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I finally started learning about this thing and all the videos I've seen so far show four traces. I've only got two. Do I need a firmware update, or what?

Excellent work Martin! Many thanks for your efforts in producing this great
reference.
73, Don W5MML ?

I have used the full Adobe Acrobat, Adobe Acrobat Reader and a program
called PDF24 to open it. It opens fine with all three for me.

Zack

On Wed, Jan 27, 2021 at 4:12 PM G8DQX list <list@...> wrote:

Arnold,

it's an apparently straightforward PDF 1.3 file. It should be readable
by most PDF-capable readers. Sounds like a secondary issue, such as an
over anxious protection mechanism somewhere.

HTH, 73, Stay Safe,

Robin, G8DQX

On 27/01/2021 21:29, arnold slag wrote:

Ik cant open the file:-(

73 Arnold pe1owg

<>
Virus-free.
www.avg.com
<>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

Arnold,

it's an apparently straightforward PDF 1.3 file. It should be readable by most PDF-capable readers. Sounds like a secondary issue, such as an over anxious protection mechanism somewhere.

HTH, 73, Stay Safe,

Robin, G8DQX

Ik cant open the file :-(

73 Arnold pe1owg

Op wo 27 jan. 2021 19:40 schreef Larry Rothman <nlroth@...>:

I have found that using regular magnet wire with teflon tubing slid over
the wire will easily handle 2KW. I have wound a number of 4:1 transformers
as well as 49:1 transformers for EFHW using this method. All the balun
designs use a similar scheme; most likely due to the cost and difficulty in
obtaining silvered wire.

Ken WB6MMV

On Wed, Jan 27, 2021 at 2:10 PM David Eckhardt <davearea51a@...>
wrote:

I was also surprised it broke down, but every CMC I wound with solid #12
enameled wire broke down between 400 and 700 watts. I believe it has a lot
to do with the impedances in which the CMCs are installed. My W/C is on
40-meters where I measure 1161 - j1110 at 7.0 MHz. My lowest impedance is
at 2.0 MHz and measures 19 - j288.

I have not tried or thought of using teflon coated silvered conductor. I
need to find it and, if not too expensive, give it a try.

I rewound the 400-31 single core with the DavisRF 'antenna' wire with no
problems to at least 1.2 kW. It is certainly better at CM impedance than
the 43 material especially on 160 and 75 meters but 43 is a bit better on
the higher bands - as expected.

Out of all the CMCs I've wound and tested, I have three that I can use, all
wound with the DavisRF #14 stranded and insulated antenna wire: 1)
240-31, 15 turns, 2) 300-43, 16 turns, and 3) 400-31, 21 turns. Those
remaining do not perform well under DM loss (rejection) or phase balance
(π-radians out of phase) and/or amplitude balance on the DM side. I'm
going shopping for Teflon coated silvered solid conductor.

Dave - W?LEV

On Tue, Jan 26, 2021 at 11:26 PM Jim Lux <jim@...> wrote:

On 1/26/21 3:04 PM, n2msqrp wrote:

Dave,

Have you tried teflon covered silver plated wire?

Mike N2MS

The silver doesn't help much for RF conductivity, but it is a LOT easier
to solder to.

I'm kind of surprised that magnet wire broke down. Most magnet wire is
good for a kilovolt or so, because motors and transformers get hi-pot
tested at 2-5kV.

Decent insulated magnet wire



Catalog here:


AWG 12 copper bare is 0.0808 (nom)

single build is 0.0825 (i.e. the insulation is 8.5 mils (0.2 mm) thick

heavy build is 0.0842 is twice as thick. (0.4mm)


most plastics have breakdown strength of 20 kV/mm or more, especially
for thin layers.

PTFE (Teflon) and Polyimide (Kapton) are a lot better (100 kV/mm)

Polyester (Mylar) is in between (50kV/mm)

Note that thinner layers have a higher breakdown voltage per mm (that
is, you might find that a layer that's 0.1 mm and 1mm have almost the
same breakdown voltage)

Formvar is about 11kV as typically applied to wire.

On 01/26/2021 3:30 PM David Eckhardt <davearea51a@...> wrote:


Those wound with the #12 enameled solid conductor do not take power

with

my ant/feedline impedances resulting in discharges between bifilar

pairs

(not between individual bifilar windings). Also, the green wire of
unknown insulation does not take power. So, those CMCs wound with

solid

conductor are coming apart and being rewound in some fashion or

another

with the DavisRF "antenna" wire which seems to take power to at least

1.2

kW. Your mileage may vary with different impedances presented to the
chokes.

Those frequencies on which I tried the CMCs at power are:
3.8 MHz 24 - j56
7.15 MHz 493 - j740
Impedances noted are measured at the shack end of the parallel wire
feedline.

Dave

--
*Dave - W?LEV*
*Just Let Darwin Work*

I was also surprised it broke down, but every CMC I wound with solid #12
enameled wire broke down between 400 and 700 watts. I believe it has a lot
to do with the impedances in which the CMCs are installed. My W/C is on
40-meters where I measure 1161 - j1110 at 7.0 MHz. My lowest impedance is
at 2.0 MHz and measures 19 - j288.

I have not tried or thought of using teflon coated silvered conductor. I
need to find it and, if not too expensive, give it a try.

I rewound the 400-31 single core with the DavisRF 'antenna' wire with no
problems to at least 1.2 kW. It is certainly better at CM impedance than
the 43 material especially on 160 and 75 meters but 43 is a bit better on
the higher bands - as expected.

Out of all the CMCs I've wound and tested, I have three that I can use, all
wound with the DavisRF #14 stranded and insulated antenna wire: 1)
240-31, 15 turns, 2) 300-43, 16 turns, and 3) 400-31, 21 turns. Those
remaining do not perform well under DM loss (rejection) or phase balance
(π-radians out of phase) and/or amplitude balance on the DM side. I'm
going shopping for Teflon coated silvered solid conductor.

Dave - W?LEV

--
*Dave - W?LEV*
*Just Let Darwin Work*

Generally, a few clamp-on ferrites of the appropriate material at the
feedlint is all you really need. In that respect, even those ferrites
aimed at EMC and RFI control are good for that purpose at VHF/UHF
frequencies. The first KLM 2-meter beam I had I some 40 years ago I built
and installed a 1/4-wavelength 'bazooka' balun. It worked fine, but the
clamp-on ferrites are a whole bunch easier to install. On 70 cm I have
used the 1/2-wavelength coaxial 4:1 balun. The subject is treated in any
good reference addressing antennas and transmission lines at VHF,UHF.

Dave - W?LEV

On Wed, Jan 27, 2021 at 5:13 PM John Button G8JMB via groups.io
<hornpipe112@...> wrote:

CMC-VHF-UHF

Has anyone done any work on VHF/UHF CMCs. power level 25W or so, rather
than megawatt monster HF CMCs?

There seems to be a lack of info on such items and on realistic power
level [ie, 100W] HF CMC

73
John G8JMB

--
*Dave - W?LEV*
*Just Let Darwin Work*

Hi, Dave
Maybe QRZ doesn't like the docx format. Here's a PDF version for you to try uploading.
This also cuts the file size down from 506K to about 70K.
Mike K1YUP

On Wed, Jan 27, 2021 at 06:43 AM, dsay2001 wrote:

I've had my H4 for a while now, and I really like it.

I've been trying to get an idea of its SWR accuracy, so I compared it to a
friend's RigXpert.
I wrote an app that reads the RigXpert's AntennaScope files and
NanoVNAServer's Touchstone files, and plots the SWR of each.
The results are not what I expected - pretty different (image attached,
RigXpert-NanoVNA-Comparison.png). I didn't expect the results to match
exactly, but I thought they would be close.

I've looked over a number of posts here, and haven't really found an answer. I
hope these points answer some of the issues I've seen raised for similar
questions:
- Both source files have 101 datapoints.
- The SWR plots I generate match the plots I see in the AntennaScope and
NanoVNASaver software.
- I connect the cable from the antenna directly to the RigXpert, and for the
Nano, I add a 12" SMA-SO239 adapter cable.
- I calibrate the Nano for 144-148 MHz, Open/Short/50 ohm.
- NanoVNAServer v0.3.4
- The H4 version info is in an attached image (NanoVNA-H4-Version.png).

It's certainly possible that the RigXpert is wrong, but that seems like a low
probability.
I see there is a newer firmware version, but it seems to be lacking release
notes. Will that solve the problem?

I own a RigExpert and a NanoVNA-H4. The results are almost identical when I make measurements if I do things correctly.

I think your problem is that you have a common mode issue on your antenna system. If you do not have a proper balun, unun or RF choke at the antenna feedpoint the outer surface of the coax shield will form part of the antenna. Anytime you change the length of the coax or how it is grounded at the radio end you are effectively changing the antenna feedpoint impedance and will get slightly different SWR measurements. For VHF this is very common with antennas like a dipole, J-pole or a whip.

Here is a simple test to see if this is the case. Measure the antenna with the RigExpert in stand-alone mode and then use the Save feature to store the results on the RigExpert analyzer. Then connect it to your computer with a USB cable, measure again and save these results in another file on the Rigexpert. Then start AntScope 2 and connect to the RigExpert. You can import both files into AntScope2 (bottom right corner of AntScope2). These are RigExpert files not Touchstone. Both will plot on the screen and you can see if there is any difference. Now save both files on your PC. Exit AntScope.

Next step is to disconnect the RigExpert from the antenna and POC. Calibrate your NanoVNA for the desired frequency range and connect to the antenna with your pigtail. Connect it to the PC and start AntScope2. Go into settings and you will see an option to connect to your NanoVNA (latest AntScope2 supports the -H4). Connect and then exit settings and do a sweep. It will now plot on the screen. You can now import the 2 files you saved earlier and compare all 4 measurements. I suspect only two will closely match and the standalone RigExpert will be different.

Roger

Paul, It's a pdf file - you can print your own individual pages using Adobe Reader

I really appreciate what you are doing. I have printed v1.5 and now I
wonder if there is a possibility of just printing certain pages of v1.6 to
replace same.

At the same time I don't want to be asking an unreasonable request.

Paul W8SBH

On Tue, Jan 26, 2021, 3:10 PM [email protected] Notification <
[email protected]> wrote:

The following files have been uploaded to the Files area of the
[email protected] group.

- /Absolute Beginner Guide to The
NanoVNA/Absolute_Beginner_Guide_NanoVNA_v1_6.pdf
</g/nanovna-users/files/Absolute%20Beginner%20Guide%20to%20The%20NanoVNA/Absolute_Beginner_Guide_NanoVNA_v1_6.pdf>

*By:* Martin J.K.

*Description:*
New in version 1.6: - expanded firmware upgrade and the driver
installation section - some typo errors corrected. Thanks to everyone who
points me to typos and email good suggestions for improvement.

CMC-VHF-UHF

Has anyone done any work on VHF/UHF CMCs. power level 25W or so, rather than megawatt monster HF CMCs?

There seems to be a lack of info on such items and on realistic power level [ie, 100W] HF CMC

73
John G8JMB

The Balun Designs bifilar-wound choke-baluns use #16 or #14 (not sure) bare wire slid into very small Teflon tubing. (I think Amidon has it).
I use the 1171, rated at 5kw and 10kv - - with T-network and ladder line.
Good pictures, graphs, and specs on that site.
73, --kv5r
PS: no connection to them, just a customer.

Get a known standard, whatever that may be, a load standard, a short
section of characterised coax etc and compare the results.
What you are doing now is if I gave you an unknown weight and you measured
it on 2 bathroom scales.

On 1/26/21 8:29 PM, dsay2001 wrote:

I've had my H4 for a while now, and I really like it.

I've been trying to get an idea of its SWR accuracy, so I compared it to a friend's RigXpert.
I wrote an app that reads the RigXpert's AntennaScope files and NanoVNAServer's Touchstone files, and plots the SWR of each.
The results are not what I expected - pretty different (image attached, RigXpert-NanoVNA-Comparison.png). I didn't expect the results to match exactly, but I thought they would be close.

I've looked over a number of posts here, and haven't really found an answer. I hope these points answer some of the issues I've seen raised for similar questions:
- Both source files have 101 datapoints.
- The SWR plots I generate match the plots I see in the AntennaScope and NanoVNASaver software.
- I connect the cable from the antenna directly to the RigXpert, and for the Nano, I add a 12" SMA-SO239 adapter cable.
- I calibrate the Nano for 144-148 MHz, Open/Short/50 ohm.
- NanoVNAServer v0.3.4
- The H4 version info is in an attached image (NanoVNA-H4-Version.png).

It's certainly possible that the RigXpert is wrong, but that seems like a low probability.
I see there is a newer firmware version, but it seems to be lacking release notes. Will that solve the problem?

Thanks for any insight.

73,
Don Sayler W7OXR

My first thought would be that there is some "fixturing" issue - that is, if you're connecting the VNA/Scope at the antenna, the analyzer is part of the circuit.


You need to isolate the antenna being measured from the measurement system (and you) -? if the antenna is 100 feet away, and there's 100 ft of coax between you and the antenna, or if you make a metal covered box on which the antenna is mounted, and your analyzer is in the box.


What I would do to compare is to build a test load that is a RLC resonant at 144 MHz (or there abouts) with the right R to get the resonant impedance approximately right.? Probably one of the easiest ways is to cut 1/2 wavelength of coax, short the far end, and put a 50 ohm series resistor.? it will be 50 ohms at resonance (because the coax will look like a short) with SWR 1:1, and gradually worse on either side.

Run that on both analyzers and see how well they match.

Any member can add to the wiki - go wild.....

Don,

Have you checked the velocity factor settings on the rig expert?

Was your pc isolated from earth, ie a laptop. I've heard that an earthed computer connection has quite an effect.

Just a couple of suggestions.

Wes G7CHO

Dear All,

I am new to Nanovna. I need to connect the nanovna using teraterm (or
similar)to be able to communicate with the device. I am unable to get the
prompt on the terminal even with the appropriate settings (i.e. buad rate,
stop and parity etc.). The nanovna windows software (vna qt) is working
properly over the same port however, not for serial terminal.
A reply would be really helpful!

Best Regards
Adnan

This post #19816 ought to go in the Wiki #19816. Worked for me, but took me ages to search for this answer in the forum.