Re: Just purchased a nanovna. Want to measure SWR.
To test for return loss (which converts to SWR) I test the antenna two ways: As far away from anything metallic or people (I fasten it with velcro in a plastic trash can) and then in the final mounting position. This prevents coupling which affects the response.
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Re: Just purchased a nanovna. Want to measure SWR.
Without a doubt, Pointing at the sky when possible!
Kent
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On Wednesday, April 29, 2020, 7:29:18 AM CDT, Cory <cr.andersen83@...> wrote:
Hi all, first post. I just purchased a Nanovna. I would like to test the SWR of a dual band UHF/VHF coat hanger yagi antenna I made. What would be the best position to have have antenna facing while measuring it? Should it be in an open garage? Outside pointing the sky? In the back of my truck? Does it matter much? Should I move it a little too? Thanks for any advice!
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Re: NanoVNA firmvare, compiled by DiSlord
#firmware
Prepare and upload all code for H to my git
Soon upload H4 code, need prepare it
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Re: Just purchased a nanovna. Want to measure SWR.
I would put it in the position you plan on mounting it.?Sent via the Samsung Galaxy S10, an AT&T 5G Evolution capable smartphone
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-------- Original message --------From: Cory <cr.andersen83@...> Date: 4/29/20 08:29 (GMT-05:00) To: [email protected] Subject: [nanovna-users] Just purchased a nanovna. Want to measure SWR. Hi all, first post. I just purchased a Nanovna. I would like to test the SWR of a dual band UHF/VHF coat hanger yagi antenna I made. What would be the best position to have have antenna facing while measuring it? Should it be in an open garage? Outside pointing the sky? In the back of my truck? Does it matter much? Should I move it a little too? Thanks for any advice!
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look at this: Now, if for some reason your SWR changes with differing
lengths in your coaxial feedline, then you've got common mode RF flowing on
the OUTSIDE of the coax (braid).ax explained hereafter:
73
F6CNG Olivier
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Le jeu. 23 avr. 2020 ¨¤ 23:23, KK4JOW <KK4JOW@...> a ¨¦crit : I have a question I hope you all can help me with. I own a 5 watt ham
radio transceiver and just bought an MFJ-872 Low wattage SWR/Wattmeter. The
reading I get between my radio's internal SWR meter and the MFJ is world's
apart. My rig reads 1.7 when the MFJ reads 3.0. and will also read my power
as more than the power that my radio is capable of putting out. I used the
Nanovna to get an idea if it could help. It reads the same as my internal
meter on my rig both direct from the antenna and through the MFJ SWR meter
without power from the radio. Am I wrong to use the VNA to check the SWRs?
Is there something I need to do with the MFJ meter to match or could that
meter be correct. I hope I'm making sense, I've never had to do this before
even though Ive been a ham for a while now. Thanks for your help!!
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Just purchased a nanovna. Want to measure SWR.
Hi all, first post. I just purchased a Nanovna. I would like to test the SWR of a dual band UHF/VHF coat hanger yagi antenna I made. What would be the best position to have have antenna facing while measuring it? Should it be in an open garage? Outside pointing the sky? In the back of my truck? Does it matter much? Should I move it a little too? Thanks for any advice!
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Thank you very much Roger, that really help!
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Re: NanoVNA firmvare, compiled by DiSlord
#firmware
@DiSlord
Thank you for your fabulous firmware! Great work!
I made the update of my h4 yesterday with clearconfig 1234 first and the flashing the dfu file (Version 0.8.4.4 from your post #12958).
After that I made a 2-port calibration within nanoVNA Saver 0.2.2-1.
The pic shows the calibrated range from 290-320 MHz with a 50 ohms calibration standard on ch0. Great!
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Re: 3.2 inch screen for version2
Hi Herb,
All good?
Thanks for sharing, indeed you are right, bigger characters would take
advantage of the 3.2inch.
Let's see if we will have a AA version as well...
A quarta, 29/04/2020, 03:10, hwalker <herbwalker2476@...> escreveu:
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The 3.2" display I ordered for my S-A-A-2 arrived today (see
attachment). It took all of about 5 minutes to unscrew the old 2.8"
display, remove it from the 14-pin socket and plug the 3.2" display in.
Observations:
1. Visually there is not a big difference between 2.8" and 3.2" display
modules. If the firmware driver for the 3.2" display used hugen's AA
character set, the change would be more worthwhile.
2. The mainboard mounting holes for the 3.2" display module do not line
up with the mounting holes for the 2.8" module, so you have to improvise a
way of securing the 3.2" module to the mainboard, other than the 14-pin
socket. This will be an even bigger problem for a 4" display module since
the module will dwarf the mainboard itself.
3. The 3.2" display module makes a great spare for the original 2.8"
display module and has a SDCard module on the rear which may receive future
firmware support through the 14-pin socket.
- Herb
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Re: Hugen - Are you shipping in new packaging?
Hugen,
Thank you for the clarification.
Roger
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Re: Hugen - Are you shipping in new packaging?
Hello Roger, Since some customers want to DIY their own cases and add larger batteries, we still offer the NanoVNA-H with sandwich construction£¨Just like my earliest handmade ones£©. Out of customer demand for the rev3.4 version, we post the same label on the package as the ABS shell version. If the internal PCB is consistent with what I posted on GitHub, it should be made by us. If the user is not a avid DIYer, I still recommend them to purchase the ABS shell and "gift box" version. The buttons and screen with the ABS shell and "gift box" version are effectively protected and more suitable for daily use.
hugen
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Hugen - Are you shipping in new packaging?
I just saw this posted in the NanoVNA Facebook group. It supposedly is a NanoVNA-H version 3.4. The label looks like a 3.4 version but it is not in the "gift box" with the gold lettering. Seems to be missing a cable and the stylus pick. Is it a genuine Hugen or a copy of his PCB and circuit changes.?
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Re: 3.2 inch screen for version2
The 3.2" display I ordered for my S-A-A-2 arrived today (see attachment). It took all of about 5 minutes to unscrew the old 2.8" display, remove it from the 14-pin socket and plug the 3.2" display in.
Observations:
1. Visually there is not a big difference between 2.8" and 3.2" display modules. If the firmware driver for the 3.2" display used hugen's AA character set, the change would be more worthwhile.
2. The mainboard mounting holes for the 3.2" display module do not line up with the mounting holes for the 2.8" module, so you have to improvise a way of securing the 3.2" module to the mainboard, other than the 14-pin socket. This will be an even bigger problem for a 4" display module since the module will dwarf the mainboard itself.
3. The 3.2" display module makes a great spare for the original 2.8" display module and has a SDCard module on the rear which may receive future firmware support through the 14-pin socket.
- Herb
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The older versions of the NanoVNA-H used a 3.7 V 450 maH battery LiPo battery (602040) and the latest version with the Version 3.4 board uses a 650 maH battery (602540). You can find them on Amazon & eBay and some radio control airplane shops carry them. The connector used is a JST type. Here are some photos..
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The battery size depends on which model you purchased. NanoVna, NanoVNA-H, NanoVNA-H4 or NanoVNA-F.
You can get up and running by plugging a 5V USB power pack into the USB socket on the NanoVNA.
Roger
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I didnt realized that I purchased a NanoVNA without battery :(
What battery can I buy to put on it?
I appreciate the help.
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Re: Testing directional coupler directivity and bandwidth
On Tue, Apr 28, 2020 at 03:24 PM, WB2UAQ wrote:
... I use my Nanonvna with an HP 8721A directional coupler. ...
===============================
The HP 8721A bridge is hard to find on the secondary markets, especially the 50 ohm ones. I've had offers for mine that were hard to resist but I turned down. You should write up an application note for the group on using an external directional coupler to measure return loss and impedance, with accompanying math. I believed one of our members at one time asked Rune if he would add a module to NanoVNA-Saver for measuring return loss and impedance using an external coupler.
- Herb
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Re: Testing directional coupler directivity and bandwidth
I use my Nanonvna with an HP 8721A directional coupler. As noted above attach ch0 to the input of the coupler and ch1 to the reflected port of the coupler. Attach a short to the directional coupler's output port and do a through cal with the short in place. S21 is now the return loss of what is connected to the coupler's output. Because the Nanovna also outputs S21 phase you can calculate the impedance of what is connected to the coupler's output port. The HP 8721A has a directivity spec of 44 dB from 100 kHz or so to 110 MHz. I have verified this with an HP cal kit load. This method might even be more accurate than using Ch0 making an S11 measurement. If you don't have a good commercial coupler, a very good one can be made. All it takes is some wire and a pair of ferrite toroids. Look up the Stockton coupler on the web.
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Re: Testing directional coupler directivity and bandwidth
Thanks all.
Herb, you got me in the right direction I am sur I will be able to figure
this with the link you provided.
<>
Garanti
sans virus. www.avast.com
<>
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
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Le mar. 28 avr. 2020 ¨¤ 13:34, hwalker <herbwalker2476@...> a ¨¦crit : Pierre,
A good illustrated guide for such measurements is at:
Just substitute the NanoVNA CH0 for the signal generator and the NanoVNA
CH1 for the spectrum analyzer in the article. The directivity measurements
will be S21 in dB.
- Herb
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Ernesto Marquez
dekagon
CT2FZI
Roger Need
