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Hi All,
I am a new owner of the nano vna and i am not really sure how to read the results of the plots.
Originally i had just strung up a random wire between my garage and back fence and i have
since been playing with a Gypsy antenna i ordered off alliexpress.
Ant1 is the gypsy unit and i should note that i don't have the feed point exactly center so its more like an offset center
feed at the moment
Ant2 is my end fed random wire
For Ant1 the antenna has a 1:1 balon connected to the 2 wires of the antenna and i have 50ft of rg58au between that and the radio
For Ant2 i have a random wire with the center conductor of a piece of coax attached to the wire and the shield of coax is connected to a copper ground rod outside
here is what i don't understand
with Ant2 i can hear a time signal at over 9 s units on USB at 3.330.00 Mhz and i can hear all my local AM radio stations loud and clear.
with Ant1 i cannot hear local AM stations at all and can just barely hear the time signal at the freq above.
My rig is TS-440s
Is it possible i messed up the connectors on the coax, i would have expected the new ant to preform better but is does seem to be way worse than a random piece of wire.
In both case the wires are about 50 to 60 feet long and only running about 6 ft off the ground.
Can someone explain the data in the pictures is there any info in it that would tell me why the gypsy cannot even receive a local AM station i would have though it would at least do as well as the random wire which is just a length of 12v power wire that is stranded that i had in my junk box.
I can provide more info in need any help would be appreciated
73 de VE3SJK
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The Gypsy antenna looks quite loosy with only two real resonances. Those
being roughly 9 and 16.5 MHz. It hugs the outside of the Smith Chart which
indicates loss. Not a very good antenna in general.
Your long wire looks much less lossy with resonances at roughly 4 and 12
MHz.
With the lower resonance at 4 MHz of your long wire, it will be FAR more
capable of receiving AM BC and your time signal at 3.300 MHz. The Gypsy
antenna might be good for SWRing after Cycle 25 really gets going, but for
AM BC and 3.300 MHz reception, put it on the shelf for another three or so
years.
Dave - W?LEV
toggle quoted message
Show quoted text
On Sun, Nov 1, 2020 at 9:49 PM <deadman1966@...> wrote: Hi All,
I am a new owner of the nano vna and i am not really sure how to read the
results of the plots.
Originally i had just strung up a random wire between my garage and back
fence and i have
since been playing with a Gypsy antenna i ordered off alliexpress.
Ant1 is the gypsy unit and i should note that i don't have the feed point
exactly center so its more like an offset center
feed at the moment
Ant2 is my end fed random wire
For Ant1 the antenna has a 1:1 balon connected to the 2 wires of the
antenna and i have 50ft of rg58au between that and the radio
For Ant2 i have a random wire with the center conductor of a piece of coax
attached to the wire and the shield of coax is connected to a copper ground
rod outside
here is what i don't understand
with Ant2 i can hear a time signal at over 9 s units on USB at 3.330.00
Mhz and i can hear all my local AM radio stations loud and clear.
with Ant1 i cannot hear local AM stations at all and can just barely hear
the time signal at the freq above.
My rig is TS-440s
Is it possible i messed up the connectors on the coax, i would have
expected the new ant to preform better but is does seem to be way worse
than a random piece of wire.
In both case the wires are about 50 to 60 feet long and only running about
6 ft off the ground.
Can someone explain the data in the pictures is there any info in it that
would tell me why the gypsy cannot even receive a local AM station i would
have though it would at least do as well as the random wire which is just a
length of 12v power wire that is stranded that i had in my junk box.
I can provide more info in need any help would be appreciated
73 de VE3SJK
--
*Dave - W?LEV*
*Just Let Darwin Work*
|
Is it possible all the loss is in the coax itself i did the connectors myself and its been many years since i did one, the cable i used was stuff off of amazon. I am going to try and install the nanovna on my Ubuntu notebook and take a reading at the antenna with a short jumper to the vna and measure the antenna itself sure sounds like it was a waste of money other wise but i can still use the wires. I also wonder it this is due to the fact the 1:1 is not on centre of the span either. I am trying to find my best layout for an antenna in my back yard but its almost impossible for me to use an antenna that is centre fed the yard is 60ft wide and i have 97 feet from back of house to 6ft fence the house is 30 feet high i was thinking of some kind of end feed wire that sloped from the house to the 6ft wood fence in the back. I have also ordered a 100ft length of rg8x with the connectors done at factor should have it in a day or so to compare readings. Pretty new to HF the kenwood TS-440 is the first all band unit for me.
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Get yourself an antenna tuning unit (ATU). If doing receive only you will need a manual type as the automatic ones need a few watts of tx power to detect a bad match.
You can use the VNA to help tune to a particular frequency. The closer the original match is to the outside of the Smith chart the harder it is to match and the narrower any tuning will be.
Btw, hugging the outside of the Smith chart does NOT indicate loss. It indicates reflection. Loss tends to make the match look better than it really is.
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Disconnect your antenna and leave the koax open. Then measure the reflexion factor in dB at the other side of the koax. The loss in koax is now half the reading of the reflexion factor at each frequency.
73, G¨¹nter, DK5DN
Am 02.11.2020 um 05:14 schrieb deadman1966@...:
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Show quoted text
Is it possible all the loss is in the coax itself i did the connectors myself and its been many years since i did one, the cable i used was stuff off of amazon. I am going to try and install the nanovna on my Ubuntu notebook and take a reading at the antenna with a short jumper to the vna and measure the antenna itself sure sounds like it was a waste of money other wise but i can still use the wires. I also wonder it this is due to the fact the 1:1 is not on centre of the span either. I am trying to find my best layout for an antenna in my back yard but its almost impossible for me to use an antenna that is centre fed the yard is 60ft wide and i have 97 feet from back of house to 6ft fence the house is 30 feet high i was thinking of some kind of end feed wire that sloped from the house to the 6ft wood fence in the back. I have also ordered a 100ft length of rg8x with the connectors done at factor should have it in a day or so to compare readings. Pretty new to HF the kenwood TS-440 is the first all band unit for me.
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Hi VE3SJK,
Can you please sweep the antenna 1 from 500 kHz to 4 MHz?
Make sure you calbrated the vna first.
How long are the wires (exactly)?
How long is the coaxfeed between vna and antenna?
If connectors are not in order, all kind of things may happen and show up in the charts. So please check those.
It would not hurt to rf-isolate the vna from the computer by a common mode choke in the usb wire to the pc. (been there :-) )
73
Arie PA3A
Op 1-11-2020 om 22:49 schreef deadman1966@...:
toggle quoted message
Show quoted text
Hi All,
I am a new owner of the nano vna and i am not really sure how to read the results of the plots.
Originally i had just strung up a random wire between my garage and back fence and i have
since been playing with a Gypsy antenna i ordered off alliexpress.
Ant1 is the gypsy unit and i should note that i don't have the feed point exactly center so its more like an offset center
feed at the moment
Ant2 is my end fed random wire
For Ant1 the antenna has a 1:1 balon connected to the 2 wires of the antenna and i have 50ft of rg58au between that and the radio
For Ant2 i have a random wire with the center conductor of a piece of coax attached to the wire and the shield of coax is connected to a copper ground rod outside
here is what i don't understand
with Ant2 i can hear a time signal at over 9 s units on USB at 3.330.00 Mhz and i can hear all my local AM radio stations loud and clear.
with Ant1 i cannot hear local AM stations at all and can just barely hear the time signal at the freq above.
My rig is TS-440s
Is it possible i messed up the connectors on the coax, i would have expected the new ant to preform better but is does seem to be way worse than a random piece of wire.
In both case the wires are about 50 to 60 feet long and only running about 6 ft off the ground.
Can someone explain the data in the pictures is there any info in it that would tell me why the gypsy cannot even receive a local AM station i would have though it would at least do as well as the random wire which is just a length of 12v power wire that is stranded that i had in my junk box.
I can provide more info in need any help would be appreciated
73 de VE3SJK
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On Mon, Nov 2, 2020 at 08:06 AM, schweppe wrote: Disconnect your antenna and leave the koax open. Then measure the
reflexion factor in dB at the other side of the koax. The loss in koax
is now half the reading of the reflexion factor at each frequency. You do get 'ringing' (reflections) right across the frequency range when you measure coax loss using just the S11 reading. So you will get a large variation depending on whether the far end of the coax is open or short. You can use either a short or an open(either is fine) so long as you take into account this 'ringing'. This graph will shows this 'ringing' and so shows what it looks like and shows the two different S11 readings, one for open coax and one for short coax. At the low frequency end (left) their basically 180 deg out of phase, but then change to almost in-phase at the high frequency end (right). I added a coax loss graph (top right) that removes the 'ringing' and shows a readable coax loss from both a far end open or short (same result from either/both), it also shows the short/open end impedance on the bottom right graph and the coax length on the bottom left graph ..
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and again on one of the short patch leads on the VNA (S11 coax loss measurement) ..
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On 11/1/20 10:12 PM, HexAndFlex via groups.io wrote: Get yourself an antenna tuning unit (ATU). If doing receive only you will need a manual type as the automatic ones need a few watts of tx power to detect a bad match. At low frequencies on receive, the mismatch may not hurt you all that much - the input Z of the receiver probably isn't all that closely controlled. The noise figure of most HF receivers isn't all that hot either, since the dominant limit on received SNR is the atmospheric and environmental noise. Easy test - if you connect the antenna, does the noise go up? If so, then you're fine. You can use the VNA to help tune to a particular frequency. The closer the original match is to the outside of the Smith chart the harder it is to match and the narrower any tuning will be.
Btw, hugging the outside of the Smith chart does NOT indicate loss. It indicates reflection. Loss tends to make the match look better than it really is.
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You get ringing only if you have more than one reflexion on cable. Maybe by bad connector at the start of cable or by using cable impedance other than 50 Ohm.
See attached simulated file.
74, G¨¹nter, DK5DN
Am 02.11.2020 um 10:02 schrieb OneOfEleven:
toggle quoted message
Show quoted text
On Mon, Nov 2, 2020 at 08:06 AM, schweppe wrote:
Disconnect your antenna and leave the koax open. Then measure the
reflexion factor in dB at the other side of the koax. The loss in koax
is now half the reading of the reflexion factor at each frequency. You do get 'ringing' (reflections) right across the frequency range when you measure coax loss using just the S11 reading. So you will get a large variation depending on whether the far end of the coax is open or short. You can use either a short or an open(either is fine) so long as you take into account this 'ringing'.
This graph will shows this 'ringing' and so shows what it looks like and shows the two different S11 readings, one for open coax and one for short coax. At the low frequency end (left) their basically 180 deg out of phase, but then change to almost in-phase at the high frequency end (right). I added a coax loss graph (top right) that removes the 'ringing' and shows a readable coax loss from both a far end open or short (same result from either/both), it also shows the short/open end impedance on the bottom right graph and the coax length on the bottom left graph ..
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Thank you, HexandFlex. I should have had less Tequila when I wrote that. Loss on the Smith Chart is indicated as hugging the center of the chart. Low loss but bad match overall would write the outside of the chart. My error. That's for the correction. Dave - W?LEV On Mon, Nov 2, 2020 at 6:12 AM HexAndFlex via groups.io <iain_haggis= [email protected]> wrote: Get yourself an antenna tuning unit (ATU). If doing receive only you will
need a manual type as the automatic ones need a few watts of tx power to
detect a bad match.
You can use the VNA to help tune to a particular frequency. The closer the
original match is to the outside of the Smith chart the harder it is to
match and the narrower any tuning will be.
Btw, hugging the outside of the Smith chart does NOT indicate loss. It
indicates reflection. Loss tends to make the match look better than it
really is.
-- *Dave - W?LEV* *Just Let Darwin Work*
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EDIT
I got 100ft of RG8X coax today and a gas tube lightning arrest delivered today.
I have added some more plots after doing some testing.
First i plotted after just replacing the coax going from that 50ft amazon stuff with my connectors to 100 feet of RG8X with factory connectors
I then moved the antenna diagonally in my yard and stretched out the gypsy equally on each side. There is exactly 21 1/4 inches of wire out
past the 7Mhz silver marker on the wire on each side of the antenna. Its still only 6 feed off the ground though.
SInce I had a ton of extra coax in the garage and i was at this point just playing with the nanoVNA i measured aproximately 19 feet of coax
and wound it tight around a cardboard tube i had in the garage that was 2 5/8 inch diameter and took another scan which didn't show any
change really.
Not sure if i should leave this RF Choke on it as i will be transmitting and I don't know what effects it will have maybe someone could shed insight into why
i should remove or keep it on there.
The last scan is the entire setup from 30Khz to 1.2Ghz
The antenna is running pretty well right on the line of North to South in my location
First Impressions with the Kenwood TS-440 i had a 59+10 wefax signal at 6338.60 that was amazing
A quick scan AM Broadcast is not that good so i don't think the low end gonna be very useful.
A quick scan at 9Mhz up gave me at least 7 am stations i have never heard before all at 59+10 or more although some faded out as it got darker. I station i identified was WRMI at 9.955.00. Anywhere around 7Mhz had lots of chatter on side band.
The kenwood has a tuner so if anyone can give me any insight from the plots where i may not want to try and tune or transmit would be great. I am really interested in all of the data modes that are out there. Flurries and high winds here so hopefully i get a nice day in the future to get it higher in the air.
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To get a far better idea of what is going, please use 10 segments instead
of one. The present data is too disjointed to make any real conclusions.
The segment setting is in the upper left of the NANOSAVER window.
[image: image.png]
Dave - W?LEV
toggle quoted message
Show quoted text
On Tue, Nov 3, 2020 at 12:04 AM <deadman1966@...> wrote: EDIT
I got 100ft of RG8X coax today and a gas tube lightning arrest delivered
today.
I have added some more plots after doing some testing.
First i plotted after just replacing the coax going from that 50ft amazon
stuff with my connectors to 100 feet of RG8X with factory connectors
I then moved the antenna diagonally in my yard and stretched out the gypsy
equally on each side. There is exactly 21 1/4 inches of wire out
past the 7Mhz silver marker on the wire on each side of the antenna. Its
still only 6 feed off the ground though.
SInce I had a ton of extra coax in the garage and i was at this point
just playing with the nanoVNA i measured aproximately 19 feet of coax
and wound it tight around a cardboard tube i had in the garage that was 2
5/8 inch diameter and took another scan which didn't show any
change really.
Not sure if i should leave this RF Choke on it as i will be transmitting
and I don't know what effects it will have maybe someone could shed insight
into why
i should remove or keep it on there.
The last scan is the entire setup from 30Khz to 1.2Ghz
The antenna is running pretty well right on the line of North to South in
my location
First Impressions with the Kenwood TS-440 i had a 59+10 wefax signal at
6338.60 that was amazing
A quick scan AM Broadcast is not that good so i don't think the low end
gonna be very useful.
A quick scan at 9Mhz up gave me at least 7 am stations i have never heard
before all at 59+10 or more although some faded out as it got darker. I
station i identified was WRMI at 9.955.00. Anywhere around 7Mhz had lots of
chatter on side band.
The kenwood has a tuner so if anyone can give me any insight from the
plots where i may not want to try and tune or transmit would be great. I am
really interested in all of the data modes that are out there. Flurries and
high winds here so hopefully i get a nice day in the future to get it
higher in the air.
--
*Dave - W?LEV*
*Just Let Darwin Work*
|
Also, ditch the S11 Phase display and the SWR display. You can add SWR
lines on the S11 display. Add SWR = 1.5, 2.0 and 3.0 lines.
You'll get larger, easier to read displays.
73, Carey WB4HXE
toggle quoted message
Show quoted text
On Mon, Nov 2, 2020 at 7:16 PM David Eckhardt <davearea51a@...> wrote: To get a far better idea of what is going, please use 10 segments instead
of one. The present data is too disjointed to make any real conclusions.
The segment setting is in the upper left of the NANOSAVER window.
[image: image.png]
Dave - W?LEV
On Tue, Nov 3, 2020 at 12:04 AM <deadman1966@...> wrote:
EDIT
I got 100ft of RG8X coax today and a gas tube lightning arrest delivered
today.
I have added some more plots after doing some testing.
First i plotted after just replacing the coax going from that 50ft amazon
stuff with my connectors to 100 feet of RG8X with factory connectors
I then moved the antenna diagonally in my yard and stretched out the gypsy
equally on each side. There is exactly 21 1/4 inches of wire out
past the 7Mhz silver marker on the wire on each side of the antenna. Its
still only 6 feed off the ground though.
SInce I had a ton of extra coax in the garage and i was at this point
just playing with the nanoVNA i measured aproximately 19 feet of coax
and wound it tight around a cardboard tube i had in the garage that was 2
5/8 inch diameter and took another scan which didn't show any
change really.
Not sure if i should leave this RF Choke on it as i will be transmitting
and I don't know what effects it will have maybe someone could shed insight
into why
i should remove or keep it on there.
The last scan is the entire setup from 30Khz to 1.2Ghz
The antenna is running pretty well right on the line of North to South in
my location
First Impressions with the Kenwood TS-440 i had a 59+10 wefax signal at
6338.60 that was amazing
A quick scan AM Broadcast is not that good so i don't think the low end
gonna be very useful.
A quick scan at 9Mhz up gave me at least 7 am stations i have never heard
before all at 59+10 or more although some faded out as it got darker. I
station i identified was WRMI at 9.955.00. Anywhere around 7Mhz had lots of
chatter on side band.
The kenwood has a tuner so if anyone can give me any insight from the
plots where i may not want to try and tune or transmit would be great. I am
really interested in all of the data modes that are out there. Flurries and
high winds here so hopefully i get a nice day in the future to get it
higher in the air.
--
*Dave - W?LEV*
*Just Let Darwin Work*
--
Carey Fisher
careyfisher@...
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On 2020-11-02 4:04 p.m., deadman1966@... wrote: ... Flurries and high winds here so hopefully i get a nice day in the future to get it higher in the air. Tsk. That's not ethical, OM; right now is the time. In the ham radio
tradition procrastination in antenna work is to continue until there is no choice by which point the weather /has/ become wet and windy! John
at radio station VE7AOV
--
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Is it cold enough? Remember, the performance of an antenna is inversely proportional to the temperature at the time it was erected. 73, Zack W9SZ <> Virus-free. www.avast.com <> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> On Tue, Nov 3, 2020 at 12:57 AM John Nightingale via groups.io <if455kc= [email protected]> wrote:
On 2020-11-02 4:04 p.m., deadman1966@... wrote:
... Flurries and high winds here so hopefully i get a nice day in the future to get it higher in the air.
Tsk. That's not ethical, OM; right now is the time. In the ham radio
tradition procrastination in antenna work is to continue until there is
no choice by which point the weather /has/ become wet and windy!
John
at radio station VE7AOV
--
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Full set of plots for my current setup I am pretty sure they show the gypsy antenna is not that good now to find a way to improve it.
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True. It's a pretty bad antenna even at HF! When that much loss is shown
even in the first plot and progressively measures more and more as you step
upward in frequency, the loss is all there is. Especially the loss shown
at the lowest frequency with an 'average' return loss of only 5 dB (SWR of
3.6:1), most of the system is loss. The thing is about useless at 2-meters
(144 MHz)! I'd throw it out and start over, just my opinion.
Dave - W LEV
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On Wed, Nov 4, 2020 at 7:39 AM <deadman1966@...> wrote: Full set of plots for my current setup I am pretty sure they show the
gypsy antenna is not that good now to find a way to improve it.
--
*Dave - W?LEV*
*Just Let Darwin Work*
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Don't overlook the simple stuff. Disconnect the coax from the antenna and use an ohmmeter to check for shorted coax, especially if you are not really confident in your quality of connector assembly. Verify infinite resistance between the shell and center pin. Verify very low resistance (~1 ohm) between the center pins at both ends, and between the shells at both ends.
More than likely the antenna itself is OK. The info I saw shows it has a 1:1 balun, so if you can identify the ends of the windings, verify continuity of each winding and make sure there is isolation (infinite resistance) between them. Check the endpoints of the elements at the connector for shorts or opens.
The NanoVNA is a fantastic piece of gear, but it's easy to get caught up in trying to interpret the readings and overlooking fundamental tests.
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HexAndFlex
schweppe
Arie Kleingeld PA3A
