Re: Nano VNA 10M Dipole Sweep
Hey David,
? ? Good morning. Everything looks pretty good, and I'm sure you've noted the points about calibrating at the antenna feedpoint.? When transmitting at low power, does your radio / SWR meter indicate pretty much in line with your VNA reading?
10m is a fairly wide band, and if your reading is still inductive, you might try something like inserting a 100pf mica / ceramic cap (at least 500V rating) across the elements at the feedpoint to see if that shifts the impedance / SWR curve more to your liking.?
Congrats on taking the plunge with a DIY antenna, as well as making the effort to see HOW it works...Use common-sense precautions of course to protect your equipment, but remember that if it works, just have fun with it!??
73 de KN7GIG
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On Wednesday, January 15, 2025 at 06:24:49 AM EST, Siegfried Jackstien via groups.io <siegfried.jackstien@...> wrote: at best calibrate at the cable end .... then you see the impedance of the antenna alone ...? not with cable (that may rotate you results in Smith) dg9bfc Sigi Am 15.01.2025 07:23 schrieb "Fran?ois via groups.io" <18471@...>:
I calibrated at the S1 port directly.? Then I connected S1 to the feed line and subsequently
the antenna. The plane I measured would be where the feed line attaches to the radio.
** Yes, I understood what you did.
It is not a mistake. You measure the impedance of your antenna, brought
back by your cable. It is the impedance that your TX sees in transmission.
Where it is a mistake is the deduction of saying that the antenna is too
long. You could, through software like SimNEC, find (see) the calculated
impedance of the other end of the cable (antenna side). But:
- You have to know how to use SimNEC which is not obvious
- Know what you are doing
- Assume that the cable is the one you are using
- Know the exact length of the cable
Add a length of cable (Tx side) and you will see that the impedance
brought back changes
--
F1AMM
Fran?ois
-----Message d'origine-----
De la part de David Gerhart
Envoy¨¦ : mercredi 15 janvier 2025 07:12
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Re: Nano VNA 10M Dipole Sweep
Maybe want to display the SWR
format, as that is probably the easiest to interpret. ** The easiest to interpret: yes But it is not the most relevant. In SWR you display 2 variables; in Smith you display 3. The SWR does not allow to adjust an antenna because, on the Smith, the minimum SWR corresponds to the point closest to the center of the Smith and not to the resonance of the antenna which is the place where the curve intersects the horizontal axis (rective = 0) -- F1AMM Fran?ois -----Message d'origine----- De la part de Tom KG3V Envoy¨¦ : mercredi 15 janvier 2025 01:19
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Re: Nano VNA 10M Dipole Sweep
at best calibrate at the cable end .... then you see the impedance of the antenna alone ...? not with cable (that may rotate you results in Smith)
dg9bfc Sigi
Am 15.01.2025 07:23 schrieb "Fran?ois via groups.io" <18471@...>:
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I calibrated at the S1 port directly.? Then I connected S1 to the feed line and subsequently
the antenna. The plane I measured would be where the feed line attaches to the radio.
** Yes, I understood what you did.
It is not a mistake. You measure the impedance of your antenna, brought
back by your cable. It is the impedance that your TX sees in transmission.
Where it is a mistake is the deduction of saying that the antenna is too
long. You could, through software like SimNEC, find (see) the calculated
impedance of the other end of the cable (antenna side). But:
- You have to know how to use SimNEC which is not obvious
- Know what you are doing
- Assume that the cable is the one you are using
- Know the exact length of the cable
Add a length of cable (Tx side) and you will see that the impedance
brought back changes
--
F1AMM
Fran?ois
-----Message d'origine-----
De la part de David Gerhart
Envoy¨¦ : mercredi 15 janvier 2025 07:12
|
Re: Nano VNA 10M Dipole Sweep
I calibrated at the S1 port directly. Then I connected S1 to the feed line and subsequently
the antenna. The plane I measured would be where the feed line attaches to the radio.
** Yes, I understood what you did. It is not a mistake. You measure the impedance of your antenna, brought back by your cable. It is the impedance that your TX sees in transmission. Where it is a mistake is the deduction of saying that the antenna is too long. You could, through software like SimNEC, find (see) the calculated impedance of the other end of the cable (antenna side). But: - You have to know how to use SimNEC which is not obvious - Know what you are doing - Assume that the cable is the one you are using - Know the exact length of the cable Add a length of cable (Tx side) and you will see that the impedance brought back changes -- F1AMM Fran?ois -----Message d'origine----- De la part de David Gerhart Envoy¨¦ : mercredi 15 janvier 2025 07:12
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Re: Nano VNA 10M Dipole Sweep
Francois,
I calibrated at the S1 port directly. Then I connected S1 to the feed line and subsequently the antenna. The plane I measured would be where the feed line attaches to the radio.
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Re: Nano VNA 10M Dipole Sweep
Hello
Do not lose sight of the fact that the nanoVNA is a kind of measuring bridge that will indicate to you, among other things but above all, the impedance at the point where you did the OSL calibration (open closed load).
If you did this measurement and calibration at the end of the cable connected to your station, it is the impedance of your antenna, brought back by the cable that you see. Do a test by adding a length of cable, without changing the calibration, and you will see that this length of cable rotates the impedance figure on the Smith diagram. However, not all the points rotate by the same angle because the rotation is a function of the ratio between the length of the cable and the wavelength.
If your antenna is easily grounded, you can do your calibration at the connection point of your cable with the antenna, while leaving your NaoVNA at the end of the cable, station side. By replacing the antenna in position, you will measure the real impedance of your antenna. It will be up to you to decide whether or not to integrate the chock balun (if you use one) into the antenna. In any case, your measurement will take into account the parasitic radiation of your transmission line.
Several participants say that your antenna is too long because you are measuring an inductive impedance. As explained above, the line length rotates the impedance on the Smith. It may be that in fact your antenna is too short (capacitive) and that the rotation would make it appear too long (inductive). What is certain is that it is not perfectly adapted. If it were, on the Smith, it would be a point (very theoretical) in the center of the Smith. The cable would rotate this point but since it is in the center, it would not move.
--
F1AMM
Fran?ois
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-----Message d'origine----- De la part de David Gerhart Envoy¨¦ : mercredi 15 janvier 2025 00:55
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Re: Nano VNA 10M Dipole Sweep
You should calibrate as close to the reference plane you are wanting to test as possible. For an antenna that would typically be at the feed point.
73 de Dan AI5OL
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On 1/14/2025 10:08 PM, David Gerhart wrote: Thanks for asking!
"did you calibrate with the coax used? (means short, open, load at the cable end)
I calibrated by attaching the calibrants directly to the Nano VNA H.
"looks like your antenna is a bit on the long side..."
Concur!
i prefer nanovna app on the pc side ... about the fw ... what fw is on your device?? what device do you have??
I'Il search for that app.
The device is a Nano VNA - H2.
-- 73 de Dan AI5OL
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Re: Nano VNA 10M Dipole Sweep
Thanks for asking!
"did you calibrate with the coax used? (means short, open, load at the cable end)
I calibrated by attaching the calibrants directly to the Nano VNA H.
"looks like your antenna is a bit on the long side..."
Concur!
i prefer nanovna app on the pc side ... about the fw ... what fw is on your device?? what device do you have??
I'Il search for that app.
The device is a Nano VNA - H2.
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Re: Nano VNA 10M Dipole Sweep
did you calibrate with the coax used? (means short, open, load at the cable end)
looks like your antenna is a bit on the long side
no need to cut the ends .. just fold them over (cause if you hang it higher you may need that length back) .. and secure with cable tie
i prefer nanovna app on the pc side ... about the fw ... what fw is on your device?? what device do you have??
dg9bfc sigi
Am 15.01.2025 um 00:55 schrieb David Gerhart:
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Fresh out of box. A sweep of my DIY 10M antenna...
S1 - connected to 50' Rg58 via BNC connectors to my 10M dipole. The lowest piece of which is about 12' off of the ground. I set markers a L, M and H points of the band.
S2 port had nothing connected.
The VNA was calibrated just prior to the sweep. An anchored via USB to my Windows tablet.
Now I'm digging into how to read the Smith Chard and return / impedance info...
Comments please!!
Do I need to update VNA firmware or make other changes. Software on the tablet?
What's next folks?
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Re: Nano VNA 10M Dipole Sweep
Looks good. I also just got a nano and have not tried it yet. As a Ham, I am used to looking at VSWR sweep for antennas. It looks like you have not yet found the whole SWR dip, as the lowest SWR is at the lowest point on the sweep. If it were me, I would use that low frequency as the new Center frequency and do another sweep. Maybe want to display the SWR format, as that is probably the easiest to interpret.
Enjoy the new toy,
Tom
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On 1/14/25 18:55, David Gerhart wrote: Fresh out of box. A sweep of my DIY 10M antenna...
S1 - connected to 50' Rg58 via BNC connectors to my 10M dipole. The lowest piece of which is about 12' off of the ground. I set markers a L, M and H points of the band.
S2 port had nothing connected.
The VNA was calibrated just prior to the sweep. An anchored via USB to my Windows tablet.
Now I'm digging into how to read the Smith Chard and return / impedance info...
Comments please!!
Do I need to update VNA firmware or make other changes. Software on the tablet?
What's next folks?
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Re: Nano VNA 10M Dipole Sweep
You don't even have to consult the Smith Chart. The application has done that for you. To the left of the Smith Chart, the application has given you the following information for the three markers you placed: [image: image.png] Marker 1: Impedance = 40.1 + j 15.4 ohms Marker 2: Impedance = 49.4 + j 40.6 ohms Marker 3: Impedance = 99.2 + j 58.2 ohms There's lot's more information, but everything is inductive - plus sign to the complex portion of the impedance. This would indicate the wires are a bit too long. Although the match at the lowest frequency, Marker 1 at 28.300 MHz, is not bad at all and nothing to be concerned about. Still at Marker 2 at 29.000 MHz, not bad. However, the last marker at 29.700 MHz is beginning to show some compromises. The SWR is also given at the top of the second column for each marker frequency. Dave - W?LEV On Wed, Jan 15, 2025 at 12:00?AM David Gerhart via groups.io <DAVID= [email protected]> wrote: Fresh out of box. A sweep of my DIY 10M antenna...
S1 - connected to 50' Rg58 via BNC connectors to my 10M dipole. The lowest
piece of which is about 12' off of the ground. I set markers a L, M and H
points of the band.
S2 port had nothing connected.
The VNA was calibrated just prior to the sweep. An anchored via USB to my
Windows tablet.
Now I'm digging into how to read the Smith Chard and return / impedance
info...
Comments please!!
Do I need to update VNA firmware or make other changes. Software on the
tablet?
What's next folks?
-- *Dave - W?LEV* -- Dave - W?LEV
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Nano VNA 10M Dipole Sweep
Fresh out of box. A sweep of my DIY 10M antenna...
S1 - connected to 50' Rg58 via BNC connectors to my 10M dipole. The lowest piece of which is about 12' off of the ground. I set markers a L, M and H points of the band.
S2 port had nothing connected.
The VNA was calibrated just prior to the sweep. An anchored via USB to my Windows tablet.
Now I'm digging into how to read the Smith Chard and return / impedance info...
Comments please!!
Do I need to update VNA firmware or make other changes. Software on the tablet?
What's next folks?
|
Re: Touch screen does not respond well.
I'm know looking at the connector. Some have a lever the needs to be moved to remove the cable.
I don't see one, is the just a push in pull out ribbon? i.e. no moving of any levers to get the cable out.
OK, I disconnected the battery, poked and prodded at the ribbon cable, reconnected the battery and tested it with the cover off.
After this it responds to the touch pad commands much better than before, it's not perfect but usable.
Now, after a little more use it is getting flaky to the touch again. Any logical reason for this?
Thanks, Mikek
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Re: Touch screen does not respond well.
Make certain that there is nothing touching the screen (masking film remnants, mounting hardware) and interfering with your touch, loosening/removing the screws may be helpful.
73, Don N2VGU
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On Sat, Jan 11, 2025 at 4:19?PM va3rr via groups.io <va3rr= [email protected]> wrote: Nizar - I'm only a casual H4 user. You may wish to pose this question to
DiSlord, who is a prolific writer of H4 firmware. There may also be
answers in the wiki. /g/nanovna-users/wiki
vy 73 de Russ, va3rr
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Nizar - I'm only a casual H4 user. You may wish to pose this question to DiSlord, who is a prolific writer of H4 firmware. There may also be answers in the wiki. /g/nanovna-users/wikivy 73 de Russ, va3rr
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All,
We have reached our goal of raising another year's annual groups.io fee for this group. Thanks to everyone who contributed. I have to write that this was accomplished in less than 24 hours, which is remarkably fast.
*No more donations are needed.*
Thank you again.
DaveD
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On 1/10/2025 11:06 AM, Dave Daniel wrote: All,
It's that time of year again when we need to pay the annual $220 fee to keep the group going. The payment is due? the 18th and will be automatically paid by me.
Once again I ask that anyone who can contribute a few dollars is encouraged to do so. Here are the guidelines:
1. Every donation is appreciated by the group.
2. I will keep a log of all donations in chronological order. Assuming that the donation total reaches the $220 amount necessary, I will let the group know that we have enough to pay the fee.
3. Any donations that are made after the $220 goal has been reached will be returned. I do not have a good way to bank or track excess funds. Excess donations usually occur because of emails crossing in time, or me just getting busy.
4. All donations should be paid to me using PayPal "Friends and Family" (I am not making any money on this, obviously). My PayPal account is the same as my email address - kc0wjn at gmail dot com.
5. All donations will be kept in my (non-interest-bearing) PayPal account until I have paid the fee, after which time I will transfer the donated funds to my bank account.
6. In the past I have tried to personally acknowledge every individual contribution. I'll try to do that again this year, but I may not be able to for various reasons.
Thank you.
Dave Daniel, co-owner
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Hi VA3RR
Thanks a lot for the help.
I conlude that MS5153 may be a little bit better to go up to 300Mhz lnstead of 290Mhz for SI5351A and also a little bit better for harmonics measurement with few db deeper, the jitter noise do not conserne our NanoVNA typical application , no matter how it is with both,
But wondering why firmware do not consider them as similare sheeps , what can be the changes with firmware ?
73s. Nizar
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On Fri, Jan 10, 2025 at 05:06 PM, Dave Daniel wrote:
Friends and Family
Donated , thanks for the service Maurizio IZ1MDJ
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David KK7WXV
Dan Pate - AI5OL
Donald S Brant Jr
va3rr