Re: where is the end fed natural resonance
Thanks for posting, Barry!
So you are discovering there really is no "end fed" resonant antenna. The
proof is in the measurements as you show. So why is this abortion so
popular??? ONLY, and ONLY because it's so easy just to throw up a wire
into the trees.....
Sure, a wire thrown up into the grees is what I typically use out camping
and boondocking, but I would never consider it for home installation where
I have the options of optimizing efficiency and fitting the HF antenna(s)
to my local environment.
Dave - W?LEV
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On Sun, Feb 25, 2024 at 7:55?PM Barry K3EUI <k3euibarry@...> wrote:
At the end of a month of testing - I conclude "there is no such thing as
a purely end-fed antenna" (hi) using UNUNs.
All end-feds using UNUNs to match impedances are really very "off-center
feds" with a counterpoise of some sort.
I wanted to see where the natural resonances occur on my new end-fed:
about 155 ft wire (#12 stranded) with 9:1 Palomar UNUN
It is fed with 100 ft RG213 coax with a choke at 90 feet from UNUN.
So perhaps it has a 90 foot "counterpoise" (whatever that means)
Here is the graph plotting RETURN LOSS (dB) and SWR from 3 to
20 MHz.
Looks like the biggest RETURN LOSS (almost 50 dB) and lowest SWR
occurs at 9.3 MHz
If we use the formula L (feet) = 468 / f (MHz) = 468 / 9.3 =
50.3 feet for a 1/2 wave length
and for the 3/2 wave resonance that gives about 151 feet (close to
my measured 155 ft)
So the formula works.
The shape of the wire is a giant horseshoe (running around my own yard)
about 20 ft high.
I am only interested in NVIS for 80m and 40m NBEMS nets (and CW).
Might I mess with the counterpoise length or the wire antenna length to
get a lower SWR on 80m and 40M?
I can live with a 2:1 SWR on 80m and 40m, or even a 3:1 SWR on the
100ft RG213 feed line, since the "added" attenuation due to higher SWR
(3:1) on 100 ft RG213
is only about 1 dB of "additional loss" on 80 meters - only a fraction
of one S-unit.
This 155 ft length is what was recommended by Palomar Engineering in
their handouts.
It can also tune up nicely on the 30m (10.1 MHz) and 20m (14.1 MHz)
and 17 meter (18.1 MHz) bands, which is great for DX
de k3eui barry
Feb 25, 2024
-- *Dave - W?LEV*
--
Dave - W?LEV
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where is the end fed natural resonance
At the end of a month of testing - I conclude "there is no such thing as a purely end-fed antenna" (hi) using UNUNs.
All end-feds using UNUNs to match impedances are really very "off-center feds" with a counterpoise of some sort.
I wanted to see where the natural resonances occur on my new end-fed: about 155 ft wire (#12 stranded) with 9:1 Palomar UNUN
It is fed with 100 ft RG213 coax with a choke at 90 feet from UNUN.
So perhaps it has a 90 foot "counterpoise" (whatever that means)
Here is the graph plotting RETURN LOSS (dB) and SWR from 3 to 20 MHz.
Looks like the biggest RETURN LOSS (almost 50 dB) and lowest SWR occurs at 9.3 MHz
If we use the formula L (feet) = 468 / f (MHz) = 468 / 9.3 = 50.3 feet for a 1/2 wave length
and for the 3/2 wave resonance that gives about 151 feet (close to my measured 155 ft)
So the formula works.
The shape of the wire is a giant horseshoe (running around my own yard) about 20 ft high.
I am only interested in NVIS for 80m and 40m NBEMS nets (and CW).
Might I mess with the counterpoise length or the wire antenna length to get a lower SWR on 80m and 40M?
I can live with a 2:1 SWR on 80m and 40m, or even a 3:1 SWR on the 100ft RG213 feed line, since the "added" attenuation due to higher SWR (3:1) on 100 ft RG213
is only about 1 dB of "additional loss" on 80 meters - only a fraction of one S-unit.
This 155 ft length is what was recommended by Palomar Engineering in their handouts.
It can also tune up nicely on the 30m (10.1 MHz) and 20m (14.1 MHz) and 17 meter (18.1 MHz) bands, which is great for DX
de k3eui barry
Feb 25, 2024
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Re: your switchable end fed transformer
Looking at the photo on their website, the switching is easy. They use a
2-turn primary and 16-turn secondary winding on the toroid. The switch
would simply take the antenna output from taps on turns 14, 15, or 16,
giving the impedance ratios of 49, 56.25, and 64:1. It appears to be a
single wire winding, making the taps easy. A simple and very nicely
implemented transformer.
A common-mode choke would be advisable on the feedline to reduce rf on the
coax shield if used with more than just a few watts qrp.
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On Sun, Feb 25, 2024, 8:55 AM Bryan Curl <bc3910@...> wrote: Hi Don,
I wonder how they switch that. it looks like an ordinary ferrite core coax
wound 1:1 balun.. I like the concept though .
Bryan, n0luf
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Re: nanoVNA-H (clone?) USB unrecognized
I'd try swapping various USB-C <> USB-A cables before cutting up a cable.
From past experience I've found some cables are not made with copper wire that you can
solder to but aluminum wire or sometimes aluminum foil strips that are crimped to the
connector pins. You might want to try an adapter like this
Or this
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Re: your switchable end fed transformer
Hi Don,
I wonder how they switch that. it looks like an ordinary ferrite core coax wound 1:1 balun.. I like the concept though .
Bryan, n0luf
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Re: final tuning of end fed 155 ft wire with 9to1 unun and tuner in shack
I have a 40m wire on a 9:1 which it mostly flat, strung between 2 30 poles, is sags a little in the middle. I had a counter poise on and it was just okay. I removed it and now have just a choke at aprox avg 1/4 wave down feed line. this is the hi current location from feed point. this antenna is awesome. Its swr is low enough [below 3:1] on 40 20 17 15 12 and 10m that the tuner in my Ic 756pro easily finishes tuning. Its better than my g5rv in that regard and hears as good or better on most bands. Its my got to antenna of all my wires.
Anyway, not disagreeing with anyone, Thats just my anecdotal experience for what its worth.
Bryan, n0luf
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Re: Nano VNA graphs of MYANTENNA end fed with 140 ft #12 wire
Peter,
Oh geez, of course you're right, I put up three antennas that day and had to move them around. I'm thinking of what started as on inverted L and ended up being a rather lazy endfed. No counterpoise. Good catch.
Andy
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Re: final tuning of end fed 155 ft wire with 9to1 unun and tuner in shack
If done properly, yes. The radiating portion should be in the clear well away from other conductors and also common-mode choked at an appropriate point. If either is not done there are problems. There are good resources on the internet that explain this. I own a Ringo. They had to add a radial kit to it to make it work right. It still doesn't work as well is it could. I suppose compared to a rubber duckie it "works great". But my Hustler G7 stomps it. 73 -Jim NU0C On Sat, 24 Feb 2024 21:42:09 -0800 "Jim Lux" <jimlux@...> wrote: Well, it is if it¡¯s designed that way. There¡¯s a whole bunch of half wave dipoles where the outer side of the feedline is half the dipole, and the center conductor is the other half. ¡°Sleeve dipoles¡± are one version. The Ringo Ranger is one version.
But yeah, there are many potential traps for the unwary in such designs. Good chokes to limit just where the coax is being used as a radiator might be useful.
On Feb 24, 2024, at 9:32?PM, Jim Shorney <jimNU0C@...> wrote:
?
It should be mentioned that using your coax as the counterpoise is not best practice.
73
-Jim
NU0C
On Sat, 24 Feb 2024 18:25:40 -0500
"Barry K3EUI" <k3euibarry@...> wrote:
*I've had a MyANTENNA 130 ft end fed 1/2 wave with 49:1 UNUN up
for one week and it works but is very "touchy" to tune up around 3580 kHz*
*I took it down, added wire, and set up a Palomar 9:1 UNUN and now
have a _non-resonant wire length of 155 ft_ for 80m*
*Feed line is 100 ft RG213 with a RF choke at 95 ft from UNUN, so
a 95 ft "counterpoise" using the coax shield.*
*This is my final adjustment using an Ameritron AT-20 manual T network
tuner in the shack
*
*Tuned up for lowest SWR around 3580 kHz for NBEMS nets on weekends*
*Return Loss about _27 dB_ at resonance, as shown.
*
*
*
*Let's see how it compares to a standard 1/2 wave 130 ft center fed
dipole with 1:1 BALUN*
*
*
*de k3eui barry*
*==========================*
--
73
-Jim
NU0C
-- 73 -Jim NU0C
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Re: final tuning of end fed 155 ft wire with 9to1 unun and tuner in shack
Well, it is if it¡¯s designed that way. There¡¯s a whole bunch of half wave dipoles where the outer side of the feedline is half the dipole, and the center conductor is the other half. ¡°Sleeve dipoles¡± are one version. The Ringo Ranger is one version.
But yeah, there are many potential traps for the unwary in such designs. Good chokes to limit just where the coax is being used as a radiator might be useful.
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On Feb 24, 2024, at 9:32?PM, Jim Shorney <jimNU0C@...> wrote:
?
It should be mentioned that using your coax as the counterpoise is not best practice.
73
-Jim
NU0C
On Sat, 24 Feb 2024 18:25:40 -0500
"Barry K3EUI" <k3euibarry@...> wrote:
*I've had a MyANTENNA 130 ft end fed 1/2 wave with 49:1 UNUN up
for one week and it works but is very "touchy" to tune up around 3580 kHz*
*I took it down, added wire, and set up a Palomar 9:1 UNUN and now
have a _non-resonant wire length of 155 ft_ for 80m*
*Feed line is 100 ft RG213 with a RF choke at 95 ft from UNUN, so
a 95 ft "counterpoise" using the coax shield.*
*This is my final adjustment using an Ameritron AT-20 manual T network
tuner in the shack
*
*Tuned up for lowest SWR around 3580 kHz for NBEMS nets on weekends*
*Return Loss about _27 dB_ at resonance, as shown.
*
*
*
*Let's see how it compares to a standard 1/2 wave 130 ft center fed
dipole with 1:1 BALUN*
*
*
*de k3eui barry*
*==========================*
--
73
-Jim
NU0C
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Re: final tuning of end fed 155 ft wire with 9to1 unun and tuner in shack
It should be mentioned that using your coax as the counterpoise is not best practice. 73 -Jim NU0C On Sat, 24 Feb 2024 18:25:40 -0500 "Barry K3EUI" <k3euibarry@...> wrote: *I've had a? MyANTENNA? 130 ft? end fed ? 1/2 wave? with?? 49:1 UNUN? up
for one week and it works but is very "touchy" to tune up around 3580 kHz*
*I took it down, added wire, and set up a Palomar? 9:1 UNUN?? and now
have a _non-resonant wire length of 155 ft_? for 80m*
*Feed line is 100 ft?? RG213? with a? RF choke at 95 ft from? UNUN, so
a? 95 ft "counterpoise" using the coax shield.*
*This is my final adjustment using an Ameritron AT-20 manual T network
tuner in the shack
*
*Tuned up for lowest SWR around 3580 kHz for NBEMS nets on weekends*
*Return Loss about _27 dB_?? at resonance, as shown.
*
*
*
*Let's see how it compares to a standard 1/2 wave 130 ft? center fed
dipole with 1:1 BALUN*
*
*
*de k3eui barry*
*==========================*
-- 73 -Jim NU0C
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Re: final tuning of end fed 155 ft wire with 9to1 unun and tuner in shack
I use the MyAntenna 10-75-2Kw in an inverted L, 50ft LMR-400, 30ft rise, then 100ft horizontal at about 30ft. Works great.
73, Brian
W1BKW
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-----Original Message----- From: [email protected] < [email protected]> On Behalf Of Barry K3EUI Sent: Saturday, February 24, 2024 18:26 To: Barry Feierman <k3euibarry@...> Subject: [nanovna-users] final tuning of end fed 155 ft wire with 9to1 unun and tuner in shack *I've had a? MyANTENNA? 130 ft? end fed ? 1/2 wave? with?? 49:1 UNUN? up for one week and it works but is very "touchy" to tune up around 3580 kHz* *I took it down, added wire, and set up a Palomar? 9:1 UNUN?? and now have a _non-resonant wire length of 155 ft_? for 80m* *Feed line is 100 ft?? RG213? with a? RF choke at 95 ft from? UNUN, so a? 95 ft "counterpoise" using the coax shield.* *This is my final adjustment using an Ameritron AT-20 manual T network tuner in the shack * *Tuned up for lowest SWR around 3580 kHz for NBEMS nets on weekends* *Return Loss about _27 dB_?? at resonance, as shown. * * * *Let's see how it compares to a standard 1/2 wave 130 ft? center fed dipole with 1:1 BALUN* * * *de k3eui barry* *==========================*
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final tuning of end fed 155 ft wire with 9to1 unun and tuner in shack
*I've had a? MyANTENNA? 130 ft? end fed ? 1/2 wave? with?? 49:1 UNUN? up for one week and it works but is very "touchy" to tune up around 3580 kHz*
*I took it down, added wire, and set up a Palomar? 9:1 UNUN?? and now have a _non-resonant wire length of 155 ft_? for 80m*
*Feed line is 100 ft?? RG213? with a? RF choke at 95 ft from? UNUN, so a? 95 ft "counterpoise" using the coax shield.*
*This is my final adjustment using an Ameritron AT-20 manual T network tuner in the shack
*
*Tuned up for lowest SWR around 3580 kHz for NBEMS nets on weekends*
*Return Loss about _27 dB_?? at resonance, as shown.
*
*
*
*Let's see how it compares to a standard 1/2 wave 130 ft? center fed dipole with 1:1 BALUN*
*
*
*de k3eui barry*
*==========================*
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Re: Nano VNA graphs of MYANTENNA end fed with 140 ft #12 wire
What is a premium core? An inverted-L typically has a impedance <50 ohms and a endfed halfwave is high impedance, so neither a 1:9 nor a 1:4 transformer could be right. 73 Peter, DJ7WW -----Original-Nachricht----- Von: "Andrew Harman" <Nexus9d9@...> An: " [email protected]" < [email protected]> Back to EFHW, a couple of years ago I played with inverted "L"s. As I previously stated I first used a 9:1 and found the core to be garbage giving me both poor band coverage and extremely high SWR. I had a few 4:1 Balun Designs transformers kicking around and rewound one as a 9:1, beautiful results because they use a premium core. But I relocated that for Field Day and It wasn't as impressive (soils again?). Another ham there loaned me a 49:1 with better results. So as they say, "individual results may vary". Andy ?
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Re: Nano VNA graphs of MYANTENNA end fed with 140 ft #12 wire
On Fri, Feb 23, 2024 at 09:33 AM, N2MS wrote:
I consider these EFHW designs another example of broadband lossy designs such
as the Tilted Terminated Folded Dipole T2FD antenna which uses a resistive
termination. One could follow a trick used by Barker and Williamson in the
design of their T2FD by using stainless steel wire. The higher resistance of
the steel wire would also result in a lower SWR at the expense of efficiency.
I've used them before - great company. In my application and if I remember the part number correctly it was the BWDS1.5-80 with the stainless steel wire. I had that installed as a backup to a CMV-604 vertical for a KC-135 mission east of Halifax from Niagara Falls. It was mounted in a horizontal dipole configuration at 35 ft. The stainless steel wire model was chosen for strength and durability in icy and high wind conditions. Mind you this was a dipole. The SWR was very low and almost perfect in fact. During operational testing, unexpectedly, Minot ND had to ask us to turn down our power. Moving antennas to different locations over the years I was in Combat Comm we learned that the soil conditions do play in a large part. The same antenna was unpredictable over a thin soil, high rock or heavy clays. Having a switchable transformer as was mentioned would have been sweet for us or even having an assortment to play with. Testing the antenna Z (without its transformer) in each specific installation would be the most ideal however when elevated could be impractical. Back to EFHW, a couple of years ago I played with inverted "L"s. As I previously stated I first used a 9:1 and found the core to be garbage giving me both poor band coverage and extremely high SWR. I had a few 4:1 Balun Designs transformers kicking around and rewound one as a 9:1, beautiful results because they use a premium core. But I relocated that for Field Day and It wasn't as impressive (soils again?). Another ham there loaned me a 49:1 with better results. So as they say, "individual results may vary". Andy
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Re: Nano VNA graphs of MYANTENNA end fed with 140 ft #12 wire
I just substituted a 9:1 Palomar Engineering UNUN with 100 ftRG213 (counterpoise) and changed the wire length to 155 ft in a large horizontal loop (around my back yard).
Everything looks better than the 49:1 UNUN and 130 ft wire on 80m and 40m, but we will test more thoroughly
de k3eui barry
Phila PA
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Re: your switchable end fed transformer
Just received it, no on-air results yet, but the build quality seems excellent.
Hint: If you want to add more/different counterpoises or radiators without soldering you will need to buy 2mm mini banana plugs which fit the receptacles:
73, Don N2VGU
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Re: MODIFIED END FED 155 FT AND 9 TO 1 UNUN
Preferably look at the Smith. The phase jump is only a graphical effect of the fact that the phase passes beyond 180¡ã then below. On the Smith the curve will be continuous.
--
F1AMM
Fran?ois
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Re: MODIFIED END FED 155 FT AND 9 TO 1 UNUN
It¡¯s like something make a second resonant point but not a real resonant point as other graphs don¡¯t show it.
Did you try to make the same mesurement without the tuner ?
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your switchable end fed transformer
Did you build, or purchase? if the latter, where did you get it?
Thanks for the information.
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On Feb 23, 2024, at 8:55 AM, Donald S Brant Jr <dsbrantjr@...> wrote:
I have an end-fed antenna with switch-selectable 49, 56 and 64:1 ratios. It's covered with heat shrink so I haven't looked inside. Checks out OK with VNA.
73, Don N2VGU
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Re: nanoVNA-H (clone?) USB unrecognized
Hello Dennis & Tim!
Thanks for the reply and ideeas.
From what you said, it seems that I have no other solutions but to try several versions of firmware swapped with various USB-C <> USB-A cables taken in order.
Another option I am thinking of, would be to try to cut such a cable and directly solder the Vcc / D+ / D- / GND terminals to the existing pins on the nanoVNA PCB (VBUS / USB_DM / USB_DP / GND). I have numbered them in order on the attached diagram (1 / 2 / 3 / 4).
What do you think ?
Thank you!
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Barry K3EUI
Jim Shorney
Brian Wall
Donald S Brant Jr
Bobinuta Bobinel
