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max may i suggest unless you are going to answe the original question keep your mouth shut and hands away from the keyboard,seems you can do neither!.

Have you had an email come in from groups.io a week or so later and since there was no quoting you have no clue what the question was really about? Like this one, the subject line says "Correct button? That doesn't tell me anything. But since I'm quoting you, you and everyone else knows exactly what post I referring to.

well , had this question as well but after reading thru this lot,it still doesent to anwer the original question,its harder to understand when ppl quote what been said already in the thread,just makes it a confusing mess to try and read!!.

I just had the same problem a couple of days ago. A web search found a statement that at least some phones with USB-C connectors still need the OTG adapter. I went back to using an older phone with the Micro-USB connector, and an OTG adapter.
I could not get the newer Moto G6 (USB C) to work with the NanoVNA.
--
Doug, K8RFT

Hi all i have an old version H vna,its running hugens 555 firmware,just wondered the max number of save slots it has,just wondered if i can cal it too all the hf and vhf amature bands excert 6+ 4 mtrs?,TIA.

Good morning Barry

super.... unfortunately I have missed the three sessions ,and this is not recorded I would be happy to share your 200 slides and ask questions . I have experiment with VNA an anything related. I am a retired engineer and would welcome to share some of the presentation from university of liege ( this is in Belgium)
I believe this is in English must check.
again this is a super idea, how do we link with soon the conference and what is the difference in time between your location and Belgium ?

de ONL11812 Pierre
Nov 16th

On 11/15/22 12:06 PM, Stan Dye wrote:

And you also need to know that the measurement is not exact: you will only
get within several percent of the cable length at best. This is due to the
way the nanovna (or host software) does the TDR measurement. The nanovna
measures at discrete frequencies using its frequency scan, then the
software takes those points and calculates an FFT to change to the time
domain. This inherently uses a 'bin' size, which limits the granularity of
the measurement. You can see this granularity as you step across the TDR
graph - each calculated point is separated by this minimum granularity.

Rather than TDR - (where the resolution is c/(frequency step size))

I'd suggest just measuring phase at your frequency of interest - You can directly display phase vs frequency, set a marker or two, and go to town.
In any of the PC tools, you can put a reference trace up of one of the cables as you measure and cut the other.

Then you don't have any issues with interpolation between bins in the FFT.

Barry,

I enjoyed your talk yesterday evening ..
Next Monday at 7PM is fine with me…

Should I use the same zoom invite?

Tnx & 73s

Doug KD4NC

Kennesaw, Ga

Yes, open or shorted gives equivalent measurements (one is phase-reversed
from the other).
And terminated in the characteristic impedance of the cable will give an
'infinite' measurement (no reflection).

How to adapt to other cables? You can do other cables the same way, even if
they are balanced or not of 50-ohm impedance. You do need to know the
velocity factor.

And you also need to know that the measurement is not exact: you will only
get within several percent of the cable length at best. This is due to the
way the nanovna (or host software) does the TDR measurement. The nanovna
measures at discrete frequencies using its frequency scan, then the
software takes those points and calculates an FFT to change to the time
domain. This inherently uses a 'bin' size, which limits the granularity of
the measurement. You can see this granularity as you step across the TDR
graph - each calculated point is separated by this minimum granularity.

If your vna firmware has the "Measure / Cable" option in the menu, it is
better to use if you want to find the length of the cable (or the distance
to a break, if you have seen one in the TDR). It still is only as accurate
as your estimate of the cable velocity factor, but is accurately measured
(it uses a different technique without any binning effect/uncertainty).
The Measure Cable function will also show the characteristic impedance of
the cable, and the loss in dB along the length of the cable.

Some very important observations in previous responses:
1 - to phase match, you don't need any particular value, just to make them
the same for two cables
2 - at your target frequency, 5 degrees is about 1/10 of an inch, a very
exacting measurement over 20 feet of cable: just stress in the cable or
connector issues could easily change its electrical length by that much.
And the velocity factor variability in the cables could readily introduce
that much uncertainty.
3 - you do want to leave the far end of the cable open when using the
nanovna for measurements

Another important measurement issue:
The nanovna 'tdr' measurements can't measure within 0.1 inch at 20 feet.
This is because it is not a true TDR - it uses frequency scanning at
discrete frequency points, then an FFT to compute the corresponding
length. The 'bin' size of the FFT depends on the size of the frequency
scan steps (with an inverse relationship). In TDR mode you can see this as
you move the cursor across the display. The 'length' measurement will be
in steps of so many mm or cm. That is the finest granularity that the TDR
can do for the given frequency range. You can make it more accurate by
expanding the frequency span - but only to a point

One way to deal with this in your situation is to measure one cable,
trimming it by about 1/10 inch at a time just until the nanovna measurement
pops from one 'bin' to the next - meaning you are measuring at the edge of
that bin. Then do the same with the other cable, and you should be very
close. (Assuming there are not significant velocity factor differences in
the two lengths of cable).

Another perhaps better way is to not use the TDR mode, but (if your
firmware has it) the Measure / Cable function. Leave the cable open at the
end. Set the top frequency of the vna such that the smith chart trace is
just over a half-circle. Then note the length of the cable shown. Trim
the other cable to show that same length. You can ignore the velocity
factor and whether or not the length is correct to measured length, since
you only need them to match electrically. This method is usually more
accurate, because it measures the quarter-wavelength resonance of the cable
by finding the phase crossing, using excellent interpolation between
measured frequency points.

Good luck.

Stan

I installed the NanoVna App on my Android hoping to use it on my phone. My phone has a micro usb C socket with usb cable and I normally use this cable to connect to my PC to run NanoVNASave. I bought an micro OTG cable the connects the phone to a usb C socket. I then connect this to the NanoVna using the same cable USB C cable that I have been using before. When I ran the App and tried to connect to the NanoVNA, it says no device found. Anyone had this problem before?

On 11/15/22 10:56 AM, dalerheaume via groups.io wrote:

Sorry...S11 delay. Cable terminated at one end only to allow for trimming.

Probably want end "open" so you get a reflection to measure the length, not terminated in 50 ohms.

On Tue, Nov 15, 2022 at 12:50 PM, Jim Lux wrote:

You're seeing the round trip time of ~50 ns

What does the S21 measure, phase wise?

Rather than fool with TDR.. (or are you using TDR to measure the
distance to the cut end, before installing the connector?)

You can also measure S11 phase at your frequency of interest, it's twice
the one way phase.

at 1.1 GHz, roughly 1 ns per cycle, or ~8" for 360 degrees.
If you want 5 degrees, that's about 1/10th of an inch.

Are your cables at the same temperature? Do they have any other
mechanical variations (many cables "off the reel" have periodic
variations in dimensions).

THANK YOU! That helps tremendously.

Sorry...S11 delay. Cable terminated at one end only to allow for trimming.

The time didn't work the first time, and nothing has changed so it won't work again.

Steve
W5RRX
Las Cruces, NM

On 11/15/22 9:59 AM, Siegfried Jackstien wrote:

I think you got it correct (almost)... But you see a double delay cause its up and back down the cable... 26.8x2=53.6...
And... You need them the same length / delay... If both are 52..or 53 does not matter but they need to be the same.. Right?!
So... Cut the longer a tiny bit shorter... And you have it...
Dg9bfc sigi

They also make cool little length adjusters, at least in SMA. I've not seen one in N or UHF.

They're not cheap, at least new, but they might show up surplus.

Someone with a big box of adapters might also find barrels and other adapters that differ in length by a few mm, which can be useful for phase trimming at microwave frequencies.

I think you got it correct (almost)... But you see a double delay cause its up and back down the cable... 26.8x2=53.6...
And... You need them the same length / delay... If both are 52..or 53 does not matter but they need to be the same.. Right?!
So... Cut the longer a tiny bit shorter... And you have it...
Dg9bfc sigi

Am 15.11.2022 17:21 schrieb "dalerheaume via groups.io" <dalerheaume@...>:

On 11/15/22 8:21 AM, dalerheaume via groups.io wrote:

I am having difficulty constructing a set of phase matched cables using my NanoVNA SAA-2N and the tutorial available at this link .
The cable I am using is Times Microwave LMR-400-LLPX with a nominal length of 20 feet. Manufacturer's specification for time delay is 1.34 nS/ft.
My cables need to be phase matched +/- 5 degrees at 1.1GHz.
The difficulty that I'm having is with the following results returned by the NanoVNA.
Cable 1 measured time delay = 54.35 nS
Cable 2 measured time delay = 52.93 nS
Surprisingly, both values are significantly greater than the calculated delay of 26.8 nS = 1.34 nS/ft x 20 ft
Furthermore, based on the formula in the tutorial, the phase shift appears to be 562 degrees
What am I doing wrong?

You're seeing the round trip time of ~50 ns

What does the S21 measure, phase wise?

Rather than fool with TDR.. (or are you using TDR to measure the distance to the cut end, before installing the connector?)

You can also measure S11 phase at your frequency of interest, it's twice the one way phase.

at 1.1 GHz, roughly 1 ns per cycle, or ~8" for 360 degrees.
If you want 5 degrees, that's about 1/10th of an inch.

Are your cables at the same temperature? Do they have any other mechanical variations (many cables "off the reel" have periodic variations in dimensions).

S11 or S21 delay?

On S11 2x delay (to cable end and back)
On S21 1x delay (from one port to another(

I am having difficulty constructing a set of phase matched cables using my NanoVNA SAA-2N and the tutorial available at this link .

The cable I am using is Times Microwave LMR-400-LLPX with a nominal length of 20 feet. Manufacturer's specification for time delay is 1.34 nS/ft.

My cables need to be phase matched +/- 5 degrees at 1.1GHz.

The difficulty that I'm having is with the following results returned by the NanoVNA.
Cable 1 measured time delay = 54.35 nS
Cable 2 measured time delay = 52.93 nS
Surprisingly, both values are significantly greater than the calculated delay of 26.8 nS = 1.34 nS/ft x 20 ft
Furthermore, based on the formula in the tutorial, the phase shift appears to be 562 degrees

What am I doing wrong?