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Hi DiSlord,

Flashed your latest firmware 0.8.4.4, no problems sofar. Please find attached my results measuring the 50 Ohms standard , 50 Ohms standard paralleled by 50 Ohms and CH1, after calibration.

After flashing, the threshold setting still was 300900000, my setting before the? flashing.

Best regards

Jos

There must be something else as I cannot reproduce your results.
Now, I am using a NanoVNA-F, but I can't see where that matters.
Trying to measure a 10 mH RF Choke, display bounces around from
190pH to 600pH.

Guess it's back to my LCR Meter, at least I can get that to work.

Tnx for the reply,

73, Dick, W1KSZ
________________________________
From: [email protected] <[email protected]> on behalf of hwalker <herbwalker2476@...>
Sent: Sunday, April 26, 2020 10:34 AM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] [Measuring] What is your favourite method of measuring inductance in a coil?

Dick 9:58am #12913
What settings did you use to get these measurements ?
=====================================
Dick,
No special settings. Just turned off the CH1 traces, set the frequency sweep from 50k - 1M, and read the inductance on CH0 from the smith chart readout as shown in the screenshot.

- Herb

Dick 9:58am #12913
What settings did you use to get these measurements ?
=====================================
Dick,
No special settings. Just turned off the CH1 traces, set the frequency sweep from 50k - 1M, and read the inductance on CH0 from the smith chart readout as shown in the screenshot.

- Herb

What settings did you use to get these measurements ?

Tnx, Dick, W1KSZ
________________________________
From: [email protected] <[email protected]> on behalf of hwalker <herbwalker2476@...>
Sent: Sunday, April 26, 2020 8:33 AM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] [Measuring] What is your favourite method of measuring inductance in a coil?

Luis,
Most commercial LCR meters for less than $200 only measure inductance or capacitance below 1 MHz. Manufacturers specify the values of their inductors or capacitors at a specific test frequency, also usually below 1 MHz. The NanoVNA can give measurements to at least 5% for inductors and capacitors using fairly simple fixtures such as the sma-banana plug adapter in the attached photos.

The attachments shows a Cambion 22 uH inductor being measured. From 50 kHz - 1 MHz the measured values vary from 22 uH by 0.5 uH.

If you attempt to measure the inductance or capacitance of the components at higher frequencies then the lead length, self-resonant frequency, and fixture all start to come into play with your measurements.

- Herb

Luis,
Most commercial LCR meters for less than $200 only measure inductance or capacitance below 1 MHz. Manufacturers specify the values of their inductors or capacitors at a specific test frequency, also usually below 1 MHz. The NanoVNA can give measurements to at least 5% for inductors and capacitors using fairly simple fixtures such as the sma-banana plug adapter in the attached photos.

The attachments shows a Cambion 22 uH inductor being measured. From 50 kHz - 1 MHz the measured values vary from 22 uH by 0.5 uH.

If you attempt to measure the inductance or capacitance of the components at higher frequencies then the lead length, self-resonant frequency, and fixture all start to come into play with your measurements.

- Herb

I use XJW01 digital bridge 0.3% for measure R, L, C

Measure C: 0,1 pF–10000 mF
Measure L: 0,01 uH–1000 H
Measure R: 0,0002 Ом–9,999 МОм

If calibrate on good calibration standarts allow get better result

Use for measure 4 wire line

It show very good result

Hello team,

Trying to understand a good method of measuring the inductance - lets say around 110uH - of a coil.

Is the L/C method the best? Is there any direct method of measuring the L?

Also, for L/C circuit where can I find a 1% accurate capacitor around 50 or 100 pf? If this LC method is the best, then I will make a jig where the capacitor its already embedded and I only add the coil.

Cheers!


Luis CT2FZI

You don't need to add a switch, just use the same jumper as I used which is the method the H4 uses and you only need to hold down the jog switch when turning on the Nano.?
/g/nanovna-users/message/10026





On Sun, 26 Apr 2020 at 5:01 AM, Aleksander Shalygin<shalygin@...> wrote: Did so. It has become convenient to enter programming mode.

Hugen! Go ahead!
Design on max2870, adf 4355

Did so. It has become convenient to enter programming mode.

The earlier comments about mismatch and cable length are probably correct. You said you checked the SWR at the connection to the transmitter and it was correct. Now take the MFJ out of the circuit and use the NanoVNA to check the antenna SWR at that connector to see what it reads. Depending on the actual SWR at the ANTENNA, you can get radically different results at 2M from just a few inches of added cable length.

Once upon a time I was installing a quarter-wave whip on my car. Just installed the mount, ran the coax, and put a connector on the cable. I could NOT get a whip to work in the 2M band! I tried about 6-8 different whips ranging from 132MHz to 174MHz, and they all read fine as predicted by length, except the whips cut for the 2M band. I eventually cut 6" off the coax, installed a new connector, and all the whips read as they should. I just happened to have a cable length that was a resonant length around 145-148MHz and no antenna would give a good SWR in that range.

If you want to understand the problem, check the Handbook or search the web for explanation of how to use quarter-wave matching sections in antenna systems. Or just read some articles about using quarter-wave coaxial stubs.

If you want to SEE the problem with your NanoVNA, connect the two SMA cables to the VNA and join the far ends with a SMA Tee connector. This is effectively what you have when you to the "Thru" calibration of the VNA so the result should be a flat line in your mode of choice. Then find a short stub of coax with a connector on one end and noting on the other end of the coax. Attach that to the Tee and check the return loss or SWR sweep on the VNA. At the frequencies where the cable has a resonance you will see dips or peaks on the screen.

You may have trouble seeing it on the VNA at max bandwidth because it only has 101 test points, but if you narrow down the frequency range to maybe 150-200MHz with a coax stub length around 12-14 inches, I'm guessing you will see a disturbance in the display when you connect the cable. The actual frequency depends on the cable length and velocity factor of the coax, so I can't guess any closer what the frequency will be with your coax stub. For extra credit, short the end of the coax with a pin or short wire and see what happens. Look it up in the previously mentioned articles to find out why that happened. :-)

73, Doug, N0NAS.

I am not the best source for info regarding duplexor tuning but I have done over 30 of them for hams in my local area. I'm not really aware of ANY of the cheap spectrum analyzer-tracking generator boards that can really do the work to get below 70-80dB rejection, just as others have said. Many duplexors are good enough that even good commercial equipment has trouble getting down to the bottom of the notch.

If you want some good direction and explanation of the process, YouTube is your friend. I've found some excellent duplexor tuning videos out there. Don't stop with the first one, watch a bunch of them to get all the tips and tricks, and also to help filter out the poor videos. And most of the major duplexor manufacturers have some very well written documentation to explain how to tune their equipment. The general steps are all the same, but details can vary.

Regarding that last 20-30dB of tuning, the further down you can tune with the NanoVNA or other hardware, the better off you are. Tune the notch as good as you can and as symmetrically as you can. I've used my DG8SAQ VNWA3 to tune duplexors before. When I get the notch tuned as well as possible, I used to disconnect the signal source from the duplexor and replace it with a HT set on low power. That gets me an extra 20-30dB of signal and I can tune the notch deeper. You should also put a 6dB pad between the HT and duplexor to make sure the input impedance is still near 50 ohms.

TWO WARNINGS about this method.... It is extremely easy to blow the VNA using this method. Don't blame me if it happens to you!

First, don't adjust anything very far from the notch center since the signal reaching the VNA can rise quickly and let the smoke out... If the duplexor adjustments are "touchy" you might not want to try this. (You probably should do some maintenance first....)

Second, not all HT radios are created equally... Some have a LOT of spurs, and some don't properly kill the TX when the VCO isn't locked. I blew up my VNWA3 when I keyed my VX1 HT and it swept in to operating frequency while transmitting at full power. Just a few 100mw, but it went well outside the duplexor notch and sent that RF to the VNWA3 mixer. It took it a few times before theVNWA lost about 40dB of sensitivity. After it blew, I tested the VX1 over a wider frequency range and could see the signal as it swept in to phase lock. So be careful!

For a less dangerous option, just remember that the NanoNVA is listed as -13dBm output. Most commercial signal generators will go to at least +20dBm output. That gets you an extra 30dB of notch depth from a stable and clean signal source. But you need to be REALLY careful with your connections and frequency changes. Don't screw up!

73, Doug, N0NAS.

Latest version reintroduces 300MHz threshold crossover anomaly. I did not attempt to correct thru threshold adjustment. Otherwise, seems stable. Calibration and various device tests were successful.

Peter

Good, ok i change 96kHz mode for AIC ADC (now increased external freq), possible it help (on my H4 it also give good result)

Also i change IF to 8kHz (in my test got less noise)
Additional not use float type variable on DSP (float type can lost data) it allow more correct measure low level signal (it only for H4, processor have hardware DSP instruction support)

Need reset old calibration settings

PS made test CH1 port use up to 80dB attenuator, get this measure result (on high freq better use high bandwidth for better result)
-85dB on 1-300MHz
-70dB on 300-900MHz
-50dB 0n 900-1500MHz
-40dB on 1500-2400MHz
-30dB on 2400-2700MHz

On Sat, Apr 25, 2020 at 12:32 PM, Peter Finch wrote:

... This latest firmware version with reduced DAC sample rate is stable on my H4.

As an aside, there is no harmonic anomaly around 300MHz. Plots are clean with the unchanged threshold setting of 300MHz on tight sweeps of 295-305MHz, 299-301MHz, and 299.99-300.01MHz....
==========================================

Good news! Peter,
Thanks for the feedback. I'm sure finding out about issues like yours is why DiSlord has released his beta versions to this group. Whatever advantages the 96 kHz DAC sample rate may have, if it causes problems on some NanoVNA's then hugen would not want to include it in his final release.

After enjoying the new bandwidth, sweep points, lower start frequency and increased sweep rates I would be broken-hearted if I had to go back to the stock firmware.

- Herb

This latest firmware version with reduced DAC sample rate is stable on my H4.

- I ran it on a short connector for 20 minutes with no error drift over time in the display.
- I was able to successfully calibrate the H4 (using 201 sweep points Woo! Hoo!).
- The displayed plots match previous plots for known DUTs.
- NanoVNASaver no longer reports data out of range errors.

As an aside, there is no harmonic anomaly around 300MHz. Plots are clean with the unchanged threshold setting of 300MHz on tight sweeps of 295-305MHz, 299-301MHz, and 299.99-300.01MHz.

Thank you!

Peter

On Sat, Apr 25, 2020 at 07:38 AM, hwalker wrote:

A hugen distributed 4-inch 3 GHz S-A-A-2, in a case with SOLT standards and
cables for under $100 would create it's own market.

I'd buy one in a heartbeat!

Awesome, I will see if some of the locals are interested.
Thanks

The PCB+partial PCBA would cost around ~$50 for 2pcs, and only slightly

On Sat, Apr 25, 2020 at 09:11 AM, Gabriel Tenma White wrote:

Right now my biggest task on the firmware is adding moonrunes support which a lot of their domestic users are asking for.
======================================

Thanks for clarifying Gabriel. I had to look up "moonrunes" as I'm not familiar with the term. Am I correct in believing that it is to add Japanese characters as a language option?

- Herb

A little note. The response of such very sensitive devices can be

expected to shift a little when connected in the field. The bench tuning
is a start. The tuning is completed up at the site by tweaking when all
connections have been made.

+++++


On 2020-04-25 8:12 a.m., Lawrence Macionski via groups.io wrote:

I am not the 1st to respond, but I have used my NanoVNA to tune a 6 cavity Waco VHF and a 4 cavity, "Cigar tube" UHF duplexer (Ritron). Regarding notches When you approach 70db attenuation, the graph gets "noisy".. With a NanoVNA use at least 2 passes per 1Mhz. It's slow but seems to get the job done. Since you can not resolve -90-100dB with the NanoVNA. I opted to "imagine" the dip to continue below a smoothe line in the area of the noisy bottom.
I used a marker on my desired frequencies and tuned so that the marker was midway between the noisy area of the notch.. I hope I am expressing the theory that the "dip" is symmetrical, and "down in the noise". Having the marker frequency set mid-way in the noisy area should "guesstimate" the lowest point of the notch. I did save a snapshot of my start as you can see the notch area is off. The markers are 144.67-145.27...Ideally you want the marker in the middle of the notch noisy area..Not everyone is rich nor has access to expensive commercial test gear. 40 years ago I watched a guy tune duplexers with an 10 watt transmitter, a receiver. a VTVM, 140 feet of RG-58 coax and a step attenuator. He made the duplexers out of old soda water fire extinguishers.

--

John

at radio station VE7AOV