|
*
*
*
*
*latest update de k3eui Barry END-FED wire extension to 140 feet*
*
*
*new QTH: Kennett Square PA (SW of Phila)*
*
*
*I waited for a cooler day to extend my 70 ft end-fed (worked well on 40/20m) out to the full length of _140 feet_.*
*It is fed via a 49:1 UNUN (MyAntenna) with a 33 ft counterpoise, with 50 ft of RG8X.*
*RF Choke before coax enters the shack for RFI prevention.
*
*
*
*My goal: be able to use this on three bands: 160/80/40 in the digi part of each band.*
*So I left it a bit "long" at about _140 ft_ (most cut this to 130-135 ft for phone part of bands)*
*
*
*I am ready to try this out on the Sunday NBEMS nets:*
* PaNBEMS at 0730 hr on 3583 kHz (Thor 22)*
* NJNBEMS at 0900 hr on 3582 kHz (Thor 22)*
*
*
*It is oriented East-West but low to the ground, so likely has no directional gain/loss.*
*We'll see tomorrow morning.*
*
*
*Here is the Nano VNA plot of SWR and Return Loss dB (plotted as a negative value)*
*SWR is below 2:1 where I will operate with sound card modes.*
*Looks like I might be able to improve it just a bit by cutting 1 to 2 ft off the far end.*
*
*
*note: Return Loss about /_-3 dB_/ where the antenna is /_not_/ a multiple 1/2 wave (resonant)
*
*which may show UNUN loss or coax loss - but I'm not worried about this loss on these bands.
*
*
*
*de k3eui*
*July 20*
|
Has anyone ever measured the loss through a pair of 49:1 UNUNs
connected back to back?
73
Frank
W3LPL
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----- Original Message -----
From: "Barry K3EUI" <k3euibarry@...>
To: "Barry Feierman" <k3euibarry@...>
Sent: Saturday, July 20, 2024 9:50:44 AM
Subject: [nanovna-users] 140 ft end fed looks decent on 3 lower hf bands for digi
*
*
*
*
*latest update de k3eui Barry END-FED wire extension to 140 feet*
*
*
*new QTH: Kennett Square PA (SW of Phila)*
*
*
*I waited for a cooler day to extend my 70 ft end-fed (worked well on
40/20m) out to the full length of _140 feet_.*
*It is fed via a 49:1 UNUN (MyAntenna) with a 33 ft counterpoise, with
50 ft of RG8X.*
*RF Choke before coax enters the shack for RFI prevention.
*
*
*
*My goal: be able to use this on three bands: 160/80/40 in the digi part
of each band.*
*So I left it a bit "long" at about _140 ft_ (most cut this to 130-135
ft for phone part of bands)*
*
*
*I am ready to try this out on the Sunday NBEMS nets:*
* PaNBEMS at 0730 hr on 3583 kHz (Thor 22)*
* NJNBEMS at 0900 hr on 3582 kHz (Thor 22)*
*
*
*It is oriented East-West but low to the ground, so likely has no
directional gain/loss.*
*We'll see tomorrow morning.*
*
*
*Here is the Nano VNA plot of SWR and Return Loss dB (plotted as a
negative value)*
*SWR is below 2:1 where I will operate with sound card modes.*
*Looks like I might be able to improve it just a bit by cutting 1 to 2
ft off the far end.*
*
*
*note: Return Loss about /_-3 dB_/ where the antenna is /_not_/ a
multiple 1/2 wave (resonant)
*
*which may show UNUN loss or coax loss - but I'm not worried about this
loss on these bands.
*
*
*
*de k3eui*
*July 20*
|
seems to be a bit long when looking your swr sweeps
dg9bfc sigi
Am 20.07.2024 um 18:50 schrieb Barry K3EUI:
переключити цитоване повідомлення
Показати цитований текст
*
*
*
*
*latest update de k3eui Barry END-FED wire extension to 140 feet*
*
*
*new QTH: Kennett Square PA (SW of Phila)*
*
*
*I waited for a cooler day to extend my 70 ft end-fed (worked well on 40/20m) out to the full length of _140 feet_.*
*It is fed via a 49:1 UNUN (MyAntenna) with a 33 ft counterpoise, with 50 ft of RG8X.*
*RF Choke before coax enters the shack for RFI prevention.
*
*
*
*My goal: be able to use this on three bands: 160/80/40 in the digi part of each band.*
*So I left it a bit "long" at about _140 ft_ (most cut this to 130-135 ft for phone part of bands)*
*
*
*I am ready to try this out on the Sunday NBEMS nets:*
* PaNBEMS at 0730 hr on 3583 kHz (Thor 22)*
* NJNBEMS at 0900 hr on 3582 kHz (Thor 22)*
*
*
*It is oriented East-West but low to the ground, so likely has no directional gain/loss.*
*We'll see tomorrow morning.*
*
*
*Here is the Nano VNA plot of SWR and Return Loss dB (plotted as a negative value)*
*SWR is below 2:1 where I will operate with sound card modes.*
*Looks like I might be able to improve it just a bit by cutting 1 to 2 ft off the far end.*
*
*
*note: Return Loss about /_-3 dB_/ where the antenna is /_not_/ a multiple 1/2 wave (resonant)
*
*which may show UNUN loss or coax loss - but I'm not worried about this loss on these bands.
*
*
*
*de k3eui*
*July 20*
|
|
|
Thanks Russ,
W0LEV has a much better idea than mine: measure the RF current at the
center of a half wave end fed antenna. Then compare the measured
current to the RF current at the center of a center fed half wave dipole
73
Frank
W3LPL
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Показати цитований текст
----- Original Message ----- From: "va3rr via groups.io" <va3rr@...> To: nanovna-users@groups.io Sent: Saturday, July 20, 2024 10:17:50 AM Subject: Re: [nanovna-users] 140 ft end fed looks decent on 3 lower hf bands for digi There's a fairly lengthy thread on QRZ regarding back-to-back insertion loss measurement vs resistive. https://forums.qrz.com/index.php?threads/49-1-transformer-losses.862131/page-573 de Russ, va3rr On Sat, Jul 20, 2024 at 12:54 PM, Frank Donovan wrote: Has anyone ever measured the loss through a pair of 49:1 UNUNs
connected back to back?
|
Let us know what you use and how you measured the RF current.
A black art, seldom done, often with dubious results.
Ed McCann
AG6CX
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On Jul 20, 2024, at 10:32 AM, Frank Donovan via groups.io <donovanf@...> wrote:
Thanks Russ,
W0LEV has a much better idea than mine: measure the RF current at the
center of a half wave end fed antenna. Then compare the measured
current to the RF current at the center of a center fed half wave dipole
73
Frank
W3LPL
----- Original Message -----
From: "va3rr via groups.io" <va3rr@...>
To: nanovna-users@groups.io
Sent: Saturday, July 20, 2024 10:17:50 AM
Subject: Re: [nanovna-users] 140 ft end fed looks decent on 3 lower hf bands for digi
There's a fairly lengthy thread on QRZ regarding back-to-back insertion loss measurement vs resistive.
https://forums.qrz.com/index.php?threads/49-1-transformer-losses.862131/page-5
73 de Russ, va3rr
On Sat, Jul 20, 2024 at 12:54 PM, Frank Donovan wrote:
Has anyone ever measured the loss through a pair of 49:1 UNUNs
connected back to back?
|
How do you find this thread referenced above in QRZ? 49-1-transformer-losses.862131/page-5 < https://forums.qrz.com/index.php?threads/49-1-transformer-losses.862131/page-5> Fred N4CLA On Sat, Jul 20, 2024 at 1:50 PM AG6CX via groups.io <edwmccann= gmail.com@groups.io> wrote: Let us know what you use and how you measured the RF current.
A black art, seldom done, often with dubious results.
Ed McCann
AG6CX
On Jul 20, 2024, at 10:32 AM, Frank Donovan via groups.io <donovanf= starpower.net@groups.io> wrote:
Thanks Russ,
W0LEV has a much better idea than mine: measure the RF current at the
center of a half wave end fed antenna. Then compare the measured
current to the RF current at the center of a center fed half wave dipole
73
Frank
W3LPL
----- Original Message -----
From: "va3rr via groups.io" <va3rr@...>
To: nanovna-users@groups.io
Sent: Saturday, July 20, 2024 10:17:50 AM
Subject: Re: [nanovna-users] 140 ft end fed looks decent on 3 lower hf
bands for digi
There's a fairly lengthy thread on QRZ regarding back-to-back insertion
loss measurement vs resistive.
https://forums.qrz.com/index.php?threads/49-1-transformer-losses.862131/page-5
73 de Russ, va3rr
On Sat, Jul 20, 2024 at 12:54 PM, Frank Donovan wrote:
Has anyone ever measured the loss through a pair of 49:1 UNUNs
connected back to back?
|
|
|
I couldn't resist modeling your EF wire, especially since you reported a low SWR point just below the 160-meter band for the 140-footer horizontal wire. This should not be there with a 140-foot long horizontal wire. So, I also modeled a 270-foot long wire. Please have a read of the attachment for the results. Dave - WØLEV On Sat, Jul 20, 2024 at 4:51 PM Barry K3EUI via groups.io <k3euibarry= gmail.com@groups.io> wrote: *
*
*
*
*latest update de k3eui Barry END-FED wire extension to 140 feet*
*
*
*new QTH: Kennett Square PA (SW of Phila)*
*
*
*I waited for a cooler day to extend my 70 ft end-fed (worked well on
40/20m) out to the full length of _140 feet_.*
*It is fed via a 49:1 UNUN (MyAntenna) with a 33 ft counterpoise, with
50 ft of RG8X.*
*RF Choke before coax enters the shack for RFI prevention.
*
*
*
*My goal: be able to use this on three bands: 160/80/40 in the digi part
of each band.*
*So I left it a bit "long" at about _140 ft_ (most cut this to 130-135
ft for phone part of bands)*
*
*
*I am ready to try this out on the Sunday NBEMS nets:*
* PaNBEMS at 0730 hr on 3583 kHz (Thor 22)*
* NJNBEMS at 0900 hr on 3582 kHz (Thor 22)*
*
*
*It is oriented East-West but low to the ground, so likely has no
directional gain/loss.*
*We'll see tomorrow morning.*
*
*
*Here is the Nano VNA plot of SWR and Return Loss dB (plotted as a
negative value)*
*SWR is below 2:1 where I will operate with sound card modes.*
*Looks like I might be able to improve it just a bit by cutting 1 to 2
ft off the far end.*
*
*
*note: Return Loss about /_-3 dB_/ where the antenna is /_not_/ a
multiple 1/2 wave (resonant)
*
*which may show UNUN loss or coax loss - but I'm not worried about this
loss on these bands.
*
*
*
*de k3eui*
*July 20*
-- *Dave - WØLEV* -- Dave - WØLEV
|
I have no explanation for why the 140 ft "end-fed" with MyAntenna 49:1 UNUN has a dip on the 160m band.
I've never operated on 160m, but I won't complain if the antenna works there.
But I know it is 140 ft and not 270 ft long.
There is no way I can (easily) measure currents anywhere along the radiating wire!!
But if it works (well enough for me) on 80m and 40m for NVIS NBEMS regional (east coast) nets, that is acceptable.
I did not plan on using it on 20m, 15m, or 10m, but I won't complain if it works well there too.
Dave - TU once again for all of your wisdom and suggestions.
I'm trying it out today on two NBEMS 80m nets (Pa and NJ) on 3583 kHz
de k3eui barry
near Philly PA
|
I just realized if I include the cable and adapter, I will need a set of standards for PL259. 73 Ken On Sun, Jul 21, 2024 at 8:01 AM Barry K3EUI via groups.io <k3euibarry= gmail.com@groups.io> wrote: I have no explanation for why the 140 ft "end-fed" with MyAntenna 49:1
UNUN has a dip on the 160m band.
I've never operated on 160m, but I won't complain if the antenna works
there.
But I know it is 140 ft and not 270 ft long.
There is no way I can (easily) measure currents anywhere along the
radiating wire!!
But if it works (well enough for me) on 80m and 40m for NVIS NBEMS
regional (east coast) nets, that is acceptable.
I did not plan on using it on 20m, 15m, or 10m, but I won't complain if it
works well there too.
Dave - TU once again for all of your wisdom and suggestions.
I'm trying it out today on two NBEMS 80m nets (Pa and NJ) on 3583 kHz
de k3eui barry
near Philly PA
|
I note the 140 ft end fed is a quarter-wave on 160. Maybe it thinks it’s a vertical?
My 135 ft dipole fed with 70 ft of 450 ohm ladder line offers a low Rs resonance at 1/8 wave. Tie both ends of ladder at shack to tuner for occasional winter 160 use.
Ed McCann
AG6CX
Sausalito CA
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On Jul 21, 2024, at 5:01 AM, Barry K3EUI via groups.io <k3euibarry@...> wrote:
I have no explanation for why the 140 ft "end-fed" with MyAntenna 49:1 UNUN has a dip on the 160m band.
I've never operated on 160m, but I won't complain if the antenna works there.
But I know it is 140 ft and not 270 ft long.
There is no way I can (easily) measure currents anywhere along the radiating wire!!
But if it works (well enough for me) on 80m and 40m for NVIS NBEMS regional (east coast) nets, that is acceptable.
I did not plan on using it on 20m, 15m, or 10m, but I won't complain if it works well there too.
Dave - TU once again for all of your wisdom and suggestions.
I'm trying it out today on two NBEMS 80m nets (Pa and NJ) on 3583 kHz
de k3eui barry
near Philly PA
|
At <30 MHz, this is easy - open is just “no connector”, A short is easy to make. There are tons of 50 ohm dummy loads with a SO-239, or you can get a non-inductive 50 ohm resistor from Caddock and solder it to a SO-239.
Sure, if you get a cheap dummy load the load might be a few cm from the mating reference surface of the connector (wherever that’s defined), but the error is tiny.
I modified a RCS-8V antenna switch to make what’s effectively a remote controllable calibration reference.
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On Jul 21, 2024, at 7:52 AM, Ken <chase8043@...> wrote:
I just realized if I include the cable and adapter, I will need a set of
standards for PL259.
73 Ken
On Sun, Jul 21, 2024 at 8:01 AM Barry K3EUI via groups.io <k3euibarry=
gmail.com@groups.io> wrote:
I have no explanation for why the 140 ft "end-fed" with MyAntenna 49:1
UNUN has a dip on the 160m band.
I've never operated on 160m, but I won't complain if the antenna works
there.
But I know it is 140 ft and not 270 ft long.
There is no way I can (easily) measure currents anywhere along the
radiating wire!!
But if it works (well enough for me) on 80m and 40m for NVIS NBEMS
regional (east coast) nets, that is acceptable.
I did not plan on using it on 20m, 15m, or 10m, but I won't complain if it
works well there too.
Dave - TU once again for all of your wisdom and suggestions.
I'm trying it out today on two NBEMS 80m nets (Pa and NJ) on 3583 kHz
de k3eui barry
near Philly PA
|
just a guess the antenna "thinks" it is a quarterwave (and maybe uses your coax as other half??)
dg9bfc sigi
Am 21.07.2024 um 14:01 schrieb Barry K3EUI:
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Показати цитований текст
I have no explanation for why the 140 ft "end-fed" with MyAntenna 49:1 UNUN has a dip on the 160m band.
I've never operated on 160m, but I won't complain if the antenna works there.
But I know it is 140 ft and not 270 ft long.
There is no way I can (easily) measure currents anywhere along the radiating wire!!
But if it works (well enough for me) on 80m and 40m for NVIS NBEMS regional (east coast) nets, that is acceptable.
I did not plan on using it on 20m, 15m, or 10m, but I won't complain if it works well there too.
Dave - TU once again for all of your wisdom and suggestions.
I'm trying it out today on two NBEMS 80m nets (Pa and NJ) on 3583 kHz
de k3eui barry
near Philly PA
|
That would have to be a coax cable run of some 130-feet in itself. No doubt just an UNUN / autotransformer at the feed (the 50-ohm side of the 49:1 UNUN) will not isolate the outer surface of the coax in participating in radiation. So, how long is the coax run from the 50-ohm port of the 49:1 UNUN / autotransformer to the ham shack? Dave - WØLEV On Sun, Jul 21, 2024 at 7:02 PM Siegfried Jackstien via groups.io <siegfried.jackstien@...> wrote: just a guess the antenna "thinks" it is a quarterwave (and maybe uses
your coax as other half??)
dg9bfc sigi
Am 21.07.2024 um 14:01 schrieb Barry K3EUI:
I have no explanation for why the 140 ft "end-fed" with MyAntenna 49:1 UNUN has a dip on the 160m band.
I've never operated on 160m, but I won't complain if the antenna works there.
But I know it is 140 ft and not 270 ft long.
There is no way I can (easily) measure currents anywhere along the radiating wire!!
But if it works (well enough for me) on 80m and 40m for NVIS NBEMS
regional (east coast) nets, that is acceptable.
I did not plan on using it on 20m, 15m, or 10m, but I won't complain if it works well there too.
Dave - TU once again for all of your wisdom and suggestions.
I'm trying it out today on two NBEMS 80m nets (Pa and NJ) on 3583 kHz
de k3eui barry
near Philly PA
-- *Dave - WØLEV* -- Dave - WØLEV
|
Not necessarily 130 feet.
Could be as little as 70 feet (20 meters or so) and present itself as a 1/8 wavelength, low radiation resistance, low impedance, and with sufficient CMC radiate from the coax as a top-loaded vertical.
73,
Ed McCann
AG6CX
Sausalito CA
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On Jul 21, 2024, at 12:47 PM, W0LEV via groups.io <davearea51a@...> wrote:
That would have to be a coax cable run of some 130-feet in itself. No
doubt just an UNUN / autotransformer at the feed (the 50-ohm side of the
49:1 UNUN) will not isolate the outer surface of the coax in participating
in radiation.
So, how long is the coax run from the 50-ohm port of the 49:1 UNUN /
autotransformer to the ham shack?
Dave - WØLEV
On Sun, Jul 21, 2024 at 7:02 PM Siegfried Jackstien via groups.io
<siegfried.jackstien@...> wrote:
just a guess the antenna "thinks" it is a quarterwave (and maybe uses
your coax as other half??)
dg9bfc sigi
Am 21.07.2024 um 14:01 schrieb Barry K3EUI:
I have no explanation for why the 140 ft "end-fed" with MyAntenna 49:1 UNUN has a dip on the 160m band.
I've never operated on 160m, but I won't complain if the antenna works there.
But I know it is 140 ft and not 270 ft long.
There is no way I can (easily) measure currents anywhere along the radiating wire!!
But if it works (well enough for me) on 80m and 40m for NVIS NBEMS
regional (east coast) nets, that is acceptable.
I did not plan on using it on 20m, 15m, or 10m, but I won't complain if it works well there too.
Dave - TU once again for all of your wisdom and suggestions.
I'm trying it out today on two NBEMS 80m nets (Pa and NJ) on 3583 kHz
de k3eui barry
near Philly PA
--
*Dave - WØLEV*
--
Dave - WØLEV
|
Not necessarily 130 feet.
Could be as little as 70 feet (20 meters or so) and present itself as a 1/8 wavelength, low radiation resistance, low impedance, and with sufficient CMC radiate from the coax as a top-loaded vertical.
73,
Ed McCann
AG6CX
Sausalito CA
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Показати цитований текст
On Jul 21, 2024, at 12:47 PM, W0LEV via groups.io <davearea51a@...> wrote:
That would have to be a coax cable run of some 130-feet in itself. No
doubt just an UNUN / autotransformer at the feed (the 50-ohm side of the
49:1 UNUN) will not isolate the outer surface of the coax in participating
in radiation.
So, how long is the coax run from the 50-ohm port of the 49:1 UNUN /
autotransformer to the ham shack?
Dave - WØLEV
On Sun, Jul 21, 2024 at 7:02 PM Siegfried Jackstien via groups.io
<siegfried.jackstien@...> wrote:
just a guess the antenna "thinks" it is a quarterwave (and maybe uses
your coax as other half??)
dg9bfc sigi
Am 21.07.2024 um 14:01 schrieb Barry K3EUI:
I have no explanation for why the 140 ft "end-fed" with MyAntenna 49:1 UNUN has a dip on the 160m band.
I've never operated on 160m, but I won't complain if the antenna works there.
But I know it is 140 ft and not 270 ft long.
There is no way I can (easily) measure currents anywhere along the radiating wire!!
But if it works (well enough for me) on 80m and 40m for NVIS NBEMS regional (east coast) nets, that is acceptable.
I did not plan on using it on 20m, 15m, or 10m, but I won't complain if it works well there too.
Dave - TU once again for all of your wisdom and suggestions.
I'm trying it out today on two NBEMS 80m nets (Pa and NJ) on 3583 kHz
de k3eui barry
near Philly PA --
*Dave - WØLEV*
--
Dave - WØLEV
|
On Sun, Jul 21, 2024 at 08:01 AM, Barry K3EUI wrote:
I have no explanation for why the 140 ft "end-fed" with MyAntenna 49:1 UNUN
has a dip on the 160m band.
I've never operated on 160m, but I won't complain if the antenna works there.
Consider checking for an unexpected resonance in your balun or choke, which might overheat if operated in a resonant condition. This has happened to folks who tried running old non-WARC tube amplifiers on WARC bands, unaware of plate choke resonances in those bands they burnt out the chokes. You might want to try running at moderate power and see if anything gets hot. I have an 80/40 trapped/loaded dipole which shows a resonance in the 60 meter band. Nothing gets hot at the power levels I use on that band so it is not an issue. 73, Don N2VGU
|
Barry K3EUI
va3rr
Donald S Brant Jr