
| Sorry to say, but have worked with VNA's for 30 years and as soon as you come
| near 1/8 wavelength the measurement errors are taking over.
| You know, in the analyzer the matrices that are multiplied together, the error
I matrice will start to influence significantly. It is very difficult to say
| that it always will not work when exceeding 1/8 (because you are closing in to
| 1/4 and the matrice in play will get 0's and infinite in some places) because
| let's consider you are clever and you measure in a narrow sweep where your
| cable length is not any close to a 1/4 wave multiplum, then it can actually
| work to some extend.
|
| Generally if you can't evaluate when you are measuring correct, I recommend
| you to keep your calibration point as close as possible to the analyzer and
| respect you might have significant errors if your CAL point exceeding 1/8 wave
| length away from the port.
|
| People believing they can calibrate out 20 meter of coax at any frequency,
| does not have any idea what they are talking about.
=
+1

Here is a file containing the R+jX comparison from the experiment above. Sweep at feedpoint and at end of 55 feet of RG58 overlay on top of each other.

Roger

On Tue, May 19, 2020 at 12:48 PM, <sj@...> wrote:

I would say NO.
Sorry to say, but have worked with VNA's for 30 years and as soon as you come
near 1/8 wavelength the measurement errors are taking over.

I respectfully disagree. My NanoVNA was calibrated from 2 to 50 MHz using NanoVNA Saver. Then I measured a 20M dipole at the feedpoint and saved the results as an S1P file . I added 55 feet of RG58 to the NanoVNA and re-calibrated at the end of the 55 feet of coax. Connected the antenna to the RG58 and saved the results. Then plotted in NanoVNA Saver using both sweeps (one as the reference). The results are in the pdf file below. It is almost a perfect overlay of the two sweep measurements so the 55 feet was successfully calibrated out.

Roger

We have a couple of small dealers selling them.

Yes, intended to put "(small screen)" after SAA ...