The max frequency is probably more about where losses get too big.
And they’ll measure for a very wide range. Most design tools can deal with staying away from the SRF, if supplied with the part parameters.
After all, at microwave frequencies most parts have a very complex and varying impedance.
toggle quoted message
Show quoted text
On Apr 2, 2025, at 15:34, Brian Beezley <k6sti@...> wrote:
?By coincidence, I just added an image showing capacitance and dissipation factor plotted by my S-parameter plotter. It was derived from an .s2p file provided by Kyocera. Scroll to the last image:
One thing I don't understand. Manufacturers specify useful frequencies several times the capacitor self-resonant frequency, as revealed by the .s2p files they supply. The 33 pF shown departs from 33 pF as it approaches its 1.6 GHz SRF, which is nowhere near the 10 GHz specified upper frequency limit. All the capacitor manufacturers seems to do this. Why?
Brian
|
Re: Jittery , non steady readings
Yes, it is Zack W9SZ On Wed, Apr 2, 2025, 4:12 PM Dave Brown via groups.io <2c39a= [email protected]> wrote: Is the measurement frequency stable?
Dave
ZL3FJ
-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf
Of Zack Widup via groups.io
Sent: Thursday, April 03, 2025 06:14
To: [email protected]
Subject: Re: [nanovna-users] Jittery , non steady readings
I have consistently had this problem measuring inductors, capacitors and
resistors. Just recently I measured a silver mica capacitor that was around
3400 pF. I measured at 475 kHz (630 meter amateur band). As I watched the
display, every time I got a new measurement I would see something like
3420.1
3416.3
3411.8
3418.6
3422.5
3424.2
etc.
I took the average of the measurements as the value. But I don't know why
this was happening. The same happens with resistors and inductors. I could
see the inductors as most likely to pick up radio signals. But I do not
live close to a radio station or any service that is transmitting near me
(as noted on a TinySA). I turned off my wifi and got the same results.
I use a right angle SMA connector with a wire about 3 inches long going
through the opening and soldered to the center pin contact, also another
wire about 3 inches long soldered to the SMA body. I solder the other ends
of the wires to the device under test.
Zack W9SZ
On Tue, Apr 1, 2025 at 2:51?PM kellogs via groups.io <mihai0226=
[email protected]> wrote:
Is it normal for the readings to fluctuate as much as 2-3 ohms ? As in
11+/-1.5 - j(70+/-1.5)
Dipole NMHA (antenna), balun, calibrated, two ferrites: one at the
balun and one at the VNA S11 port. No body / coax inadvertent
movements, everything taped down near the antenna.
Thanks
<
Virus-free.www.avg.com
<
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
|
By coincidence, I just added an image showing capacitance and dissipation factor plotted by my S-parameter plotter. It was derived from an .s2p file provided by Kyocera. Scroll to the last image:
One thing I don't understand. Manufacturers specify useful frequencies several times the capacitor self-resonant frequency, as revealed by the .s2p files they supply. The 33 pF shown departs from 33 pF as it approaches its 1.6 GHz SRF, which is nowhere near the 10 GHz specified upper frequency limit. All the capacitor manufacturers seems to do this. Why?
Brian
|
Re: Jittery , non steady readings
Is the measurement frequency stable?
Dave
ZL3FJ
toggle quoted message
Show quoted text
-----Original Message----- From: [email protected] [mailto: [email protected]] On Behalf Of Zack Widup via groups.io Sent: Thursday, April 03, 2025 06:14 To: [email protected]Subject: Re: [nanovna-users] Jittery , non steady readings I have consistently had this problem measuring inductors, capacitors and resistors. Just recently I measured a silver mica capacitor that was around 3400 pF. I measured at 475 kHz (630 meter amateur band). As I watched the display, every time I got a new measurement I would see something like 3420.1 3416.3 3411.8 3418.6 3422.5 3424.2 etc. I took the average of the measurements as the value. But I don't know why this was happening. The same happens with resistors and inductors. I could see the inductors as most likely to pick up radio signals. But I do not live close to a radio station or any service that is transmitting near me (as noted on a TinySA). I turned off my wifi and got the same results. I use a right angle SMA connector with a wire about 3 inches long going through the opening and soldered to the center pin contact, also another wire about 3 inches long soldered to the SMA body. I solder the other ends of the wires to the device under test. Zack W9SZ On Tue, Apr 1, 2025 at 2:51?PM kellogs via groups.io <mihai0226= [email protected]> wrote: Is it normal for the readings to fluctuate as much as 2-3 ohms ? As in
11+/-1.5 - j(70+/-1.5)
Dipole NMHA (antenna), balun, calibrated, two ferrites: one at the
balun and one at the VNA S11 port. No body / coax inadvertent
movements, everything taped down near the antenna.
Thanks
<> Virus-free.www.avg.com <> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
|
On 2025-04-02 01:03, Fran?ois via groups.io wrote: Too bad it doesn't lead to any practical use. What do you expect me to do with a deadly formula like this?
Fran?ois, on dit en anglais <<maths moche!>>, "ugly math". John, at radio station VE7AOV.
|
Re: Jittery , non steady readings
I have consistently had this problem measuring inductors, capacitors and resistors. Just recently I measured a silver mica capacitor that was around 3400 pF. I measured at 475 kHz (630 meter amateur band). As I watched the display, every time I got a new measurement I would see something like 3420.1 3416.3 3411.8 3418.6 3422.5 3424.2 etc. I took the average of the measurements as the value. But I don't know why this was happening. The same happens with resistors and inductors. I could see the inductors as most likely to pick up radio signals. But I do not live close to a radio station or any service that is transmitting near me (as noted on a TinySA). I turned off my wifi and got the same results. I use a right angle SMA connector with a wire about 3 inches long going through the opening and soldered to the center pin contact, also another wire about 3 inches long soldered to the SMA body. I solder the other ends of the wires to the device under test. Zack W9SZ On Tue, Apr 1, 2025 at 2:51?PM kellogs via groups.io <mihai0226= [email protected]> wrote: Is it normal for the readings to fluctuate as much as 2-3 ohms ? As in
11+/-1.5 - j(70+/-1.5)
Dipole NMHA (antenna), balun, calibrated, two ferrites: one at the balun
and one at the VNA S11 port. No body / coax inadvertent movements,
everything taped down near the antenna.
Thanks
<> Virus-free.www.avg.com <> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
|
Re: Jittery , non steady readings
I live in a quiet neighbourhood; the antenna measures 8 cm from tip to tip. I shall take some measurements at the countryside and report back when I do.
|
Too bad it doesn't lead to any practical use. What do you expect me to do with a deadly formula like this?
--
F1AMM
Fran?ois
|
Re: Jittery , non steady readings
I was thinking that such fluctuations seen in NanoVNA were due to swinging of my multi-band fan dipole in the wind! That would change the relative nearness of elements to each other and nearby structures. Jon, VU2JO On Wed, Apr 2, 2025 at 4:33?AM W0LEV via groups.io <davearea51a= [email protected]> wrote: If you have a close-by strong source of RF energy like FM or AM
broadcasters, police, ambulance, CB'ers, hams, ....... any of those and
more could be affecting the readings. This is not all that uncommon in
cities when the VNA is connected to a large antenna.
Dave - W?LEV
On Tue, Apr 1, 2025 at 7:51?PM kellogs via groups.io <mihai0226=
[email protected]> wrote:
Is it normal for the readings to fluctuate as much as 2-3 ohms ? As in
11+/-1.5 - j(70+/-1.5)
Dipole NMHA (antenna), balun, calibrated, two ferrites: one at the balun
and one at the VNA S11 port. No body / coax inadvertent movements,
everything taped down near the antenna.
Thanks
--
*Dave - W?LEV*
--
Dave - W?LEV
|
Re: Jittery , non steady readings
Or to put it simply, the VNA contains a highly specialized radio receiver. On Tue, 1 Apr 2025 23:03:04 +0000 "W0LEV via groups.io" <davearea51a@...> wrote: If you have a close-by strong source of RF energy like FM or AM
broadcasters, police, ambulance, CB'ers, hams, ....... any of those and
more could be affecting the readings. This is not all that uncommon in
cities when the VNA is connected to a large antenna.
Dave - W?LEV
On Tue, Apr 1, 2025 at 7:51?PM kellogs via groups.io <mihai0226=
[email protected]> wrote:
Is it normal for the readings to fluctuate as much as 2-3 ohms ? As in
11+/-1.5 - j(70+/-1.5)
Dipole NMHA (antenna), balun, calibrated, two ferrites: one at the balun
and one at the VNA S11 port. No body / coax inadvertent movements,
everything taped down near the antenna.
Thanks -- 73 -Jim NU0C
|
Nothing.. just some places block accesses to various countries, so finding alternate ways to get there is useful.
There was a time when .int was resolved through a DNS server in China, which is blocked from government networks in the US. So if you had an alternate .org name, it was useful.
toggle quoted message
Show quoted text
On Mar 31, 2025, at 15:55, Dragan Milivojevic via groups.io <d.milivojevic@...> wrote:
?Your first link redirects to the same url the OP posted but I got to ask:
What is your issue with the paper being hosted in Bosnia&Hertzegovina,
the paper originated there.
On Mon, 31 Mar 2025 at 20:44, Jim Lux via groups.io <jimlux=
[email protected]> wrote:
Other sources that are in other countries than Bosnia Hertzegovina
The authors have a number of other interesting "measure component with a
VNA"
Measuring impedances of DC-biased inductors by using vector network
analyzers
|
Re: Jittery , non steady readings
If you have a close-by strong source of RF energy like FM or AM broadcasters, police, ambulance, CB'ers, hams, ....... any of those and more could be affecting the readings. This is not all that uncommon in cities when the VNA is connected to a large antenna. Dave - W?LEV On Tue, Apr 1, 2025 at 7:51?PM kellogs via groups.io <mihai0226= [email protected]> wrote: Is it normal for the readings to fluctuate as much as 2-3 ohms ? As in
11+/-1.5 - j(70+/-1.5)
Dipole NMHA (antenna), balun, calibrated, two ferrites: one at the balun
and one at the VNA S11 port. No body / coax inadvertent movements,
everything taped down near the antenna.
Thanks
-- *Dave - W?LEV* -- Dave - W?LEV
|
Jittery , non steady readings
Is it normal for the readings to fluctuate as much as 2-3 ohms ? As in 11+/-1.5 - j(70+/-1.5)
Dipole NMHA (antenna), balun, calibrated, two ferrites: one at the balun and one at the VNA S11 port. No body / coax inadvertent movements, everything taped down near the antenna.
Thanks
|
Re: NANO VNA H4 , Implausible measurement results?
No, but a guy may have already worked DXCC while you're still arguing about whether an antenna is good or not. Get on and use it. Play with it later as needed. Zack W9SZ <> Virus-free.www.avg.com <> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> On Tue, Apr 1, 2025 at 10:34?AM W0LEV via groups.io <davearea51a= [email protected]> wrote: QUOTE: However a successful QSO is not scientific evidence of a "good" or
"bad" antenna.
If it works, great. But do not use this as evidence of optimum antenna
performance:-)
**
I'd also add that a low SWR is also not an appropriate means of declaring
an antenna good.
Dave - W?LEV
On Tue, Apr 1, 2025 at 6:59?AM Bob Ecclestone VK2ZRE via groups.io
<becclest@...> wrote:
Hello Jon,
As you wish to use the antenna on the higher harmonics as well as 2M, I
would suggest you use ferrites to create a Common Mode Choke (CMC) as
noted by Roger.
I suspect (but do not know, I am no expert here) that it would be
difficult to build a broadband balun to cover your frequency range (x5,
x7) at TX power levels.
As for some of the other comments to this thread, I did not say that
your antenna would not work without a balun or CMC.
What I said was that without a balun or CMC, the connection of an
unbalanced VNA to a balanced dipole would not give correct measurement
results of the antenna because the feedline would become part of the
antenna measurement as also noted in other responses in this thread.
Your experience when you used a replacement "load" to do your
calibration just emphasises how critical it is to do calibrations
correctly and to treat your calibration SOLT "standards" with care and
respect.
We can measure antennas till the cows come home and hypothesize on the
results for twice as long, but we all know that the most unlikely
collection of bits and bobs will form some sort of antenna that may, or
may not, enable QSOs one way or the other. However a successful QSO is
not scientific evidence of a "good" or "bad" antenna.
If it works, great. But do not use this as evidence of optimum antenna
performance:-)
The "suck it and see" approach may not quite equate to measured
results:-) Just my 2 cents worth.
Cheers...Bob VK2ZRE
On 1/04/2025 12:25 am, Jon via groups.io wrote:
Bob,
Would you suggest a voltage balun or current balun at antenna feedpoint?
One ham told me that if you use a voltage balun, it can bring down the high
noise I have on 80m.
Regarding the original question, I am tempted to think like Milt. I
see a
lot of harmonic resonance in NanoVNA tracings when I set the range high on
purpose. In fact I use them to work higher bands. I am able to work
North
America from VU on 12m, using my 80m center-fed dipole mounted at just
5m
height and 100W, with a little bit of touching up with the N7DDC tuner.
That would be the seventh harmonic resonance!
73
Jon, VU2JO
On Mon, Mar 31, 2025 at 6:29?PM Bob Ecclestone VK2ZRE via groups.io
<becclest@...> wrote:
Hello Hobride,
Unfortunately you have not supplied a photo of your test setup.
A dipole is balanced at the feedpoint, your VNA is unbalanced.
I suspect your problem is that you do not have a balun or choke at the
antenna feedpoint to prevent the feeder from affecting the
measurement.
I won't make any guess as to why the VSWR appears lowest at 513MHz,
but
I do suggest you use a balun or choke at the antenna.
HTH...Bob VK2ZRE
On 31/03/2025 11:25 pm, Milton Engle via groups.io wrote:
You did not indicate the range of your sweep.
Try setting the sweep range to 150MHz to 190MHz, recalibrate open/short/load, then measure.
I suspect that you will find the lowest VSWR near 171MHz, indicating that the element lengths are a bit long.
The third harmonic of 171 is 513
Milt
N3LTQ
On Mar 31, 2025, at 03:51, hobride via groups.io <hobride= [email protected]> wrote:
?Hello everyone,
I have bought a NANO VNA H4 to build simple dipole antennas.
Now I have made a simple dipole antenna for testing. This should be
tuned for 172 MHz. The total length is ~83 cm (2,72 feet), one leg is
~41.5
cm (1,36 feet).
When I now connect this antenna and try to measure it, the result
is a
lowest SWR (1.15) at 513 MHz.
Can this be possible? I am not a radio specialist. I am an IT guy.
I have flashed the NANO VNA H4 to the latest firmware (tried DiSlord
and Hugen) and also calibrated it.
Perhaps I need to make further settings after flashing?
--
*Dave - W?LEV*
--
Dave - W?LEV
|
Yes. Alan is one of the "big boys" and belongs to Tek. Those by amateurs and others may be highly questionable. At least those are my experiences with YouToob. For example, addressing ferrites, Fair-Rite has a wonderfully useful and solid site, even some directly aimed at the amateur radio community. So do Agilent, Tek, Keysite, Advantest, R&S, HP, and many.....many others. To properly utilize YouToob presentations, one must first know at least the basics of the knowledge they are seeking. Without a basic knowledge, you are highly likely to be "snake oiled" and "witchcrafted" and "sorceried" and....... Dave - W?LEV On Tue, Apr 1, 2025 at 4:03?PM Donald S Brant Jr via groups.io <dsbrantjr= [email protected]> wrote: On Tue, Apr 1, 2025 at 11:36 AM, W0LEV wrote:
Beware of most YouToob presentations.
You can absolutely trust Alan Wolke W2AEW's videos. He is a Tektronix
Field Engineer, I know him personally and knows his stuff 100%.
And, to your original question you must be looking at S11 Smith Chart
display to see 50Ohms; S21 magnitude should be 0dB when the thru is
connected.
Best regards, Don Brant
-- *Dave - W?LEV* -- Dave - W?LEV
|
Even a linear wire, not coiled, has some measurable inductance. At zero length the display on the Smith chart, will show a single value of zero at the extreme left of the real axis. That point on the Smith Chart is 0.00.... ± j 0 ohms. That represents a short circuit. As the measurement point along the linear wire is increased, both the RF resistance (skin effect) and inductance increase. Therefore, the measurement will depart upward on the chart (inductive reactance) and to the right along the central line on the chart. Since the vast majority of RF measurements are assumed in a 50-ohm system (the industry standard except for the television people), the chart is laid out around that value. ONLY the central point (see the previous attachment) represents 50 ± j0 ohms. The extreme right position along the central axis (real only) represents an open circuit or theoretically infinite resistance. An excellent tool both for analysis, modeling, and learning the Smith Chart is SimSmith. It's free and available at the following URL: That URL also contains many good tutorials addressing the Smith Chart. More information can be had at the following: Dave - W?LEV On Tue, Apr 1, 2025 at 3:52?PM Jon via groups.io <vu2jo0@...> wrote: Dave,
One doubt about the Smith Chart: Why does the so-called resistive component
change as you move across the tracing? If it was the true electrical
resistance due to the ohmic resistance of the wire and feedline, it should
not change.
Forgive my ignorance. I have started using NanoVNA only recently.
73
VU2JO
On Tue, Apr 1, 2025 at 9:15?PM W0LEV via groups.io <davearea51a=
[email protected]> wrote:
Possibly the attachment will help.
Dave - W?LEV
On Tue, Apr 1, 2025 at 3:36?PM W0LEV via groups.io <davearea51a=
[email protected]> wrote:
Beware of most YouToob presentations. Those by the "big boys" which offer
their instruments for lots of $$$$ are good and solid. Many of those by
amateurs or "self proclaimed experts" are flawed. Take anything on YouToob
with a huge grain of salt!!
Dave - W?LEV
On Tue, Apr 1, 2025 at 1:59?PM Zack Widup via groups.io <w9sz.zack=
[email protected]> wrote:
If the video on Youtube notes that the impedance should be zero, it
is
incorrect. The THRU impedance should be 50 ohms. I just checked on
three
NanoVNA's, and they all measure 50 ohms.
Zack W9SZ
On Tue, Apr 1, 2025 at 8:48?AM Paolo via groups.io <paolo.vecchi=
[email protected]> wrote:
Hi, I have seen a video on Youtube…
NANOVNA analizzatore di antenne: come usarlo (
)
youtu.be ( )
( )
Inviato da iPhone
Il giorno 1 apr 2025, alle ore 15:39, Dragan Milivojevic via
groups.io
<d.milivojevic@...> ha scritto:
? Port 2 is 50Ω as it should be, why do you imagine that it would
be
0?
On Tue, 1 Apr 2025 at 14:14, paolo.vecchi via groups.io
<paolo.vecchi=
[email protected]> wrote:
I buyed a nanovna H 3.6. When I try to calibrate it, after the
full
procedure, if I set a Smith diagram and I connect THRU the two
ports
using
the supplied cable the value is 50 ohm instead of 0. I resetted
and
repeated the calibration a lot of time but with the same result.
Can
you
help me? Thanks
<
Virus-free.www.avg.com
<
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
--
*Dave - W?LEV*
--
Dave - W?LEV
--
*Dave - W?LEV*
--
Dave - W?LEV
-- *Dave - W?LEV* -- Dave - W?LEV
|
On Tue, Apr 1, 2025 at 11:36 AM, W0LEV wrote:
Beware of most YouToob presentations.
You can absolutely trust Alan Wolke W2AEW's videos. He is a Tektronix Field Engineer, I know him personally and knows his stuff 100%. And, to your original question you must be looking at S11 Smith Chart display to see 50Ohms; S21 magnitude should be 0dB when the thru is connected. Best regards, Don Brant
|
Dave, One doubt about the Smith Chart: Why does the so-called resistive component change as you move across the tracing? If it was the true electrical resistance due to the ohmic resistance of the wire and feedline, it should not change. Forgive my ignorance. I have started using NanoVNA only recently. 73 VU2JO On Tue, Apr 1, 2025 at 9:15?PM W0LEV via groups.io <davearea51a= [email protected]> wrote: Possibly the attachment will help.
Dave - W?LEV
On Tue, Apr 1, 2025 at 3:36?PM W0LEV via groups.io <davearea51a=
[email protected]> wrote:
Beware of most YouToob presentations. Those by the "big boys" which offer
their instruments for lots of $$$$ are good and solid. Many of those by
amateurs or "self proclaimed experts" are flawed. Take anything on YouToob
with a huge grain of salt!!
Dave - W?LEV
On Tue, Apr 1, 2025 at 1:59?PM Zack Widup via groups.io <w9sz.zack=
[email protected]> wrote:
If the video on Youtube notes that the impedance should be zero, it is
incorrect. The THRU impedance should be 50 ohms. I just checked on three
NanoVNA's, and they all measure 50 ohms.
Zack W9SZ
On Tue, Apr 1, 2025 at 8:48?AM Paolo via groups.io <paolo.vecchi=
[email protected]> wrote:
Hi, I have seen a video on Youtube…
NANOVNA analizzatore di antenne: come usarlo (
)
youtu.be ( )
( )
Inviato da iPhone
Il giorno 1 apr 2025, alle ore 15:39, Dragan Milivojevic via
groups.io
<d.milivojevic@...> ha scritto:
? Port 2 is 50Ω as it should be, why do you imagine that it would
be
0?
On Tue, 1 Apr 2025 at 14:14, paolo.vecchi via groups.io
<paolo.vecchi=
[email protected]> wrote:
I buyed a nanovna H 3.6. When I try to calibrate it, after the
full
procedure, if I set a Smith diagram and I connect THRU the two
ports
using
the supplied cable the value is 50 ohm instead of 0. I resetted
and
repeated the calibration a lot of time but with the same result.
Can
you
help me? Thanks
<
Virus-free.www.avg.com
<
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
--
*Dave - W?LEV*
--
Dave - W?LEV
--
*Dave - W?LEV*
--
Dave - W?LEV
|
Re: NANO VNA H4 , Implausible measurement results?
That being said, the aim of a radio amateur is to have a QSO, without damaging equipment and causing interference (RFI)! All these - balun, common mode choke, SWR meter and NanoVNA, are aids to achieve that end result. 73 Jon, VU2JO On Tue, Apr 1, 2025 at 9:04?PM W0LEV via groups.io <davearea51a= [email protected]> wrote: QUOTE: However a successful QSO is not scientific evidence of a "good" or
"bad" antenna.
If it works, great. But do not use this as evidence of optimum antenna
performance:-)
**
I'd also add that a low SWR is also not an appropriate means of declaring
an antenna good.
Dave - W?LEV
On Tue, Apr 1, 2025 at 6:59?AM Bob Ecclestone VK2ZRE via groups.io
<becclest@...> wrote:
Hello Jon,
As you wish to use the antenna on the higher harmonics as well as 2M, I
would suggest you use ferrites to create a Common Mode Choke (CMC) as
noted by Roger.
I suspect (but do not know, I am no expert here) that it would be
difficult to build a broadband balun to cover your frequency range (x5,
x7) at TX power levels.
As for some of the other comments to this thread, I did not say that
your antenna would not work without a balun or CMC.
What I said was that without a balun or CMC, the connection of an
unbalanced VNA to a balanced dipole would not give correct measurement
results of the antenna because the feedline would become part of the
antenna measurement as also noted in other responses in this thread.
Your experience when you used a replacement "load" to do your
calibration just emphasises how critical it is to do calibrations
correctly and to treat your calibration SOLT "standards" with care and
respect.
We can measure antennas till the cows come home and hypothesize on the
results for twice as long, but we all know that the most unlikely
collection of bits and bobs will form some sort of antenna that may, or
may not, enable QSOs one way or the other. However a successful QSO is
not scientific evidence of a "good" or "bad" antenna.
If it works, great. But do not use this as evidence of optimum antenna
performance:-)
The "suck it and see" approach may not quite equate to measured
results:-) Just my 2 cents worth.
Cheers...Bob VK2ZRE
On 1/04/2025 12:25 am, Jon via groups.io wrote:
Bob,
Would you suggest a voltage balun or current balun at antenna feedpoint?
One ham told me that if you use a voltage balun, it can bring down the high
noise I have on 80m.
Regarding the original question, I am tempted to think like Milt. I
see a
lot of harmonic resonance in NanoVNA tracings when I set the range high on
purpose. In fact I use them to work higher bands. I am able to work
North
America from VU on 12m, using my 80m center-fed dipole mounted at just
5m
height and 100W, with a little bit of touching up with the N7DDC tuner.
That would be the seventh harmonic resonance!
73
Jon, VU2JO
On Mon, Mar 31, 2025 at 6:29?PM Bob Ecclestone VK2ZRE via groups.io
<becclest@...> wrote:
Hello Hobride,
Unfortunately you have not supplied a photo of your test setup.
A dipole is balanced at the feedpoint, your VNA is unbalanced.
I suspect your problem is that you do not have a balun or choke at the
antenna feedpoint to prevent the feeder from affecting the
measurement.
I won't make any guess as to why the VSWR appears lowest at 513MHz,
but
I do suggest you use a balun or choke at the antenna.
HTH...Bob VK2ZRE
On 31/03/2025 11:25 pm, Milton Engle via groups.io wrote:
You did not indicate the range of your sweep.
Try setting the sweep range to 150MHz to 190MHz, recalibrate open/short/load, then measure.
I suspect that you will find the lowest VSWR near 171MHz, indicating that the element lengths are a bit long.
The third harmonic of 171 is 513
Milt
N3LTQ
On Mar 31, 2025, at 03:51, hobride via groups.io <hobride= [email protected]> wrote:
?Hello everyone,
I have bought a NANO VNA H4 to build simple dipole antennas.
Now I have made a simple dipole antenna for testing. This should be
tuned for 172 MHz. The total length is ~83 cm (2,72 feet), one leg is
~41.5
cm (1,36 feet).
When I now connect this antenna and try to measure it, the result
is a
lowest SWR (1.15) at 513 MHz.
Can this be possible? I am not a radio specialist. I am an IT guy.
I have flashed the NANO VNA H4 to the latest firmware (tried DiSlord
and Hugen) and also calibrated it.
Perhaps I need to make further settings after flashing?
--
*Dave - W?LEV*
--
Dave - W?LEV
|
Possibly the attachment will help. Dave - W?LEV On Tue, Apr 1, 2025 at 3:36?PM W0LEV via groups.io <davearea51a= [email protected]> wrote: Beware of most YouToob presentations. Those by the "big boys" which offer
their instruments for lots of $$$$ are good and solid. Many of those by
amateurs or "self proclaimed experts" are flawed. Take anything on YouToob
with a huge grain of salt!!
Dave - W?LEV
On Tue, Apr 1, 2025 at 1:59?PM Zack Widup via groups.io <w9sz.zack=
[email protected]> wrote:
If the video on Youtube notes that the impedance should be zero, it is
incorrect. The THRU impedance should be 50 ohms. I just checked on three
NanoVNA's, and they all measure 50 ohms.
Zack W9SZ
On Tue, Apr 1, 2025 at 8:48?AM Paolo via groups.io <paolo.vecchi=
[email protected]> wrote:
Hi, I have seen a video on Youtube…
NANOVNA analizzatore di antenne: come usarlo (
)
youtu.be ( )
( )
Inviato da iPhone
Il giorno 1 apr 2025, alle ore 15:39, Dragan Milivojevic via
groups.io
<d.milivojevic@...> ha scritto:
? Port 2 is 50Ω as it should be, why do you imagine that it would be
0?
On Tue, 1 Apr 2025 at 14:14, paolo.vecchi via groups.io
<paolo.vecchi=
[email protected]> wrote:
I buyed a nanovna H 3.6. When I try to calibrate it, after the full
procedure, if I set a Smith diagram and I connect THRU the two ports using
the supplied cable the value is 50 ohm instead of 0. I resetted and
repeated the calibration a lot of time but with the same result. Can
you
help me? Thanks
<
Virus-free.www.avg.com
<
<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
--
*Dave - W?LEV*
--
Dave - W?LEV
-- *Dave - W?LEV* -- Dave - W?LEV
|
Jim Shorney
Donald S Brant Jr
