Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Erik Basilier]

Hi Frank,

 

I am not giving up on WSPRLite, but after I used EZNEC to look at  interactions 
last night, I will probably have to find a roomier antenna range than my own 
back yard.

 

I agree that it would be nice to move discussion about WSPRLite to somewhere 
else. I do sometimes look at the WSPRLite Facebook group, but I don’t like it, 
partly because I dislike the whole concept of Facebook, and partly because I 
don’t like the cluttery interface that makes it slow to use. I like yahoo 
groups better, even though there is a lot to criticize about the interface for 
those.

 

To those following this discussion in the Elecraft list, I want to apologize 
for the lack of formatting of my latest, very long post (and some earlier 
posts). I just haven’t learnt how to write a post in a proper editor and then 
transfer the content to a post while preserving the formatting. Any suggestions 
would be appreciated. Maybe there is some generic advice somewhere for all 
Nabble lists? In this short post I am separating paragraphs by return 
characters so that I see a single blank line between paragraphs. I am afraid 
that when you receive this, you will see too much space between paragraphs.

 

Also for the Elecrafters that don’t already know the WSPRLite concepts, I want 
to explain that when Frank refers to DXPlorer, that is the actual trade name 
for the proprietary software that takes the free WSPR data and creates from it 
a single performance number for each transmission. (That is also the number 
graphed together with the number from the other transmitter/antenna used for 
comparison.  In my previous posts I wanted to limit the post length by not 
mentioning the DXPlorer name. 

 

73,

Erik K7TV

 

From: donov...@starpower.net [mailto:donov...@starpower.net] 
Sent: Wednesday, November 22, 2017 10:42 AM
To: elecraft@mailman.qth.net
Cc: donw...@embarqmail.com; Erik Basilier <ebasil...@cox.net>
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30

 

Hi Eric,

 

Don't give up on WSPRlite, with experience you'll learn that its an

exceptionally powerful antenna evaluation tool.

 

The "simultaneous spots" comparison tool on DXplorer.net allows you

to select the maximum distance for the WSPR reports being evaluated. 

It also computes the mean and standard deviations in dB between the

two WSPRlite transmitters (and antennas) being compared.   There's

no magic here.

 

Because the ionosphere and your antennas are the media connecting

your WSPRlite transmitters to WSPR receivers all over the world,

its very important that you take steps to reduce interaction

among the antennas being compared and to reduce the ionospheric

variability affecting usefulness the reported data.  The important

necessary steps are:

 

1. The antennas should transmit the same polarization.

 

2. The antennas should be as close as possible but not so close that

they interact with each other (EZNEC helps you reduce interactions)

 

This discussion needs to move off of the Elecraft reflector, it has little

to do with the purpose of this reflector or Elecraft products  The

WSPRlite page on Facebook is a better choice.

 

73

Frank

W3LPL

 

  _  

From: "Erik Basilier" <ebasil...@cox.net <mailto:ebasil...@cox.net> >
To: donw...@embarqmail.com <mailto:donw...@embarqmail.com> , 
donov...@starpower.net <mailto:donov...@starpower.net> , 
elecraft@mailman.qth.net <mailto:elecraft@mailman.qth.net> 
Sent: Wednesday, November 22, 2017 8:43:57 AM
Subject: RE: [Elecraft] KX3 Field Ant. for 80/40/30

Don, please see my comments below:

>About all you can conclude from the WSPR readings is the relative difference 
>between antennas.  If you want to compare two horizontal antennas, place them 
>end to end.  >The radiation at the end is at a minimum and the antenna will 
>not interact.

Years ago I was under the naïve impression that if you buy a perfectly 
symmetrical GP, put it in a vertical position high up in the air, with no 
nearby metal objects, and run the coax perfectly vertically to a transmitter 
where the feeder hits the ground, you will get a nice pattern that is well 
predicted by a model. After all, the antenna manufacturer probably showed us 
that pattern in their catalog, and we have seen that pattern before in our 
antenna book. Well, not too long ago QST published an article that said 
(paraphrasing): "Not so fast. Sometimes you will get a very different pattern, 
and it may be terrible at the low elevation angles that you want." The reason: 
the feedline has current on the outside. How much will depend on its length. 
Putting a common mode choke at the feedpoint won't save you if the feedline is 
long; you may have to break up the current by several chokes along the line." 
The author supported this by theory as well as measurement. And why not? The 
feedline is a nearby metallic object, so why should it not affect the 

Re: [Elecraft] KX3 Field Ant. for 80/40/30

[donovanf]

Hi Eric, 


Don't give up on WSPRlite, with experience you'll learn that its an 
exceptionally powerful antenna evaluation tool. 


The "simultaneous spots" comparison tool on DXplorer.net allows you 
to select the maximum distance for the WSPR reports being evaluated. 
It also computes the mean and standard deviations in dB between the 
two WSPRlite transmitters (and antennas) being compared. There's 
no magic here. 


Because the ionosphere and your antennas are the media connecting 
your WSPRlite transmitters to WSPR receivers all over the world, 
its very important that you take steps to reduce interaction 
among the antennas being compared and to reduce the ionospheric 
variability affecting usefulness the reported data. The important 
necessary steps are: 


1. The antennas should transmit the same polarization. 


2. The antennas should be as close as possible but not so close that 
they interact with each other (EZNEC helps you reduce interactions) 


This discussion needs to move off of the Elecraft reflector, it has little 
to do with the purpose of this reflector or Elecraft products The 
WSPRlite page on Facebook is a better choice. 


73 
Frank 
W3LPL 

- Original Message -

From: "Erik Basilier" <ebasil...@cox.net> 
To: donw...@embarqmail.com, donov...@starpower.net, elecraft@mailman.qth.net 
Sent: Wednesday, November 22, 2017 8:43:57 AM 
Subject: RE: [Elecraft] KX3 Field Ant. for 80/40/30 

Don, please see my comments below: 

>About all you can conclude from the WSPR readings is the relative difference 
>between antennas. If you want to compare two horizontal antennas, place them 
>end to end. >The radiation at the end is at a minimum and the antenna will not 
>interact. 

Years ago I was under the naïve impression that if you buy a perfectly 
symmetrical GP, put it in a vertical position high up in the air, with no 
nearby metal objects, and run the coax perfectly vertically to a transmitter 
where the feeder hits the ground, you will get a nice pattern that is well 
predicted by a model. After all, the antenna manufacturer probably showed us 
that pattern in their catalog, and we have seen that pattern before in our 
antenna book. Well, not too long ago QST published an article that said 
(paraphrasing): "Not so fast. Sometimes you will get a very different pattern, 
and it may be terrible at the low elevation angles that you want." The reason: 
the feedline has current on the outside. How much will depend on its length. 
Putting a common mode choke at the feedpoint won't save you if the feedline is 
long; you may have to break up the current by several chokes along the line." 
The author supported this by theory as well as measurement. And why not? The 
feedline is a nearby metallic object, so why should it not affect the 
performance of the antenna? With that in mind, I have been expecting 
interaction also between two horizontal dipoles installed in line. I just went 
to EZNEC to check it. For the GP with a vertical, non-connected halfwave wire 
hanging under it, the center current in that wire came to about 1/4 of the GP 
drive current. The pattern was changed but not too badly. Then I modelled a 
horizontal dipole with another one mounted close off the end, in line. The 
center current in the non-driven dipole came to about 38% of the drive current 
in the driven dipole. The azimuth pattern was now a 4-clover similar to that of 
a full-wave dipole. In comparison tests where patterns are important, that is a 
lot of interaction between the two dipoles arranged end-to-end. I also modelled 
two horizontal dipoles mounted at right angles (one driven dipole end close to 
one end of non-driven dipole). Now the current in the undriven dipole got as 
high as about 58%. The azimuth pattern was now bidirectional with no difference 
front to back, but with a wider lobe on one of the sides. It seems that 
interaction is very significant regardless of orientation as long as the wires 
are close. 

>As for comparing a vertical with a horizontal antenna, or two verticals, the 
>only thing one can say is at that particular time and distance for 
>propagation, one antenna is better >than the other. That may not be true for 
>other propagation conditions, so be careful when generalizing. 
>As far as two horizonal antennas oriented in different directions, you would 
>expect greater signal strength in directions broadside to the antenna. That 
>directivity may be >useful in actual use, but is not a valid comparison 
>between the two antennas. 

Granted, but since I drank the WSPRLite antenna comparison coolaid, I view the 
ralated capability through a certain mental filter, which says, on the one 
hand, that it is a significant advancement in the art to using WSPR for antenna 
testing (the two WSPR transmitters combined with some special software 
proprietary to SOTABeams is more than just a combinati

Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Erik Basilier]

Don, please see my comments below:

>About all you can conclude from the WSPR readings is the relative difference 
>between antennas.  If you want to compare two horizontal antennas, place them 
>end to end.  >The radiation at the end is at a minimum and the antenna will 
>not interact.

Years ago I was under the naïve impression that if you buy a perfectly 
symmetrical GP, put it in a vertical position high up in the air, with no 
nearby metal objects, and run the coax perfectly vertically to a transmitter 
where the feeder hits the ground, you will get a nice pattern that is well 
predicted by a model. After all, the antenna manufacturer probably showed us 
that pattern in their catalog, and we have seen that pattern before in our 
antenna book. Well, not too long ago QST published an article that said 
(paraphrasing): "Not so fast. Sometimes you will get a very different pattern, 
and it may be terrible at the low elevation angles that you want." The reason: 
the feedline has current on the outside. How much will depend on its length. 
Putting a common mode choke at the feedpoint won't save you if the feedline is 
long; you may have to break up the current by several chokes along the line." 
The author supported this by theory as well as measurement. And why not? The 
feedline is a nearby metallic object, so why should it not affect the 
performance of the antenna? With that in mind, I have been expecting 
interaction also between two horizontal dipoles installed in line. I just went 
to EZNEC to check it. For the GP with a vertical, non-connected halfwave wire 
hanging under it, the center current in that wire came to about 1/4 of the GP 
drive current. The pattern was changed but not too badly. Then I modelled a 
horizontal dipole with another one mounted close off the end, in line. The 
center current in the non-driven dipole came to about 38% of the drive current 
in the driven dipole. The azimuth pattern was now a 4-clover similar to that of 
a full-wave dipole. In comparison tests where patterns are important, that is a 
lot of interaction between the two dipoles arranged end-to-end. I also modelled 
two horizontal dipoles mounted at right angles (one driven dipole end close to 
one end of non-driven dipole). Now the current in the undriven dipole got as 
high as about 58%. The azimuth pattern was now bidirectional with no difference 
front to back, but with a wider lobe on one of the sides. It seems that 
interaction is very significant regardless of orientation as long as the wires 
are close.

>As for comparing a vertical with a horizontal antenna, or two verticals, the 
>only thing one can say is at that particular time and distance for 
>propagation, one antenna is better >than the other.  That may not be true for 
>other propagation conditions, so be careful when generalizing.
>As far as two horizonal antennas oriented in different directions, you would 
>expect greater signal strength in directions broadside to the antenna.  That 
>directivity may be >useful in actual use, but is not a valid comparison 
>between the two antennas.

Granted, but since I drank the WSPRLite antenna comparison coolaid, I view the 
ralated capability through a certain mental filter, which says, on the one 
hand, that it is a significant advancement in the art to using WSPR for antenna 
testing (the two WSPR transmitters combined with some special software 
proprietary to SOTABeams is more than just a combination of the transmitters), 
and on the other hand that the technique is based on certain assumptions that 
need to be examined if one tries to determine the limits of what is doable and 
what is not. 

For those readers that have not looked closely at what this new approach 
involves, even if they are familiar with WSPR by iteslf, I will summarize my 
understanding here. If you run a WSPR transmitter (or two) you can go to the 
free website and get a list of stations that heard you and see the s/n ratio 
for each. You quickly get overwhelmed by all the data, The distance to the 
receiving stations that heard you is probably a positive to you, and so is the 
number of stations that heard you. Maybe you like a contest that gives you more 
points for greater distane, so you like to see dx stations in the list of 
stations that heard you. Maybe you do Field Day, and you get the same points 
regardless of distance. In either case, trying to evaluate the data presented 
to you as an antenna comparison is time-consuming and confusing. Enter 
SOTABeams. They set out to create software that takes data off the WSPR 
website, for each of the repeating WSPR transmissions, and combines it into one 
performance number for each transmission, for each of the two transmitters. The 
algorithm is proprietaty, so you don't know if a high number is high mostly 
because of good distances or because of many stations hearing you. I think we 
can assume that both distance and number of receiving stations play a role. The 
numbers we 

Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Bob McGraw K4TAX]

A relatively new ham asked for a copy or diagram of my portable antenna 
design.   Here's my response.




Welcome on being a new ham.  As to the antenna design..well 
there is no such thing in existence.


We usually camp in National parks and State parks.  There's usually a 
few to a lot of trees around.  I carry a 100 ft spool of #22 insulated 
hookup wire wound on a plastic spool.  That was the way I purchased 
it.   Once the travel trailer is in position, I will scout out a nice 
tree limb some 15 to 30 ft off of the ground.  I then unroll about 50 to 
75 ft or so of the wire from the spool, drop a half hitch around the 
spool to prevent the remainder of the wire from rolling off of the 
spool.  Using a method similar to that of "David when he slew the 
Giant", I hurl the spool over a limb.  Of course sometimes my estimated 
distance or height is in error and I find it necessary to make another 
attempt or two.  The spool and wire simply keep the wire taught over the 
limb and to the trailer.  On the trailer, I have a feed through which 
was originally for a TV antenna, no longer used for that purpose.  To 
this I attach the end of the wire to the F connector.  Inside I have a 
length of RG 58 coax that runs to the F connector and terminates into a 
BNC connectro.  This attaches to my home made L network for the tuner.  
The L network is comprised of a single variable C of about 500 pF and an 
air wound inductor which is  1 1/2" in diameter and about 6" long.  I 
have a 20 position tap switch that is configured so I can use individual 
tap or select turns of the inductor.  This is mounted in a4" x 4" x 8" 
aluminum  box with a BNC on each end.    I recall having about every 2 
turns tapped to the switch.  Using this L network I can find a point of 
C and L values which produce suitable SWR, less than 2:1 for my 
operation.   After all my RG-58 is only 6 ft long so there is little 
loss on HF in the "feed line".   If this doesn't find a match, I just 
reverse the IN and OUT to provide a different impedance range.     
Should I then have difficulty in obtaining a match, I will loosen the 
wire, allow more to spool off and then try again.   Usually a length of 
some 50 to 75 feet will work about any band except 160 M.   I need more 
wire for that. When we are finished camping, I turn the end of the wire 
loose at the trailer allowing the spool and wire to fall to the ground, 
wind it up and stow it for the next adventure.    All of this is best 
described as an end fed long wire with a L matching network.    There is 
nothing exotic about it, no baluns, no specific lengths, just use the 
wire length and space available.


In reading the various posts and opinions on the topic, I'm amazed at 
the lengths, expense and trouble many hams go to in order to put up an 
antenna.


Hope this helps

***

73

Bob, K4TAX


On 11/21/2017 6:06 PM, Ignacy wrote:

Antenna performance does not depend on how it is fed (if feeder losses are
low) but on height and ground type. For KX3 with AT, any special length
makes little sense, especially in portable conditions. KX3 matches most
random wires, and KX3 with 4:1 balun matches any wires. Lack of balance is
not too important with battery operation. I try to make random wire +
counterpoise at least 1/4 wave on the lowest frequency for reasonable
efficiency.

For 1.5 KW, an endfed with a 49:1 or so transformer makes lots of sense as
wideband tuners for QRO are rare, expensive and heavy. "Myantennas.com"
perfected a  transformer that has very small losses and does not
self-destroy at high power. But in inv V configuration, it is way down from
a flattop.

Ignacy, NO9E



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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Ignacy Misztal]

I tested the endfed from myantennas at 1 kw. The transformer was only warm
so no significant losses there. The feeder was RF hot so a toroid choke was
added. Cable no longer hot and toroid cold. SWR low on many bands. So the
only significant losses could have been through the ground.

This is obvious after a bit of thought. A vertical or inv L ( or low inv V)
needs either good ground or lots of radials for small ground losses. With
endfed, there is one radial, the feeder. So excellent performance by the
beach, not bad in good ground, so so in poor ground.

Ignacy

On Nov 21, 2017 7:58 PM, "Erik Basilier" <ebasil...@cox.net> wrote:

Ignacy,
For an end-fed wire, I would see the possibility of power losses not only in
the feed feeder, but also in the tuner, the transformer, and the effective
counterpoise path. For low counterpoise losses, small counterpoise current
is desirable, which means a high antenna impedance. When a long counterpoise
wire is needed, and when that wire is close to the ground, I would also
expect ground losses from the counterpoise current interacting with the
ground, in addition to the ground losses caused by the antenna wire
interacting with the ground. When the feeder (outside or shield)-tuner-radio
path carries all or part of the counterpoise current, I would not rule out
the possibility that the possibiility that the resistance there is
sufficient to cause losses significant enough to affect overall efficiency
of the system. That is why I would like to compare like antennas with
different feed systems. Of course antenna wire configuration is the most
important thing to determine overall performance, but when putting up a long
wire, I usually start with the support structure that already exists, or
that I can put up most easily.

73,
Erik K7TV

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ignacy
Sent: Tuesday, November 21, 2017 5:07 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30

Antenna performance does not depend on how it is fed (if feeder losses are
low) but on height and ground type. For KX3 with AT, any special length
makes little sense, especially in portable conditions. KX3 matches most
random wires, and KX3 with 4:1 balun matches any wires. Lack of balance is
not too important with battery operation. I try to make random wire +
counterpoise at least 1/4 wave on the lowest frequency for reasonable
efficiency.

For 1.5 KW, an endfed with a 49:1 or so transformer makes lots of sense as
wideband tuners for QRO are rare, expensive and heavy. "Myantennas.com"
perfected a  transformer that has very small losses and does not
self-destroy at high power. But in inv V configuration, it is way down from
a flattop.

Ignacy, NO9E



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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Don Wilhelm]

Erik,

About all you can conclude from the WSPR readings is the relative 
difference between antennas.  If you want to compare two horizontal 
antennas, place them end to end.  The radiation at the end is at a 
minimum and the antenna will not interact.


As for comparing a vertical with a horizontal antenna, or two verticals, 
the only thing one can say is at that particular time and distance for 
propagation, one antenna is better than the other.  That may not be true 
for other propagation conditions, so be careful when generalizing.


As far as two horizonal antennas oriented in different directions, you 
would expect greater signal strength in directions broadside to the 
antenna.  That directivity may be useful in actual use, but is not a 
valid comparison between the two antennas.


73,
Don W3FPR

On 11/21/2017 8:40 PM, Erik Basilier wrote:

I hope my interest in WSPRLite antenna comparisons doesn't lead this thread too 
far off topic, but I have further thoughts on how to orient the two antennas 
being compared.

Frank, who is much more experienced with this comparison system, suggested that 
two horizontally polarized antennas should be oriented end-to end, due to 
parasitic interacton between the antennas. I questioned whether the end-to-end 
configuration would be free from interactions. Be that as it may, but while 
thinking about configuration choices, I came up with another reason why 
end-to-end would be the right thing to do.

Suppose we are comparing two omnidirectional antennas such as verticals. Even 
if the receiving stations are unevenly distributed in different directions, the 
comparison based on received reports should be fair. If instead we are 
comparing two horizontal dipoles, that are not pointing in the same direction, 
and receiving stations are not distributed evenly in all directions, the 
antenna with fewer receivers in the main lobes would likely be at a 
disadvantage. If the feed system is the part that is different between the two 
ontennas, one could compensate, as I suggested, by swapping antennas for each 
feed system, but the time taken allows the conditions to change, so one would 
probably have to go back and forth a number of times to gain confidence in any 
observed difference in performance. Close to the coast receiving stations would 
be largely missing in roughtly half of possible compass directions, and 
unidirectional antennas would be affected more than a dipole with its bid

irectional pattern. Much seems to depend on the proprietary algorithm used to 
composite a single performance number for from the WSPR received s/n rations at 
multiple receiving stations. What is the balance between the number of good 
reception reports vs. the distance for each one? When we talk about difficulty 
in comparing one vertical and one horizontal antenna, I suspect that similar 
considerations may account for result being inconsistent or difficult to 
interpret.



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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Erik Basilier]

I hope my interest in WSPRLite antenna comparisons doesn't lead this thread too 
far off topic, but I have further thoughts on how to orient the two antennas 
being compared.

Frank, who is much more experienced with this comparison system, suggested that 
two horizontally polarized antennas should be oriented end-to end, due to 
parasitic interacton between the antennas. I questioned whether the end-to-end 
configuration would be free from interactions. Be that as it may, but while 
thinking about configuration choices, I came up with another reason why 
end-to-end would be the right thing to do.

Suppose we are comparing two omnidirectional antennas such as verticals. Even 
if the receiving stations are unevenly distributed in different directions, the 
comparison based on received reports should be fair. If instead we are 
comparing two horizontal dipoles, that are not pointing in the same direction, 
and receiving stations are not distributed evenly in all directions, the 
antenna with fewer receivers in the main lobes would likely be at a 
disadvantage. If the feed system is the part that is different between the two 
ontennas, one could compensate, as I suggested, by swapping antennas for each 
feed system, but the time taken allows the conditions to change, so one would 
probably have to go back and forth a number of times to gain confidence in any 
observed difference in performance. Close to the coast receiving stations would 
be largely missing in roughtly half of possible compass directions, and 
unidirectional antennas would be affected more than a dipole with its 
bidirectional pattern. Much seems to depend on the proprietary algorithm used 
to composite a single performance number for from the WSPR received s/n rations 
at multiple receiving stations. What is the balance between the number of good 
reception reports vs. the distance for each one? When we talk about difficulty 
in comparing one vertical and one horizontal antenna, I suspect that similar 
considerations may account for result being inconsistent or difficult to 
interpret.

73,
Erik K7TV

-Original Message-
From: elecraft-boun...@mailman.qth.net 
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Erik Basilier
Sent: Sunday, November 19, 2017 11:13 PM
To: donov...@starpower.net; elecraft@mailman.qth.net
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30

Hi Frank,

 

Thanks for your very useful comments. Below my answers:

 

>Radiation results from RF current flowing in an antenna.  An RF

>ammeter is a useful instrument for measuring the relative efficiency

>different types of matching networks feeding similar antennas.

Granted. I might want to add that to my plans. I know that the WSPRLite 
tolerates no more than 100 mW of reflected power, and to avoid accident risk I 
intend to set the transmit power to no more than 100 mW. I do not know how the 
units might fold back transmit power in a scenario where the SWR is good but 
less than perfect. For this reason I am planning to use a tuner whenever SWR is 
not very close to ideal. The location of the tuner would be wherever it would 
make sense to place it in field operation. If I add ammeters, they would be 
placed at the feedpoint, which should work well when I compare different 
impedance transformers using identical wires. If I compare to non-resonant 
wires or center feed, it would be hard to compare ammeter readings.

 

> 1.  The two antennas under test should be located within less than

>one wavelength of each other, otherwise independent selective fading

>becomes a significant source of measurement error.  

Interesting. You are saying that this applies even if the comparison is done 
over several hours?

In my limited back yard, and because I want the feedpoints close to each other, 
I will certainly meet the requirement of staying withing one wavelength.

 

>2;  Horizontally polarized antennas should be oriented end-to-end

>to each other to avoid significant parasitic interaction that washes

>out the other differences in antenna performance

My earlier comments about end-fed antennas focused on vertical wires since the 
thread originator had tall trees that suggest vertical orientation. My 
preferred 24” support poles used with 60+ ft wires lead me to the inverted vee 
configuration which will be horizontally polarized. I am surprised that you can 
avoid parasitic interaction if you place the wires end-to-end. I was under the 
impression that end-to-end vertical wires, as in an elevated vertical with a 
resonant length of vertical feedline under it, with a common mode choke 
preventing current going from the radiator to the coax shield, would still 
suffer from parasitic coupling unless an additional common mode choke is added 
somewhere along the feedline to break up the resonance. I am influenced here by 
a QST article about vhf/uhf verticals where it seemed that multiple common mode 
chokes were found necessary to

Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Erik Basilier]

Ignacy, 
For an end-fed wire, I would see the possibility of power losses not only in
the feed feeder, but also in the tuner, the transformer, and the effective
counterpoise path. For low counterpoise losses, small counterpoise current
is desirable, which means a high antenna impedance. When a long counterpoise
wire is needed, and when that wire is close to the ground, I would also
expect ground losses from the counterpoise current interacting with the
ground, in addition to the ground losses caused by the antenna wire
interacting with the ground. When the feeder (outside or shield)-tuner-radio
path carries all or part of the counterpoise current, I would not rule out
the possibility that the possibiility that the resistance there is
sufficient to cause losses significant enough to affect overall efficiency
of the system. That is why I would like to compare like antennas with
different feed systems. Of course antenna wire configuration is the most
important thing to determine overall performance, but when putting up a long
wire, I usually start with the support structure that already exists, or
that I can put up most easily.

73,
Erik K7TV

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Ignacy
Sent: Tuesday, November 21, 2017 5:07 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30

Antenna performance does not depend on how it is fed (if feeder losses are
low) but on height and ground type. For KX3 with AT, any special length
makes little sense, especially in portable conditions. KX3 matches most
random wires, and KX3 with 4:1 balun matches any wires. Lack of balance is
not too important with battery operation. I try to make random wire +
counterpoise at least 1/4 wave on the lowest frequency for reasonable
efficiency. 

For 1.5 KW, an endfed with a 49:1 or so transformer makes lots of sense as
wideband tuners for QRO are rare, expensive and heavy. "Myantennas.com"
perfected a  transformer that has very small losses and does not
self-destroy at high power. But in inv V configuration, it is way down from
a flattop.

Ignacy, NO9E  



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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Ignacy]

Antenna performance does not depend on how it is fed (if feeder losses are
low) but on height and ground type. For KX3 with AT, any special length
makes little sense, especially in portable conditions. KX3 matches most
random wires, and KX3 with 4:1 balun matches any wires. Lack of balance is
not too important with battery operation. I try to make random wire +
counterpoise at least 1/4 wave on the lowest frequency for reasonable
efficiency. 

For 1.5 KW, an endfed with a 49:1 or so transformer makes lots of sense as
wideband tuners for QRO are rare, expensive and heavy. "Myantennas.com"
perfected a  transformer that has very small losses and does not
self-destroy at high power. But in inv V configuration, it is way down from
a flattop.

Ignacy, NO9E  



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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Bob McGraw K4TAX]

For that very reason, in our camper operation, I use a end fed antenna.  
The matching network is a tapped coil and variable C forming an L 
network.  The circuit is in a small plastic box with a SO-239 on each 
end, thus it is reversible.   This allows a wide range of impedance 
selections, plus the L network, unlike a T network, will only resolve a 
match at one value combination of L and C values.


I carry a 100 ft spool of #22 insulated hook up wire.  Unroll some 
estimated length, drop a half hitch around the spool and toss the spool 
over a convenient limb.   When ready to retrieve the antenna, turn the 
feed end loose and let the spool drop to the ground.  I've never 
experienced a length or condition where I could not satisfactorily match 
the band/frequency I wanted to use.


73

Bob, K4TAX


On 11/19/2017 10:26 PM, K9MA wrote:

On 11/19/2017 02:22, Erik Basilier wrote:

The second approach, used by MyAntennas and others seems to use a
transformer with much higher impedance ratio. One way to construct 
such a

transformer would be to cascade two 9:1 units for an effective ratio of
81:1.


While I haven't tried it, it would probably be very hard to build a 
pair of 9:1 transformers or a single 81:1 transformer with low enough 
stray capacitance to work on the higher bands.  It might work up to 40 
meters, I suppose.


The big advantage of a resonant end-fed half wave is that very little 
current flows in the ground system or counterpoise, so most of the 
power is going into the antenna.  While it is hard to match that high 
impedance with a non-resonant transformer, it is very easy to match 
with a simple L network.  The only reason the internal ATU in the KX3, 
etc., can't match it is that it doesn't have enough range.  (And for 
good reason.)  An external L network consisting of a tapped coil and 
variable capacitor will do it nicely.


73,

Scott K9MA




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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Erik Basilier]

Hi Frank,

 

Thanks for your very useful comments. Below my answers:

 

>Radiation results from RF current flowing in an antenna.  An RF

>ammeter is a useful instrument for measuring the relative efficiency

>different types of matching networks feeding similar antennas.

Granted. I might want to add that to my plans. I know that the WSPRLite 
tolerates no more than 100 mW of reflected power, and to avoid accident risk I 
intend to set the transmit power to no more than 100 mW. I do not know how the 
units might fold back transmit power in a scenario where the SWR is good but 
less than perfect. For this reason I am planning to use a tuner whenever SWR is 
not very close to ideal. The location of the tuner would be wherever it would 
make sense to place it in field operation. If I add ammeters, they would be 
placed at the feedpoint, which should work well when I compare different 
impedance transformers using identical wires. If I compare to non-resonant 
wires or center feed, it would be hard to compare ammeter readings.

 

> 1.  The two antennas under test should be located within less than

>one wavelength of each other, otherwise independent selective fading

>becomes a significant source of measurement error.  

Interesting. You are saying that this applies even if the comparison is done 
over several hours?

In my limited back yard, and because I want the feedpoints close to each other, 
I will certainly meet the requirement of staying withing one wavelength.

 

>2;  Horizontally polarized antennas should be oriented end-to-end

>to each other to avoid significant parasitic interaction that washes

>out the other differences in antenna performance

My earlier comments about end-fed antennas focused on vertical wires since the 
thread originator had tall trees that suggest vertical orientation. My 
preferred 24” support poles used with 60+ ft wires lead me to the inverted vee 
configuration which will be horizontally polarized. I am surprised that you can 
avoid parasitic interaction if you place the wires end-to-end. I was under the 
impression that end-to-end vertical wires, as in an elevated vertical with a 
resonant length of vertical feedline under it, with a common mode choke 
preventing current going from the radiator to the coax shield, would still 
suffer from parasitic coupling unless an additional common mode choke is added 
somewhere along the feedline to break up the resonance. I am influenced here by 
a QST article about vhf/uhf verticals where it seemed that multiple common mode 
chokes were found necessary to prevent feedline radiation. Anyway, these 
situations should be easy to model, and I assume you have looked closely at it. 
I should have enough room to place my inverted vee’s end-to-end if you are sure 
that is the best way. 

 

>3,  Do not attempt to compare horizontally polarized antennas to

>vertically polarized antennas, independent selective fading

>becomes a significant source of measurement error that takes

>an extraordinary amount of data collection to overcome.

Comparison between horizontal and vertical configuration is not part of my 
present plans, but I have to admit previously comparing my R5 vertical to my 
horizontal HF beam. I ran it several hours in several sessions at different 
times.There were times of day where sometimes the vertical seemed to work 
better than the beam, although overall the beam looked much better. Do I 
understand you to say that this comparison was flawed because of insufficient 
time spent?

 

73,

Erik K7TV

 

>Enjoy!

 

>73

>Frank

>W3LPL

 

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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Brian Hunt]

For several years I've been using a 33 ft wire and a pair of small 
tapped loading coils to get  an EFHW vertical resonant on 20m. 30m and 
40m.  It's fed with a link coupled tuned tank circuit consisting of a 
coil on a 1 inch powdered iron toroid and an air variable capacitor.  
The link consists of 1-6 switch selected turns which gives a wide range 
of impedance transformation.  Antenna is supported with a 33 ft MFJ 
fiberglass mast.  Easy to set up and tune.  I do have to haul the wire 
down to change the taps and retune for a band change.  Used with a K1 or 
KX2, the internal ATU is usually in bypass.


73,
Brian, K0DTJ
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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[K9MA]

On 11/19/2017 02:22, Erik Basilier wrote:

The second approach, used by MyAntennas and others seems to use a
transformer with much higher impedance ratio. One way to construct such a
transformer would be to cascade two 9:1 units for an effective ratio of
81:1.


While I haven't tried it, it would probably be very hard to build a pair 
of 9:1 transformers or a single 81:1 transformer with low enough stray 
capacitance to work on the higher bands.  It might work up to 40 meters, 
I suppose.


The big advantage of a resonant end-fed half wave is that very little 
current flows in the ground system or counterpoise, so most of the power 
is going into the antenna.  While it is hard to match that high 
impedance with a non-resonant transformer, it is very easy to match with 
a simple L network.  The only reason the internal ATU in the KX3, etc., 
can't match it is that it doesn't have enough range.  (And for good 
reason.)  An external L network consisting of a tapped coil and variable 
capacitor will do it nicely.


73,

Scott K9MA

--
Scott  K9MA

k...@sdellington.us

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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[donovanf]

Hi Erik, 


Radiation results from RF current flowing in an antenna. An RF 
ammeter is a useful instrument for measuring the relative efficiency 
different types of matching networks feeding similar antennas. 


I'm well familiar with the simultaneous synchronized WSPRlite 
antenna performance analysis techniques, I developed the techniques 
that SOTAbeams implemented earlier this year! They work very, 
very well but a few things must be done to avoid significant 
measurement errors and biases: 


1. The two antennas under test should be located within less than 
one wavelength of each other, otherwise independent selective fading 
becomes a significant source of measurement error. 


2; Horizontally polarized antennas should be oriented end-to-end 
to each other to avoid significant parasitic interaction that washes 
out the other differences in antenna performance 


3, Do not attempt to compare horizontally polarized antennas to 
vertically polarized antennas, independent selective fading 
becomes a significant source of measurement error that takes 
an extraordinary amount of data collection to overcome. 


Enjoy! 


73 
Frank 
W3LPL 






- Original Message -

From: "Erik Basilier" <ebasil...@cox.net> 
To: donov...@starpower.net, elecraft@mailman.qth.net 
Sent: Monday, November 20, 2017 1:51:47 AM 
Subject: RE: [Elecraft] KX3 Field Ant. for 80/40/30 



I am well aware of that, Frank, and in fact I have multiple cores sitting here 
waiting for such measurements. However, performance of an isolated component is 
less important than overall system performance, where the matching to antenna 
impedance as well as counterpoise current routing and losses all play in. After 
the component testing to qualify different transformers as having low loss, I 
am planning to test different versions of resonant and non-resonant end-fed 
antennas against each other in pairs. The resonant (very high impedance) 
versons will include different transformer ratios. I may even include versions 
where the impedance transformation is performed with a tapped, tuned 
parallel-resonant circuit, which is the classic approach from the Zeppelin 
days. I may also include a center-fed dipole (conventional, K9YC?, sleeve 
around coax?). To be able to compare antenna systems with potentially small 
differences, I am set up with a pair of WSPRLite transmitters that let me run 
both antennas simultaneously in synchronization. In this type of testing one 
obtains two overlaid graphs representing the two antennas under test, versus 
time. Each value shows a composite number based on s/n ratios at a number of 
different receiving stations. Over time, the two curves tend to cross back and 
forth against each other, but over a few hours one can see whether one tends to 
dominate over the other. Transmission frequencies will not be exactly the same, 
but the difference will be very small. When done in my back yard, both antennas 
in a test will be influenced by all kinds of metal structures around it, 
including my tower, power lines, metal in the house, and the other antenna 
under test. I will minimize the latter by erecting the wires at 90 degrees 
angle, with the feed points close together, so that I can always reach both 
transmitters at the same time to push the start buttons at the same time. My 
main method of compensating for interactions with metal objects will be to swap 
the matching/feeding systems while keeping the radiators and transmitters in 
place. I like to deploy wire antennas in the field on 24 ft masts, so I will 
use two of those for the testing and arrange the two wires as inverted vee’s. 
For reasons of space, I will not include 80 m, so the two wires will be in the 
60+ foot range, except for the non-resonant version where 50+ feet are commonly 
used. For possible tests using center feed, I would use different arrangements 
that all resonate as ½ wavelength on 40. By comparing two antenna systems at a 
time, each time taking the winner to compare with the next antenna, I hope to 
determine an idea of what works best for me in field use. 

73, 
Erik K7TV 



From: donov...@starpower.net [mailto:donov...@starpower.net] 
Sent: Sunday, November 19, 2017 3:33 PM 
To: elecraft@mailman.qth.net 
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30 


Its easy to measure transformer loss by measuring the loss through 

a pair of identical transformers connected to back-to-back. 



The loss in a single transformer will be half of the loss through the 

back-to-back pair. 



73 

Frank 

W3LPL 


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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Erik Basilier]

I am well aware of that, Frank, and in fact I have multiple cores sitting here 
waiting for such measurements. However, performance of an isolated component is 
less important than overall system performance, where the matching to antenna 
impedance as well as counterpoise current routing and losses all play in. After 
the component testing to qualify different transformers as having low loss, I 
am planning to test different versions of resonant and non-resonant end-fed 
antennas against each other in pairs. The resonant (very high impedance) 
versons will include different transformer ratios. I may even include versions 
where the impedance transformation is performed with a tapped, tuned 
parallel-resonant circuit, which is the classic approach from the Zeppelin 
days. I may also include a center-fed dipole (conventional, K9YC?, sleeve 
around coax?). To be able to compare antenna systems with potentially small 
differences, I am set up with a pair of WSPRLite transmitters that let me run 
both antennas simultaneously in synchronization. In this type of testing one 
obtains two overlaid graphs representing the two antennas under test, versus 
time. Each value shows a composite number based on s/n ratios at a number of 
different receiving stations. Over time, the two curves tend to cross back and 
forth against each other, but over a few hours one can see whether one tends to 
dominate over the other. Transmission frequencies will not be exactly the same, 
but the difference will be very small. When done in my back yard, both antennas 
in a test will be influenced by all kinds of metal structures around it, 
including my tower, power lines, metal in the house, and the other antenna 
under test. I will minimize the latter  by erecting the wires at 90 degrees 
angle, with the feed points close together, so that I can always reach both 
transmitters at the same time to push the start buttons at the same time. My 
main method of compensating for interactions with metal objects will be to swap 
the matching/feeding systems while keeping the radiators and transmitters in 
place. I like to deploy wire antennas in the field on 24 ft masts, so I will 
use two of those for the testing and arrange the two wires as inverted vee’s. 
For reasons of space, I will not include 80 m, so the two wires will be in the 
60+ foot range, except for the non-resonant version where 50+ feet are commonly 
used. For possible tests using center feed, I would use different arrangements 
that all resonate as ½ wavelength on 40. By comparing two antenna systems at a 
time, each time taking the winner to compare with the next antenna, I hope to 
determine an idea of what works best for me in field use.

 

73,

Erik K7TV

 

From: donov...@starpower.net [mailto:donov...@starpower.net] 
Sent: Sunday, November 19, 2017 3:33 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30

 

Its easy to measure transformer loss by measuring the loss through

a pair of identical transformers connected to back-to-back.  

 

The loss in a single transformer will be half of the loss through the

back-to-back pair.

 

73

Frank

W3LPL

 

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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[donovanf]

Its easy to measure transformer loss by measuring the loss through 
a pair of identical transformers connected to back-to-back. 


The loss in a single transformer will be half of the loss through the 
back-to-back pair. 


73 
Frank 
W3LPL 

- Original Message -

From: "Erik Basilier" <ebasil...@cox.net> 
To: "Bill Frantz" <fra...@pwpconsult.com> 
Cc: elecraft@mailman.qth.net 
Sent: Sunday, November 19, 2017 10:14:41 PM 
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30 

Bill, I am aware of Jim's innovative way of achieving center feed while 
seemingly attaching the feeder to the end. It should be useful in some 
situations. However, the thread creator wanted coverage of 4 bands with one 
antenna, and my personal interest right now is also solutions that cover 
serveral bands without adjustments and compromises. With that as the goal, I 
see no theoretical reason to want center feed. Only by feeding at the end can 
you get approximately the same impedance for each band, without moving the 
feedpoint, for so many bands. (That said, if you compare reality side-by-side 
to a map, reality tends to win. It would be interesting to compare side-by-side 
to make sure that the high-ratio transformer isn't lossy enough to hurt 
performance.) If you are looking at a single band, with a 1/2 wave vertical 
wire. The current distribution should theoretically be the same whether we feed 
it at the bottom or if we move the feed point to the center at the cost of 1/4 
wav
  
elength of additional coax plus the cost of the common mode choke (but there 
may be another justification to have the choke anyway). If one is willing to 
compromise the requirement of covering several bands with very good match, 
there is also the option of Off-Center-Feed, which can allow operation on 
several bands, but the match on most or all bands will be a compromise that 
likely forces the use of a tuner, similar to the situation with an end-fed with 
9:1 impedance transformer. If you compare the OCF with the end-fed with 9:1 
impedance transformer, it is not clear to me which one has the edge in 
practical use (assuming both have the antenna wire suspended and shaped 
similarly). For the OCF the results will depend on the selection of feedpoint, 
and for the end-fed there is room for a wide range of wire lengths that are 
non-resonant and should produce "medium impedance". One can easily find 
suggestions online for both designs. However, it seems to me that the 9:1 fans 
are 
more prone to use low elevations and shapes that reduce performance. 

73, 
Erik K7TV 

-Original Message- 
From: Bill Frantz [mailto:fra...@pwpconsult.com] 
Sent: Sunday, November 19, 2017 1:03 PM 
To: Erik Basilier <ebasil...@cox.net> 
Cc: 'JT Croteau' <jt.to...@gmail.com>; elecraft@mailman.qth.net 
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30 

A useful post Erik. 

Also useful is the "pseudo end-fed" design that K9YC shows on 
<http://k9yc.com/VerticalHeight.pdf> starting at page 70. This design is really 
a center fed dipole using the outside of the feed line coax as one half of the 
dipole and an extension of the center conductor as the other. The RF-electrical 
length of the feed line outside is controlled by a common-mode choke on the 
feed line. 

I built one of these for 30 meters and found that the best tuning occured when 
the coax shield between the common-mode choke and the "center" feed location 
was slightly shorter than the other half of the dipole. 

73 Bill AE6JV 


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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Erik Basilier]

Bill, I am aware of Jim's innovative way of achieving center feed while 
seemingly attaching the feeder to the end. It should be useful in some 
situations. However, the thread creator wanted coverage of 4 bands with one 
antenna, and my personal interest right now is also solutions that cover 
serveral bands without adjustments and compromises. With that as the goal, I 
see no theoretical reason to want center feed. Only by feeding at the end can 
you get approximately the same impedance for each band, without moving the 
feedpoint, for so many bands. (That said, if you compare reality side-by-side 
to a map, reality tends to win. It would be interesting to compare side-by-side 
to make sure that the high-ratio transformer isn't lossy enough to hurt 
performance.) If you are looking at a single band, with a 1/2 wave vertical 
wire. The current distribution should theoretically be the same whether we feed 
it at the bottom or if we move the feed point to the center at the cost of 1/4 
wav
 elength of additional coax plus the cost of the common mode choke (but there 
may be another justification to have the choke anyway).  If one is willing to 
compromise the requirement of covering several bands with very good match, 
there is also the option of Off-Center-Feed, which can allow operation on 
several bands, but the match on most or all bands will be a compromise that 
likely forces the use of a tuner, similar to the situation with an end-fed with 
9:1 impedance transformer. If you compare the OCF with the end-fed with 9:1 
impedance transformer, it is not clear to me which one has the edge in 
practical use (assuming both have the antenna wire suspended and shaped 
similarly). For the OCF the results will depend on the selection of feedpoint, 
and for the end-fed there is room for a wide range of wire lengths that are 
non-resonant and should produce "medium impedance". One can easily find 
suggestions online for both designs. However, it seems to me that the 9:1 fans 
are 
 more prone to use low elevations and shapes that reduce performance. 

73,
Erik K7TV

-Original Message-
From: Bill Frantz [mailto:fra...@pwpconsult.com] 
Sent: Sunday, November 19, 2017 1:03 PM
To: Erik Basilier <ebasil...@cox.net>
Cc: 'JT Croteau' <jt.to...@gmail.com>; elecraft@mailman.qth.net
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30

A useful post Erik.

Also useful is the "pseudo end-fed" design that K9YC shows on 
<http://k9yc.com/VerticalHeight.pdf> starting at page 70. This design is really 
a center fed dipole using the outside of the feed line coax as one half of the 
dipole and an extension of the center conductor as the other. The RF-electrical 
length of the feed line outside is controlled by a common-mode choke on the 
feed line.

I built one of these for 30 meters and found that the best tuning occured when 
the coax shield between the common-mode choke and the "center" feed location 
was slightly shorter than the other half of the dipole.

73 Bill AE6JV


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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Erik Basilier]

That group sounds interesting, thanks.
73,
Erik K7TV

-Original Message-
From: VE3GAM [mailto:ve3...@rogers.com] 
Sent: Sunday, November 19, 2017 12:09 PM
To: Erik Basilier <ebasil...@cox.net>; 'JT Croteau' <jt.to...@gmail.com>;
elecraft@mailman.qth.net
Cc: Al VE3GAM <ve3...@rogers.com>
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30

there is an End Fed Half Wave Antenna group on Facebook started up by N4LQ.
it certainly promotes the EFHW fed with a 49:1 transformer. Steve loves the
EFHW, but really does not have much love for 9:1 unun antenna. still, it is
an interesting group to monitor.

al ve3gam


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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Bill Frantz]

A useful post Erik.

Also useful is the "pseudo end-fed" design that K9YC shows on 
 starting at page 70. This 
design is really a center fed dipole using the outside of the 
feed line coax as one half of the dipole and an extension of the 
center conductor as the other. The RF-electrical length of the 
feed line outside is controlled by a common-mode choke on the 
feed line.


I built one of these for 30 meters and found that the best 
tuning occured when the coax shield between the common-mode 
choke and the "center" feed location was slightly shorter than 
the other half of the dipole.


73 Bill AE6JV

On 11/19/17 at 12:22 AM, ebasil...@cox.net (Erik Basilier) wrote:


End-fed antennas have gotten popular lately. When I look closer I see two
different popular approaches.


---
Bill Frantz| "I wish there was a knob on the TV to turn 
up the
408-356-8506   | intelligence.  There's a knob called 
"brightness", but

www.pwpconsult.com | it doesn't work. -- Gallagher

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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[VE3GAM]

there is an End Fed Half Wave Antenna group on Facebook
started up by N4LQ. it certainly promotes the EFHW fed with
a 49:1 transformer. Steve loves the EFHW, but really does not
have much love for 9:1 unun antenna. still, it is an interesting
group to monitor.

al ve3gam

--
From: "Erik Basilier" <ebasil...@cox.net>
Sent: Sunday, November 19, 2017 3:22 AM
To: "'JT Croteau'" <jt.to...@gmail.com>; <elecraft@mailman.qth.net>
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30


End-fed antennas have gotten popular lately. When I look closer I see two
different popular approaches.

The first uses a 9:1 impedance transformer in combination with a wire 
length

that is not resonant on any band. The idea is that (assuming there is no
significant feedline length) you have a medium impedance (450 ohms) on the
antenna side of the transformer, and because the wire is not resonant so 
you

might have an impedance into the wire that is also "medium". By adjusting
the wire length, you might get pretty close to 450 ohms on one or two 
bands,
and with a wide range tuner you can probably get below swr 2:1 for the 
radio

PA to see.

The second approach, used by MyAntennas and others seems to use a
transformer with much higher impedance ratio. One way to construct such a
transformer would be to cascade two 9:1 units for an effective ratio of
81:1. This would mean the wire should present an impedance of 4000 ohms or
so. Another way would be using a single tranformer with a higher ratio. 
The
impedance ratio is the square of the turns ratio. With a turns ratio of 
9:1

you should again get to about 4000 ohms. Somewhere I saw somebody using an
8:1 turns ratio for an ideal antenna wire impedance of about 3200 ohms.
These impedance levels are achieved by using a resonant wire.

I don't know how you arrived at your parameters, but your wire length is 
too
close to resonance on 80 and 40. Your transformer ratio wants a 
non-resonant
wire, so you might see better results if you shorten the wire 
significantly
and keep using the KX3 ATU. Alternatively, you could replace the 
transformer

for a much higher impedance ratio, in which case you can probably operate
with the tuner bypassed at least on 80 and 40 with a well adjusted wire
length. With this approach you want the wire resonant on each band. It
should be easy to achieve resonance on 80, 40, 20 and 10. As you double 
the

frequency, you are changing the number of half wavelengths covered by the
wire; the end feedpoint is always at the end of one of these half
wavelengths, and thus you get the very high impedance that you seek. 30
meters does not fit as clearly into this scheme. The commercial versions 
use

a small coil in the wire located close to the transformer end, and seem to
be able to achieve a reasoable match for all the bands 80 and up without
using a tuner. Now if you had placed the feedpoint in the center you would
not have been able to get this consistency of feedpoint impedance from 
band

to band. As I see it, this is a major reason for the popularity of the
end-fed approach as contrasted to the conventional center-fed approach. 
Note
that the 30m coverage of the 80 meter and up design is not replicated if 
you
try the same approach with half the wire length. In this case you will 
need

a tuner to get reasonable swr on 30.

An important consideration is antenna height. We all know that antennas
usually work better when placed higher. Looking a bit closer, we can look
beyond the general installation height and consider the height(s) of the
antenna part(s) that carry the most current. Antenna modelling may 
calculate
the field as resulting from current levels in different individual pieces 
of
the wire, and then it makes sense to elevate those portions more than 
other

parts of the wire that carry less current. Another reason for this is the
effect of ground losses. Jim Brown, in his article that he just linked to,
shows that ground losses get worse the closer a vertical antenna is to
ground. This makes sense as currents in the lossy soil are caused by
induction from currents in the antenna. When we look at the current
distribution within the vertical antenna wire it again makes sense to 
place

the part(s) of the wire with high current higher rather than lower. One of
the simplest portable antennas is a short wire or whip of a quarter wave 
or

less. It will have a low feedpoint impedance that can probably be matched
reasonably without a tuner or with a limited-range tuner. However, with a
low impedance comes a current maximum at the feedpoint. This often means
close to the ground, so even with a good set of elevated radials,
considerable ground losses could be expected. (An actual connection to the
soil would generally be much worse, unless you bury a lot of wires.) With 
a

longer wire (1/2 wavelengh at the lowest band) we can have a very high
feedpoint impedanc

Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Lynn W. Taylor, WB6UUT]

If the wire is near an even multiple of 1/4 wave (1/2 wave, one full 
wave, 1 1/2 wave, etc.) then the impedance at the end of the wire is 
going to be very high.


If the wire is near an odd multiple of 1/4 wave (1/4 wave, 3/4 wave, 1 
1/4 wave) then the impedance will be low.


If you're expecting a high impedance and you have a 3/4 wave wire, you 
may have trouble getting a match with a 9:1 balun.


That's oversimplified, of course.

The reason "pseudo-random" antennas around 53' are popular is that 
length isn't resonant on any popular ham band, and you can start making 
assumptions about how it'll work.


73 -- Lynn

On 11/19/2017 12:22 AM, Erik Basilier wrote:

End-fed antennas have gotten popular lately. When I look closer I see two
different popular approaches.

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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[JT Croteau]

with a limited-range tuner. However, with a
>> low impedance comes a current maximum at the feedpoint. This often means
>> close to the ground, so even with a good set of elevated radials,
>> considerable ground losses could be expected. (An actual connection to the
>> soil would generally be much worse, unless you bury a lot of wires.) With
>> a
>> longer wire (1/2 wavelengh at the lowest band) we can have a very high
>> feedpoint impedance, very low feedpoint current, and more elevated
>> location(s) of high curent portion(s) of the antenna, for lower ground
>> losses.
>>
>> Any antenna feed point needs to provide two terminals for the feed current
>> to flow through a complete circuit. A end-fed designed for medium to high
>> feed impedance has small feed current. In practice this means that
>> whatever
>> is used as the counterpoise side can be small. The applies with a "medium
>> impedance" design as discussed earlier, but it applies even more for a
>> resonant end-fed with its tiny feed current. A short piece of wire may be
>> used, but often not even that is needed, as the feed return current may
>> flow
>> on the transformer and feedline (if used), and even on the radio box. This
>> is fine for QRP and maybe even medium power, as the current is small
>> relative to the higher current higher up on the wire. However, at medium
>> to
>> high power, if matching problems are encountered, or bothersome RF around
>> the rig, I would consider a small counterpoise wire to the high impedance
>> side of the transformer, or experimenting with the length of the feedline,
>> as the length of it matters when "counterpoise current" flows on the
>> outside
>> of it. I would not count on the impedance transformer to function as a
>> common mode choke for blocking such RF current. You could place a separate
>> common mode choke somewhere on the feedline, and move its position as a
>> way
>> to adjust the length of the effective counterpoise. Look up Jim's article
>> on
>> how to build an effective common mode choke.
>>
>> 73,
>> Erik K7TV
>>
>> -Original Message-
>> From: elecraft-boun...@mailman.qth.net
>> [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of JT Croteau
>> Sent: Saturday, November 18, 2017 2:34 PM
>> To: elecraft@mailman.qth.net
>> Subject: [Elecraft] KX3 Field Ant. for 80/40/30
>>
>> Friends, what would be a good end fed wire setup that will match well with
>> the internal KX3 ATU and cover, hopefully, 80, 40, and 30 meters?
>>
>> I went out to my winter camp site, with two really tall pine trees, and
>> tried to experiment with a 9:1 UNUN, 135' radiator, and 35' of RG8X.  It
>> was
>> a total disaster.  Best matches were on 20, 17, and 15 meters but only
>> with
>> 6.4:1 SWR.  No match at all on the lower bands.
>> With my two trees, the radiator made for a perfect inverted-L shape.
>>
>> What should I try next?  I did try some pruning of the antenna but quickly
>> gave up due to the WX conditions.
>>
>> Thanks
>> N1ESE
>> __
>> Elecraft mailing list
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>> delivered to ebasil...@cox.net
>>
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[Elecraft] KX3 Field Ant. for 80/40/30 Alternative to wire

[John Newgas]

I've used a narrow steel surveyor's tape as antenna.   You can get them quite 
cheaply on Amazon etc and they have  two advantages - they roll up very neatly 
and have the length of the antenna clearly written as you pull them out.  It is 
easy to solder little bit of flexible wire for connections onto where the 
buckle rivets on


G7LTQ - John N
From: Don Wilhelm <donw...@embarqmail.com>
Subject: Re: [Elecraft] KX3 Field Ant. for 80/40/30
Date: 18 November 2017 at 22:05:22 GMT
To: JT Croteau <jt.to...@gmail.com>, elecraft@mailman.qth.net
Reply-To: donw...@embarqmail.com


The easiest end fed antenna for portable use with those bands on the KX2/KX3 
comes from some experiments and experience of one of the KX2 field testers (and 
an active SOTA ham).
Use a BNC to dual binding post (Pomona) adapter on the KX2/3.  Connect a 58 
foot piece of wire to the red (center conductor) post, and a 23 foot 
"counterpoise" wire to the black (shield) post.  The counterpoise wire can be 
run along the ground or laying on top of nearby bushes.
Tie a rock or other throwing item to the end of the 58 foot radiator and get it 
up in the air - TUNE it and operate.
No balun, no fuss, and the wire rolls up into a small ball for transport.





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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Igor Sokolov]

r a
resonant end-fed with its tiny feed current. A short piece of wire may be
used, but often not even that is needed, as the feed return current may flow
on the transformer and feedline (if used), and even on the radio box. This
is fine for QRP and maybe even medium power, as the current is small
relative to the higher current higher up on the wire. However, at medium to
high power, if matching problems are encountered, or bothersome RF around
the rig, I would consider a small counterpoise wire to the high impedance
side of the transformer, or experimenting with the length of the feedline,
as the length of it matters when "counterpoise current" flows on the outside
of it. I would not count on the impedance transformer to function as a
common mode choke for blocking such RF current. You could place a separate
common mode choke somewhere on the feedline, and move its position as a way
to adjust the length of the effective counterpoise. Look up Jim's article on
how to build an effective common mode choke.

73,
Erik K7TV

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of JT Croteau
Sent: Saturday, November 18, 2017 2:34 PM
To: elecraft@mailman.qth.net
Subject: [Elecraft] KX3 Field Ant. for 80/40/30

Friends, what would be a good end fed wire setup that will match well with
the internal KX3 ATU and cover, hopefully, 80, 40, and 30 meters?

I went out to my winter camp site, with two really tall pine trees, and
tried to experiment with a 9:1 UNUN, 135' radiator, and 35' of RG8X.  It was
a total disaster.  Best matches were on 20, 17, and 15 meters but only with
6.4:1 SWR.  No match at all on the lower bands.
With my two trees, the radiator made for a perfect inverted-L shape.

What should I try next?  I did try some pruning of the antenna but quickly
gave up due to the WX conditions.

Thanks
N1ESE
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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Erik Basilier]

 even that is needed, as the feed return current may flow
on the transformer and feedline (if used), and even on the radio box. This
is fine for QRP and maybe even medium power, as the current is small
relative to the higher current higher up on the wire. However, at medium to
high power, if matching problems are encountered, or bothersome RF around
the rig, I would consider a small counterpoise wire to the high impedance
side of the transformer, or experimenting with the length of the feedline,
as the length of it matters when "counterpoise current" flows on the outside
of it. I would not count on the impedance transformer to function as a
common mode choke for blocking such RF current. You could place a separate
common mode choke somewhere on the feedline, and move its position as a way
to adjust the length of the effective counterpoise. Look up Jim's article on
how to build an effective common mode choke.

73,
Erik K7TV

-Original Message-
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of JT Croteau
Sent: Saturday, November 18, 2017 2:34 PM
To: elecraft@mailman.qth.net
Subject: [Elecraft] KX3 Field Ant. for 80/40/30

Friends, what would be a good end fed wire setup that will match well with
the internal KX3 ATU and cover, hopefully, 80, 40, and 30 meters?

I went out to my winter camp site, with two really tall pine trees, and
tried to experiment with a 9:1 UNUN, 135' radiator, and 35' of RG8X.  It was
a total disaster.  Best matches were on 20, 17, and 15 meters but only with
6.4:1 SWR.  No match at all on the lower bands.
With my two trees, the radiator made for a perfect inverted-L shape.

What should I try next?  I did try some pruning of the antenna but quickly
gave up due to the WX conditions.

Thanks
N1ESE
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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Jim Brown]

Check out the expedition that W6GJB, W6JTI, and I did for 7QP last year 
(2016) to seven NV counties, including Nye and Lander.   k9yc.com/7QP.pdf


73, Jim K9YC

On 11/18/2017 4:52 PM, Fred Jensen wrote:
Nearest "town" for me in Nye County is Gabbs, population 269, about 
2.5 hrs from home.  I'm way too old and way too physically diminished 
to do this without reasonable accommodations.  Google Nye County NV 
and pick Wikipedia for a photo of "downtown" Gabbs.  Between home and 
Gabbs is a whole lot of Basin and Range and no people. Might consider 
Lander Co from Battle Mountain however. 



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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Fred Jensen]

Nearest "town" for me in Nye County is Gabbs, population 269, about 2.5 
hrs from home.  I'm way too old and way too physically diminished to do 
this without reasonable accommodations.  Google Nye County NV and pick 
Wikipedia for a photo of "downtown" Gabbs.  Between home and Gabbs is a 
whole lot of Basin and Range and no people.  Might consider Lander Co 
from Battle Mountain however.


73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 11/18/2017 3:45 PM, Terry wrote:

Why not do Nye county as well. That might only take one QSO.  hi-hi

Terry, KQ5U


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[Elecraft] KX3 Field Ant. for 80/40/30

[Terry]

Why not do Nye county as well. That might only take one QSO.  hi-hi

Terry, KQ5U


On 11/18/2017 4:29 PM, Fred Jensen wrote:
My HOA-Stealth antenna is the "80-10 EF" from myantennas.com  It is 
strung on electric fence insulators along the top of the wooden fence, 
about 1.8 meters high.  It has a 90 deg bend in it about 1/3 of the 
way down from the transformer.  It actually works 160-10 with my 
K3/100 + KAT3.  It works surprisingly well, so much so that I bought a 
second to take on county expeditions in the 7QP contest.  I took First 
in Pershing County this year with ~350 CW-only Q's.  While that is 
also "Last in Pershing County," that is not indicated on the 
certificate. [:-)  Next year I may be First in Lander County, who knows?


Usual Disclaimer:  No financial interest in the company

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 11/18/2017 1:34 PM, JT Croteau wrote:

Friends, what would be a good end fed wire setup that will match well
with the internal KX3 ATU and cover, hopefully, 80, 40, and 30 meters?

I went out to my winter camp site, with two really tall pine trees,
and tried to experiment with a 9:1 UNUN, 135' radiator, and 35' of
RG8X.  It was a total disaster.  Best matches were on 20, 17, and 15
meters but only with 6.4:1 SWR.  No match at all on the lower bands.
With my two trees, the radiator made for a perfect inverted-L shape.

What should I try next?  I did try some pruning of the antenna but
quickly gave up due to the WX conditions.

Thanks
N1ESE



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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Fred Jensen]

My HOA-Stealth antenna is the "80-10 EF" from myantennas.com  It is 
strung on electric fence insulators along the top of the wooden fence, 
about 1.8 meters high.  It has a 90 deg bend in it about 1/3 of the way 
down from the transformer.  It actually works 160-10 with my K3/100 + 
KAT3.  It works surprisingly well, so much so that I bought a second to 
take on county expeditions in the 7QP contest.  I took First in Pershing 
County this year with ~350 CW-only Q's.  While that is also "Last in 
Pershing County," that is not indicated on the certificate. [:-)  Next 
year I may be First in Lander County, who knows?


Usual Disclaimer:  No financial interest in the company

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 11/18/2017 1:34 PM, JT Croteau wrote:

Friends, what would be a good end fed wire setup that will match well
with the internal KX3 ATU and cover, hopefully, 80, 40, and 30 meters?

I went out to my winter camp site, with two really tall pine trees,
and tried to experiment with a 9:1 UNUN, 135' radiator, and 35' of
RG8X.  It was a total disaster.  Best matches were on 20, 17, and 15
meters but only with 6.4:1 SWR.  No match at all on the lower bands.
With my two trees, the radiator made for a perfect inverted-L shape.

What should I try next?  I did try some pruning of the antenna but
quickly gave up due to the WX conditions.

Thanks
N1ESE



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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Jim Brown]

Yes, this is also a great technique. One suggestion though -- there's RF 
current in the counterpoise, and having it too close to the ground will 
burn (waste) some TX power. Better to run it in the range of 6-8 ft.


Remember - an SWR indication at the rig is NOT an indicator of antenna 
performance.  It only tells us that the transmitter is matched to 
whatever is connected to its terminals, but it tells us nothing about 
how much power is LOST in the feedline, the antenna, or the ground, nor 
does it tell us how well the antenna radiates or in what directions 
(vertically and horizontally) it radiates.


73, Jim K9YC

On 11/18/2017 2:05 PM, Don Wilhelm wrote:
The easiest end fed antenna for portable use with those bands on the 
KX2/KX3 comes from some experiments and experience of one of the KX2 
field testers (and an active SOTA ham).
Use a BNC to dual binding post (Pomona) adapter on the KX2/3. Connect 
a 58 foot piece of wire to the red (center conductor) post, and a 23 
foot "counterpoise" wire to the black (shield) post.  The counterpoise 
wire can be run along the ground or laying on top of nearby bushes.
Tie a rock or other throwing item to the end of the 58 foot radiator 
and get it up in the air - TUNE it and operate.

No balun, no fuss, and the wire rolls up into a small ball for transport.

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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Erlend Grimseid]

Hi.
Feet is not my everyday system for length measure, but i think it
transelate to very close to an full wave length on 40m and close to an half
wave on 80. That is an tough match for any tuner. Even so,  with the
transformer and the coax I think it should have given better results than
6.4:1 on most bands.

Did you have an choke between the coax and the radio/tuner? That might be
worth a try.  Also I would look for malfunction somewhere.

BUT. To answer your question. My go to antenna for the lower bands is an
simple dublet, feed with some old army field telephone  wire. It's an
twisted pair of multi strand wire. I belive it has four strands of copper,
ant three stainless steel, but I might be mistaken. The dublet is 2x20 (
aprox) meters. Might be worth a try.

La4tta Erlend



18. nov. 2017 10:37 p.m. skrev "JT Croteau" :

Friends, what would be a good end fed wire setup that will match well
with the internal KX3 ATU and cover, hopefully, 80, 40, and 30 meters?

I went out to my winter camp site, with two really tall pine trees,
and tried to experiment with a 9:1 UNUN, 135' radiator, and 35' of
RG8X.  It was a total disaster.  Best matches were on 20, 17, and 15
meters but only with 6.4:1 SWR.  No match at all on the lower bands.
With my two trees, the radiator made for a perfect inverted-L shape.

What should I try next?  I did try some pruning of the antenna but
quickly gave up due to the WX conditions.

Thanks
N1ESE
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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[JT Croteau]

Thanks Don, I will try this next.

On Sat, Nov 18, 2017 at 5:05 PM, Don Wilhelm  wrote:
> The easiest end fed antenna for portable use with those bands on the KX2/KX3
> comes from some experiments and experience of one of the KX2 field testers
> (and an active SOTA ham).
> Use a BNC to dual binding post (Pomona) adapter on the KX2/3.  Connect a 58
> foot piece of wire to the red (center conductor) post, and a 23 foot
> "counterpoise" wire to the black (shield) post.  The counterpoise wire can
> be run along the ground or laying on top of nearby bushes.
> Tie a rock or other throwing item to the end of the 58 foot radiator and get
> it up in the air - TUNE it and operate.
> No balun, no fuss, and the wire rolls up into a small ball for transport.
>
> 73,
> Don W3FPR
>
>
> On 11/18/2017 4:34 PM, JT Croteau wrote:
>>
>> Friends, what would be a good end fed wire setup that will match well
>> with the internal KX3 ATU and cover, hopefully, 80, 40, and 30 meters?
>>
>> I went out to my winter camp site, with two really tall pine trees,
>> and tried to experiment with a 9:1 UNUN, 135' radiator, and 35' of
>> RG8X.  It was a total disaster.  Best matches were on 20, 17, and 15
>> meters but only with 6.4:1 SWR.  No match at all on the lower bands.
>> With my two trees, the radiator made for a perfect inverted-L shape.
>>
>
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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Jim Brown]

On 11/18/2017 1:34 PM, JT Croteau wrote:

Friends, what would be a good end fed wire setup that will match well
with the internal KX3 ATU and cover, hopefully, 80, 40, and 30 meters?

I went out to my winter camp site, with two really tall pine trees,
and tried to experiment with a 9:1 UNUN, 135' radiator, and 35' of
RG8X.


The ARRL Handbook and ARRL Antenna Book are your friend. If you don't 
own them, RUN to your computer and buy one, new or used.


The short answer to your question is that, in general, end-fed wires 
need a counterpoise to work well. For your situation, I'd build two 
end-fed center-fed dipoles, one for 80 and one for 40, launch one into 
one of the trees, the second into the other tree. 75 ohm coax is the 
best match to these antennas, but 50 ohm coax will work. The following 
slide show describes this technique, beginning on slide #70.


http://k9yc.com/VerticalHeight.pdf

If possible, rig your dipoles so that they slope away from the tree(s) 
in which they are mounted. Anecdotal reports, and my limited experience, 
say that trees absorb a bit of the RF from a wire very close to their 
trunk. I suggest that you pull both antennas up as high as practical.


If for some reason you don't want to rig a dipole like this, pull a 
quarter wave wire for both bands into those trees and rig a quarter-wave 
counterpoise for each that's at least 6-8 ft above ground. If a feedline 
is needed, use RG8X with a good common mode choke but no transformer.


73, Jim K9YC

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Re: [Elecraft] KX3 Field Ant. for 80/40/30

[Don Wilhelm]

The easiest end fed antenna for portable use with those bands on the 
KX2/KX3 comes from some experiments and experience of one of the KX2 
field testers (and an active SOTA ham).
Use a BNC to dual binding post (Pomona) adapter on the KX2/3.  Connect a 
58 foot piece of wire to the red (center conductor) post, and a 23 foot 
"counterpoise" wire to the black (shield) post.  The counterpoise wire 
can be run along the ground or laying on top of nearby bushes.
Tie a rock or other throwing item to the end of the 58 foot radiator and 
get it up in the air - TUNE it and operate.

No balun, no fuss, and the wire rolls up into a small ball for transport.

73,
Don W3FPR

On 11/18/2017 4:34 PM, JT Croteau wrote:

Friends, what would be a good end fed wire setup that will match well
with the internal KX3 ATU and cover, hopefully, 80, 40, and 30 meters?

I went out to my winter camp site, with two really tall pine trees,
and tried to experiment with a 9:1 UNUN, 135' radiator, and 35' of
RG8X.  It was a total disaster.  Best matches were on 20, 17, and 15
meters but only with 6.4:1 SWR.  No match at all on the lower bands.
With my two trees, the radiator made for a perfect inverted-L shape.


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[Elecraft] KX3 Field Ant. for 80/40/30

[JT Croteau]

Friends, what would be a good end fed wire setup that will match well
with the internal KX3 ATU and cover, hopefully, 80, 40, and 30 meters?

I went out to my winter camp site, with two really tall pine trees,
and tried to experiment with a 9:1 UNUN, 135' radiator, and 35' of
RG8X.  It was a total disaster.  Best matches were on 20, 17, and 15
meters but only with 6.4:1 SWR.  No match at all on the lower bands.
With my two trees, the radiator made for a perfect inverted-L shape.

What should I try next?  I did try some pruning of the antenna but
quickly gave up due to the WX conditions.

Thanks
N1ESE
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