KX2 Antenna Curiosity

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KX2 Antenna Curiosity

Elecraft mailing list
I have had my KX2 with the ATU for about 10 months and operate on 40m QRP SSB from various locations.  Experimenting with different antennas I have experienced best results with a 58.5’ wire tossed about 25’ up a tree with a 16.5’ counterpoise.  I ran the same length wire from my house to the workshop, grounded the shield side of the cable, and have seen similar results to the field setup.  

Is there some engineering/design factor of the KX2 for this type of antenna setup?  I am planning to setup a Dipole at home, but as a newbie am wondering if the “ideal” Ham Dipole can be expected to improve performance.

Keeping Watch-
shu

Joe Shuman
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Re: KX2 Antenna Curiosity

David Gilbert

Your field antenna is essentially a very low off-center fed sloped
dipole slightly longer than a half wavelength.  I'm not surprised you
can tune it with the KX2, but it certainly isn't any kind of ideal
antenna configuration that Elecraft would design for.  They just made a
very well performing tuner for the KX2 that will work with almost
anything.  I have a KX2 ... it's amazing what it can tune.

You didn't say how long your feedline is, but with a feed that far off
center the shield of your coax is probably doing some of the radiating
anyway.

Yes, a center fed normal dipole with the middle (high current portion)
higher off the ground (say 50 feet for 40m) and a common mode choke at
the feedpoint would almost assuredly perform better. If you can't get it
that high, a vertical (even a 30 foot wire oriented mostly straight up)
fed against a decent radial system might be a better choice if you don't
have a lot of surrounding buildings/trees/telephone poles.

For the record, I also have on rare occasions used low sloped wires fed
near one end against some sort of ground or counterpoise when camping or
for a hurried Field Day setup.  They are easy to set up and sort of
work, but they always performed very poorly compared to even the most
basic dipole if I could get the dipole off the ground approaching a half
wavelength in height.  Over the years I have operated roughly 20 Field
Day contests (almost always 5 watts CW for the extra QRP points) and one
year I used only a low sloped wire similar to what you described.  It
was memorable for being the worst Field Day result I have ever had, and
that's in spite of the fact that I've placed top 3 nationwide in my
category on more than one occasion using only wire antennas strung from
tall trees.

73,
Dave   AB7E



On 10/10/2019 9:01 AM, Joseph Shuman via Elecraft wrote:
> I have had my KX2 with the ATU for about 10 months and operate on 40m QRP SSB from various locations.  Experimenting with different antennas I have experienced best results with a 58.5’ wire tossed about 25’ up a tree with a 16.5’ counterpoise.  I ran the same length wire from my house to the workshop, grounded the shield side of the cable, and have seen similar results to the field setup.
>
> Is there some engineering/design factor of the KX2 for this type of antenna setup?  I am planning to setup a Dipole at home, but as a newbie am wondering if the “ideal” Ham Dipole can be expected to improve performance.
>
> Keeping Watch-
> shu
>
> Joe Shuman

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Re: KX2 Antenna Curiosity

Tim McDonough N9PUZ
In reply to this post by Elecraft mailing list
If you are talking about a single band dipole then any half wave dipole cut
to the standard formula and fed with good quality coax should work well. If
you want a "multi band" dipole then I would recommend cutting it for the
lowest frequency you plan to operate and feeding it with balanced line.
Even the best coax can have a lot of loss under high SWR conditions
(between your tuner and the antenna feedpoint) whereas even at 1 10:1 SWR
balanced line does not have much loss. The radiation pattern of a multi
band configuration can vary a lot from band to band.

The end fed wire you describe is not specific to the KX2. You typically
want the longest wire possible that is NOT a half wavelength or even
multiple on any band you want to operate. The main reason for this is when
a wire is a half wave or an even multiple the impedance at the end of the
wire can be very high and it is more difficult for most tuners to obtain a
match there. By it NOT being a half wave, the impedance is lower and a wide
range tuner like the one in your KX2 can match it more easily and present
the proper impedance to the radio.

Here is an article that suggests good lengths for a "random wire" antenna.
The lengths aren't really very random, they are specifically chosen to be
easier to match. At 58.5 feet you arrived at one of the good lengths.

<https://udel.edu/~mm/ham/randomWire/>

Tim N9PUZ

On Thu, Oct 10, 2019 at 11:03 AM Joseph Shuman via Elecraft <
[hidden email]> wrote:

> I have had my KX2 with the ATU for about 10 months and operate on 40m QRP
> SSB from various locations.  Experimenting with different antennas I have
> experienced best results with a 58.5’ wire tossed about 25’ up a tree with
> a 16.5’ counterpoise.  I ran the same length wire from my house to the
> workshop, grounded the shield side of the cable, and have seen similar
> results to the field setup.
>
> Is there some engineering/design factor of the KX2 for this type of
> antenna setup?  I am planning to setup a Dipole at home, but as a newbie am
> wondering if the “ideal” Ham Dipole can be expected to improve performance.
>
> Keeping Watch-
> shu
>
> Joe Shuman
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
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Re: KX2 Antenna Curiosity

Don Wilhelm
In reply to this post by Elecraft mailing list
Shu,

If you add the 58.5 foot wire to the 16.5' counterpoise, you have a 75
foot antenna.  That is close to a half wavelength on 40 meters.  You are
feeding it off-center which will allow it to be used on several bands
(even though one of the antenna wires is on the ground).
As I recall, Bruce Prior (one of the KX2 Field Testers) recommended
those lengths for 40 meters thru 10 meters.
If you feed those 2 wires directly from the KX2 tuner using a BNC to
binding post adapter, you do not have to worry about feedline loss -
there is no feedline!
If you do use a feedline, I suggest ladder line rather than coax because
it will not have as much loss in the feedline due to an impedance mismatch.

The KX2/KX3/K3 ATUs have a very wide matching range and this antenna
will work fine with any of their tuners.

73,
Don W3FPR

On 10/10/2019 12:01 PM, Joseph Shuman via Elecraft wrote:
> I have had my KX2 with the ATU for about 10 months and operate on 40m QRP SSB from various locations.  Experimenting with different antennas I have experienced best results with a 58.5’ wire tossed about 25’ up a tree with a 16.5’ counterpoise.  I ran the same length wire from my house to the workshop, grounded the shield side of the cable, and have seen similar results to the field setup.
>
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Re: KX2 Antenna Curiosity

Grant Youngman-2
In reply to this post by Tim McDonough N9PUZ
Absolutely.  The other advantage of a horizontal dipole (or inverted V) is that it will be far quieter than the wire.

An end fed non-resonant wire installed as a sort-of sloper “works” but is far from optimum.  Especially since you’re using a minimal counterpoise system.  One counterpoise wire (elevated) is far from being optimum.  But sure, you can make contacts on one.

That said, we all deal with what we have available.  As someone else said, a resonant vertical with an adequate radial system will work very well, too, if you have the space.  A vertical will be good for DX,  So will a dipole at a 1/2 wave up.  The dipole at lower heights (or an inverted V if you can’t hang it high from both ends) will be far better for local to medium range contacts than the vertical.  It depends on your objectives.

I’ve been experimenting with this same kind of non-resonant end-fed wire antenna on 20M because in my living situation it is supposedly good for multi band operation.  It works poorly everywhere.  My 20M Buddipole vertical (with 4 elevated radials) works better than that wire.  I recently got a 20M horizontal antenna bent around in my restricted space, and it is so much quieter, and works well, too.

I’d also suggest a thorough reading of the ARRL Antenna Book if you haven’t done so :-)

Grant NQ5T
KX3 (8342)/KXPA100


> On Oct 10, 2019, at 2:59 PM, Tim N9PUZ <[hidden email]> wrote:
>
> If you are talking about a single band dipole then any half wave dipole cut
> to the standard formula and fed with good quality coax should work well. <snip>
>
>>  I am planning to setup a Dipole at home, but as a newbie am
>> wondering if the “ideal” Ham Dipole can be expected to improve performance.
>>

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Center-fed antennas

alorona
In reply to this post by David Gilbert
My experience with single vertical or sloping wires is exactly the same as AB7E's. I have, over almost twice as many Field Days as Dave, come to a similar conclusion, with the slight difference being my preference for an "all-band dipole" fed with balanced line. This obviates the balun and reduces feedline loss to negligible, so obviously I am maximizing efficiency at the expense of any other possible advantage. (I can usually hear much better than I can be heard... so thus far this has been a valid decision.)

To sum up what I and what I think Dave are saying, you can't beat a horizontal, center-fed wire up as high as you can get it. Its simplicity, the flexibility it gives you to QSY (with a good tuner), and its high efficiency are almost unbeatable.

As a side note, the center-fed horizontal wire I have used here at home is totally non-resonant. I don't even know how long it is. Once you give up the obsession with resonant antenna length, you gain a huge freedom of choice.

In the bottom of the sunspot cycle, these advantages are somewhat reduced because an op, especially on Field Day, might opt to forget about any band higher than 20 meters -- and these days even 20 is questionable. This means you can probably make do with coaxial cable and a balun for operation on 2 or 3 bands but the general idea still holds.

Al  W6LX


>Yes, a center fed normal dipole with the middle (high current portion)
>higher off the ground (say 50 feet for 40m) and a common mode choke at
>the feedpoint would almost assuredly perform better.
>
>73,
>Dave   AB7E
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Re: Center-fed antennas

Lyn WØLEN
I'm having great success with a horizontal center-fed "dipole" that has been sized (360 feet long) to be an Extended Double Zepp (4.7 dbi gain) and cut for the low end of 80 meters.  I feed it with 600 ohm "True" Ladder Line from a Balun Designs Hybrid Balun (1:1 Current and 4:1 Voltage all in one case).  A short run of coax from the balun to my KAT500, and I am in business at any frequency on 160 - 6 meters.

It's oriented to be an effective NVIS radiator in a N-S pattern on 80m, by design, and to have major lobes on the other bands in other directions - also by design.  For me, it's the most efficient and effective way to utilize our lot space (400 feet clear) and still be "under the radar" in our HOA.

Birds seem to like it, and I find that it seems to be especially attractive to Hummingbirds, my XYL's favorites.  A win-win, in my book.

73
Lyn, WØLEN


-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Al Lorona
Sent: Thursday, October 10, 2019 3:25 PM
To: [hidden email]; David Gilbert
Subject: [Elecraft] Center-fed antennas

My experience with single vertical or sloping wires is exactly the same as AB7E's. I have, over almost twice as many Field Days as Dave, come to a similar conclusion, with the slight difference being my preference for an "all-band dipole" fed with balanced line. This obviates the balun and reduces feedline loss to negligible, so obviously I am maximizing efficiency at the expense of any other possible advantage. (I can usually hear much better than I can be heard... so thus far this has been a valid decision.)

To sum up what I and what I think Dave are saying, you can't beat a horizontal, center-fed wire up as high as you can get it. Its simplicity, the flexibility it gives you to QSY (with a good tuner), and its high efficiency are almost unbeatable.

As a side note, the center-fed horizontal wire I have used here at home is totally non-resonant. I don't even know how long it is. Once you give up the obsession with resonant antenna length, you gain a huge freedom of choice.

In the bottom of the sunspot cycle, these advantages are somewhat reduced because an op, especially on Field Day, might opt to forget about any band higher than 20 meters -- and these days even 20 is questionable. This means you can probably make do with coaxial cable and a balun for operation on 2 or 3 bands but the general idea still holds.

Al  W6LX


>Yes, a center fed normal dipole with the middle (high current portion)
>higher off the ground (say 50 feet for 40m) and a common mode choke at
>the feedpoint would almost assuredly perform better.
>
>73,
>Dave   AB7E
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Re: Center-fed antennas

k6dgw
In reply to this post by alorona
Yes, however ... a center-fed dipole long enough to be moderately close
to a half-wave at 40 will develop a serious case of acute lobe-itis when
operated at higher frequencies, squirting your RF in a variety of
directions, many of which may not be productive for your intended
objective.  Try, as many have over the years, to design the "magic
antenna" that is very small, provides a 1:1 match on all bands, easily
installed, and exhibits good gain, your effort will inevitably fail.  As
JC Maxwell is reported to have said, "Physics is physics, the rules are
unbreakable."  A log-periodic will give very modest gain over an octave
or more, however LP's hardly fall into the Field Antenna class. [:-)

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 10/10/2019 1:24 PM, Al Lorona wrote:

> My experience with single vertical or sloping wires is exactly the same as AB7E's. I have, over almost twice as many Field Days as Dave, come to a similar conclusion, with the slight difference being my preference for an "all-band dipole" fed with balanced line. This obviates the balun and reduces feedline loss to negligible, so obviously I am maximizing efficiency at the expense of any other possible advantage. (I can usually hear much better than I can be heard... so thus far this has been a valid decision.)
>
> To sum up what I and what I think Dave are saying, you can't beat a horizontal, center-fed wire up as high as you can get it. Its simplicity, the flexibility it gives you to QSY (with a good tuner), and its high efficiency are almost unbeatable.
>
> As a side note, the center-fed horizontal wire I have used here at home is totally non-resonant. I don't even know how long it is. Once you give up the obsession with resonant antenna length, you gain a huge freedom of choice.
>
> In the bottom of the sunspot cycle, these advantages are somewhat reduced because an op, especially on Field Day, might opt to forget about any band higher than 20 meters -- and these days even 20 is questionable. This means you can probably make do with coaxial cable and a balun for operation on 2 or 3 bands but the general idea still holds.
>
> Al  W6LX
>

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Re: Center-fed antennas

David Lee
On Thu, Oct 10, 2019 at 2:06 PM Fred Jensen <[hidden email]> wrote:

> Yes, however ... a center-fed dipole long enough to be moderately close
> to a half-wave at 40 will develop a serious case of acute lobe-itis when
> operated at higher frequencies, squirting your RF in a variety of
> directions, many of which may not be productive for your intended
> objective.  Try, as many have over the years, to design the "magic
> antenna" that is very small, provides a 1:1 match on all bands, easily
> installed, and exhibits good gain, your effort will inevitably fail.  As
> JC Maxwell is reported to have said, "Physics is physics, the rules are
> unbreakable."  A log-periodic will give very modest gain over an octave
> or more, however LP's hardly fall into the Field Antenna class. [:-)
>
> 73,
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
>
> On 10/10/2019 1:24 PM, Al Lorona wrote:
> > My experience with single vertical or sloping wires is exactly the same
> as AB7E's. I have, over almost twice as many Field Days as Dave, come to a
> similar conclusion, with the slight difference being my preference for an
> "all-band dipole" fed with balanced line. This obviates the balun and
> reduces feedline loss to negligible, so obviously I am maximizing
> efficiency at the expense of any other possible advantage. (I can usually
> hear much better than I can be heard... so thus far this has been a valid
> decision.)
> >
> > To sum up what I and what I think Dave are saying, you can't beat a
> horizontal, center-fed wire up as high as you can get it. Its simplicity,
> the flexibility it gives you to QSY (with a good tuner), and its high
> efficiency are almost unbeatable.
> >
> > As a side note, the center-fed horizontal wire I have used here at home
> is totally non-resonant. I don't even know how long it is. Once you give up
> the obsession with resonant antenna length, you gain a huge freedom of
> choice.
> >
> > In the bottom of the sunspot cycle, these advantages are somewhat
> reduced because an op, especially on Field Day, might opt to forget about
> any band higher than 20 meters -- and these days even 20 is questionable.
> This means you can probably make do with coaxial cable and a balun for
> operation on 2 or 3 bands but the general idea still holds.
> >
> > Al  W6LX
> >
>
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Re: Center-fed antennas

Don Wilhelm
All this talk of multi-band antennas for Field Day ignores the problem
of multi-station Field Day operation.
There is sufficient pickup of one transmitter's energy on the antenna
being used by a receiver on another band.
For that reason, my club has banned the use of multiband antennas for
Field Day operation.

For a single station Field Day operation, the multiband antennas are great.

73,
Don W3FPR

On 10/10/2019 5:32 PM, David Lee / Seatools wrote:

> On Thu, Oct 10, 2019 at 2:06 PM Fred Jensen <[hidden email]> wrote:
>
>> Yes, however ... a center-fed dipole long enough to be moderately close
>> to a half-wave at 40 will develop a serious case of acute lobe-itis when
>> operated at higher frequencies, squirting your RF in a variety of
>> directions, many of which may not be productive for your intended
>> objective.  Try, as many have over the years, to design the "magic
>> antenna" that is very small, provides a 1:1 match on all bands, easily
>> installed, and exhibits good gain, your effort will inevitably fail.  As
>> JC Maxwell is reported to have said, "Physics is physics, the rules are
>> unbreakable."  A log-periodic will give very modest gain over an octave
>> or more, however LP's hardly fall into the Field Antenna class. [:-)
>>
>> 73,
>> Fred ["Skip"] K6DGW
>> Sparks NV DM09dn
>> Washoe County
>>
>> On 10/10/2019 1:24 PM, Al Lorona wrote:
>>> My experience with single vertical or sloping wires is exactly the same
>> as AB7E's. I have, over almost twice as many Field Days as Dave, come to a
>> similar conclusion, with the slight difference being my preference for an
>> "all-band dipole" fed with balanced line. This obviates the balun and
>> reduces feedline loss to negligible, so obviously I am maximizing
>> efficiency at the expense of any other possible advantage. (I can usually
>> hear much better than I can be heard... so thus far this has been a valid
>> decision.)
>>>
>>> To sum up what I and what I think Dave are saying, you can't beat a
>> horizontal, center-fed wire up as high as you can get it. Its simplicity,
>> the flexibility it gives you to QSY (with a good tuner), and its high
>> efficiency are almost unbeatable.
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Re: Center-fed antennas

alorona
In reply to this post by k6dgw
Precisely because of this objection and countless others, is why I expressly stated, "...at the expense of any other possible advantage." I think we all understand that there's no magic antenna. The 'magic' of the antenna we're discussing here is simplicity, all-frequency operation, and high efficiency. No other magical claims are being made.

Al  W6LX

>Yes, however ... a center-fed dipole long enough to be moderately close
>to a half-wave at 40 will develop a serious case of acute lobe-itis when
>operated at higher frequencies



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Center-fed antennas

Ken G Kopp
In reply to this post by Don Wilhelm
Well-said, Don.

73!

Ken Kopp - K0PP

On Thu, Oct 10, 2019, 16:23 Don Wilhelm <[hidden email]> wrote:

> All this talk of multi-band antennas for Field Day ignores the problem
> of multi-station Field Day operation.
> There is sufficient pickup of one transmitter's energy on the antenna
> being used by a receiver on another band.
> For that reason, my club has banned the use of multiband antennas for
> Field Day operation.
>
> For a single station Field Day operation, the multiband antennas are great.
>
> 73,
> Don W3FPR
>
> On 10/10/2019 5:32 PM, David Lee / Seatools wrote:
> > On Thu, Oct 10, 2019 at 2:06 PM Fred Jensen <[hidden email]> wrote:
> >
> >> Yes, however ... a center-fed dipole long enough to be moderately close
> >> to a half-wave at 40 will develop a serious case of acute lobe-itis when
> >> operated at higher frequencies, squirting your RF in a variety of
> >> directions, many of which may not be productive for your intended
> >> objective.  Try, as many have over the years, to design the "magic
> >> antenna" that is very small, provides a 1:1 match on all bands, easily
> >> installed, and exhibits good gain, your effort will inevitably fail.  As
> >> JC Maxwell is reported to have said, "Physics is physics, the rules are
> >> unbreakable."  A log-periodic will give very modest gain over an octave
> >> or more, however LP's hardly fall into the Field Antenna class. [:-)
> >>
> >> 73,
> >> Fred ["Skip"] K6DGW
> >> Sparks NV DM09dn
> >> Washoe County
> >>
> >> On 10/10/2019 1:24 PM, Al Lorona wrote:
> >>> My experience with single vertical or sloping wires is exactly the same
> >> as AB7E's. I have, over almost twice as many Field Days as Dave, come
> to a
> >> similar conclusion, with the slight difference being my preference for
> an
> >> "all-band dipole" fed with balanced line. This obviates the balun and
> >> reduces feedline loss to negligible, so obviously I am maximizing
> >> efficiency at the expense of any other possible advantage. (I can
> usually
> >> hear much better than I can be heard... so thus far this has been a
> valid
> >> decision.)
> >>>
> >>> To sum up what I and what I think Dave are saying, you can't beat a
> >> horizontal, center-fed wire up as high as you can get it. Its
> simplicity,
> >> the flexibility it gives you to QSY (with a good tuner), and its high
> >> efficiency are almost unbeatable.
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Re: Center-fed antennas

Bob McGraw - K4TAX
I thought a Band Pass Filter at each station resolved that issue.

73

Bob, K4TAX

On 10/10/2019 5:27 PM, Ken G Kopp wrote:

> Well-said, Don.
>
> 73!
>
> Ken Kopp - K0PP
>
> On Thu, Oct 10, 2019, 16:23 Don Wilhelm <[hidden email]> wrote:
>
>> All this talk of multi-band antennas for Field Day ignores the problem
>> of multi-station Field Day operation.
>> There is sufficient pickup of one transmitter's energy on the antenna
>> being used by a receiver on another band.
>> For that reason, my club has banned the use of multiband antennas for
>> Field Day operation.
>>
>> For a single station Field Day operation, the multiband antennas are great.
>>
>> 73,
>> Don W3FPR
>>
>> On 10/10/2019 5:32 PM, David Lee / Seatools wrote:
>>> On Thu, Oct 10, 2019 at 2:06 PM Fred Jensen <[hidden email]> wrote:
>>>
>>>> Yes, however ... a center-fed dipole long enough to be moderately close
>>>> to a half-wave at 40 will develop a serious case of acute lobe-itis when
>>>> operated at higher frequencies, squirting your RF in a variety of
>>>> directions, many of which may not be productive for your intended
>>>> objective.  Try, as many have over the years, to design the "magic
>>>> antenna" that is very small, provides a 1:1 match on all bands, easily
>>>> installed, and exhibits good gain, your effort will inevitably fail.  As
>>>> JC Maxwell is reported to have said, "Physics is physics, the rules are
>>>> unbreakable."  A log-periodic will give very modest gain over an octave
>>>> or more, however LP's hardly fall into the Field Antenna class. [:-)
>>>>
>>>> 73,
>>>> Fred ["Skip"] K6DGW
>>>> Sparks NV DM09dn
>>>> Washoe County
>>>>
>>>> On 10/10/2019 1:24 PM, Al Lorona wrote:
>>>>> My experience with single vertical or sloping wires is exactly the same
>>>> as AB7E's. I have, over almost twice as many Field Days as Dave, come
>> to a
>>>> similar conclusion, with the slight difference being my preference for
>> an
>>>> "all-band dipole" fed with balanced line. This obviates the balun and
>>>> reduces feedline loss to negligible, so obviously I am maximizing
>>>> efficiency at the expense of any other possible advantage. (I can
>> usually
>>>> hear much better than I can be heard... so thus far this has been a
>> valid
>>>> decision.)
>>>>> To sum up what I and what I think Dave are saying, you can't beat a
>>>> horizontal, center-fed wire up as high as you can get it. Its
>> simplicity,
>>>> the flexibility it gives you to QSY (with a good tuner), and its high
>>>> efficiency are almost unbeatable.
>> ______________________________________________________________
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Re: Center-fed antennas

Rick WA6NHC-2
In reply to this post by Lyn WØLEN
I have over 200 countries on a similar antenna, though I had to use
another tuner than the KAT500, for 160M. Average height was about 35'.

Just keep the coax short, like under 10' and as much center fed wire as
you can put in the air, it'll play.  It won't rock your world, it'll
make you work for some of the DX, but that teaches patience and
operating technique, still win-win.

Rick nhc


On 10/10/2019 1:56 PM, Lyn Norstad wrote:

> I'm having great success with a horizontal center-fed "dipole" that has been sized (360 feet long) to be an Extended Double Zepp (4.7 dbi gain) and cut for the low end of 80 meters.  I feed it with 600 ohm "True" Ladder Line from a Balun Designs Hybrid Balun (1:1 Current and 4:1 Voltage all in one case).  A short run of coax from the balun to my KAT500, and I am in business at any frequency on 160 - 6 meters.
>
> It's oriented to be an effective NVIS radiator in a N-S pattern on 80m, by design, and to have major lobes on the other bands in other directions - also by design.  For me, it's the most efficient and effective way to utilize our lot space (400 feet clear) and still be "under the radar" in our HOA.
>
> Birds seem to like it, and I find that it seems to be especially attractive to Hummingbirds, my XYL's favorites.  A win-win, in my book.
>
> 73
> Lyn, WØLEN
>
>
> -----Original Message-----
> From: [hidden email] [mailto:[hidden email]] On Behalf Of Al Lorona
> Sent: Thursday, October 10, 2019 3:25 PM
> To: [hidden email]; David Gilbert
> Subject: [Elecraft] Center-fed antennas
>
> My experience with single vertical or sloping wires is exactly the same as AB7E's. I have, over almost twice as many Field Days as Dave, come to a similar conclusion, with the slight difference being my preference for an "all-band dipole" fed with balanced line. This obviates the balun and reduces feedline loss to negligible, so obviously I am maximizing efficiency at the expense of any other possible advantage. (I can usually hear much better than I can be heard... so thus far this has been a valid decision.)
>
> To sum up what I and what I think Dave are saying, you can't beat a horizontal, center-fed wire up as high as you can get it. Its simplicity, the flexibility it gives you to QSY (with a good tuner), and its high efficiency are almost unbeatable.
>
> As a side note, the center-fed horizontal wire I have used here at home is totally non-resonant. I don't even know how long it is. Once you give up the obsession with resonant antenna length, you gain a huge freedom of choice.
>
> In the bottom of the sunspot cycle, these advantages are somewhat reduced because an op, especially on Field Day, might opt to forget about any band higher than 20 meters -- and these days even 20 is questionable. This means you can probably make do with coaxial cable and a balun for operation on 2 or 3 bands but the general idea still holds.
>
> Al  W6LX
>
>
>> Yes, a center fed normal dipole with the middle (high current portion)
>> higher off the ground (say 50 feet for 40m) and a common mode choke at
>> the feedpoint would almost assuredly perform better.
>>
>> 73,
>> Dave   AB7E
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Re: Center-fed antennas

Don Wilhelm
In reply to this post by Bob McGraw - K4TAX
Bob,

Bandpass filters at each station will help a lot, but they do not have
infinite out of band rejection.
There is still a huge benefit with single band antennas.  My club uses both.

Last Field Day (3F operation) one station got on the air with a
multiband vertical, and all other operators jumped on that operator to
shut him down quickly!  The multi-band antenna radiated harmonics of the
radio.  Even though the transmitter met the -43 dB harmonic required by
the FCC, the proximity of the multiband antenna to other antennas caused
problems (that station was not using a bandpass filter).

So for Field Day multi-station operation, single band antennas, bandpass
filters and transmitters with low phase noise are important.  We were
not able to orient the antennas end to end due to space considerations
at the EOC site, so we had to compromise on that, which makes the other
factors very important.

I need to point out that as an experiment, a 2nd station used an antenna
on 20 meters separated from the main 20 meters, and we were able to
operate one on CW (K3) at the same time as the other station (Icom) used
digital and SSB modes.  We had some mutual interference, but it was
minimal.  The K3 did not interfere much with the Icom due to the K3's
low phase noise, but the Icom did raise the background noise level on
the K3.

73,
Don W3FPR

On 10/10/2019 7:12 PM, Bob McGraw K4TAX wrote:

> I thought a Band Pass Filter at each station resolved that issue.
>
> 73
>
> Bob, K4TAX
>
> On 10/10/2019 5:27 PM, Ken G Kopp wrote:
>> Well-said, Don.
>>
>> 73!
>>
>> Ken Kopp - K0PP
>>
>> On Thu, Oct 10, 2019, 16:23 Don Wilhelm <[hidden email]> wrote:
>>
>>> All this talk of multi-band antennas for Field Day ignores the problem
>>> of multi-station Field Day operation.
>>> There is sufficient pickup of one transmitter's energy on the antenna
>>> being used by a receiver on another band.
>>> For that reason, my club has banned the use of multiband antennas for
>>> Field Day operation.
>>>
>>> For a single station Field Day operation, the multiband antennas are
>>> great.
>>>
>>> 73,
>>> Don W3FPR
>>>
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Re: Center-fed antennas

alorona
Fair enough, but it kinda goes without saying that in a group FD with 1 station per band they'll use resonant, single-band antennas. If this is our best argument against the 'multiband dipole', then that antenna still holds its own pretty well in a multitude of other situations.

I have always found a deep resistance and opposition to this antenna. Whether it's an unwillingness to use antenna tuners, which many hams have, or an undue fear of noise, which some hams have, or a belief that open-wire line is noisier/weirder/harder/impossible-to-go-through-walls, which many hams believe, the visceral reaction against this antenna always amazes and baffles me.

Please forgive my belligerence... the Dodgers lost and I've been in a sour mood all day.

Al  W6LX
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Re: Center-fed antennas

Joe Subich, W4TV-4
In reply to this post by Don Wilhelm

The one "multiband" antenna one can use in a multi-transmitter
configuration is the flat-top with open wire feeders and a
*Link coupled* tuner.  The link coupled tuner is a bandpass filter
that significantly reduces harmonic/broadband noise just like the
"Q" of a single band antenna.

73,

    ... Joe, W4TV


On 2019-10-10 7:44 PM, Don Wilhelm wrote:

> Bob,
>
> Bandpass filters at each station will help a lot, but they do not have
> infinite out of band rejection.
> There is still a huge benefit with single band antennas.  My club uses
> both.
>
> Last Field Day (3F operation) one station got on the air with a
> multiband vertical, and all other operators jumped on that operator to
> shut him down quickly!  The multi-band antenna radiated harmonics of the
> radio.  Even though the transmitter met the -43 dB harmonic required by
> the FCC, the proximity of the multiband antenna to other antennas caused
> problems (that station was not using a bandpass filter).
>
> So for Field Day multi-station operation, single band antennas, bandpass
> filters and transmitters with low phase noise are important.  We were
> not able to orient the antennas end to end due to space considerations
> at the EOC site, so we had to compromise on that, which makes the other
> factors very important.
>
> I need to point out that as an experiment, a 2nd station used an antenna
> on 20 meters separated from the main 20 meters, and we were able to
> operate one on CW (K3) at the same time as the other station (Icom) used
> digital and SSB modes.  We had some mutual interference, but it was
> minimal.  The K3 did not interfere much with the Icom due to the K3's
> low phase noise, but the Icom did raise the background noise level on
> the K3.
>
> 73,
> Don W3FPR
>

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Re: Center-fed antennas

Elecraft mailing list
In reply to this post by Don Wilhelm
As usual, there are exceptions to everything. A multi-band beam, such as a C3S or the modern equivalent, will perform incredibly well when used with bandpass filters and a triplexer. The 10,15 and 20 meter stations all will use the antenna through the triplexer/BPFs with no issues. This also turns out to be a favorite setup for many SO2R and M/2 stations at both low and high power. The key is port-to-port isolation through the triplexer/BPFs. It is extremely important that all components can handle the power level in use. Also very important is that the radios have very low spurs and phase noise (i.e. need to have clean signals on transmit). The K3/K3S meets the bill, as do recent Flex Radio SDRs. As Rob Sherwood has pointed out recently, the transmit issue (See Oct QST and hi Dayton Contest Forum talk this past May) is pretty big in most radios. They have been paying attention to receiver issues, but not transmitter. We are very lucky that Wayne, Eric and friends have been p
 aying attention to this issue for many years.

73!
Jack, W6FB


> On Oct 10, 2019, at 4:44 PM, Don Wilhelm <[hidden email]> wrote:
>
> Bob,
>
> Bandpass filters at each station will help a lot, but they do not have infinite out of band rejection.
> There is still a huge benefit with single band antennas.  My club uses both.
>
> Last Field Day (3F operation) one station got on the air with a multiband vertical, and all other operators jumped on that operator to shut him down quickly!  The multi-band antenna radiated harmonics of the radio.  Even though the transmitter met the -43 dB harmonic required by the FCC, the proximity of the multiband antenna to other antennas caused problems (that station was not using a bandpass filter).
>
> So for Field Day multi-station operation, single band antennas, bandpass filters and transmitters with low phase noise are important.  We were not able to orient the antennas end to end due to space considerations at the EOC site, so we had to compromise on that, which makes the other factors very important.
>
> I need to point out that as an experiment, a 2nd station used an antenna on 20 meters separated from the main 20 meters, and we were able to operate one on CW (K3) at the same time as the other station (Icom) used digital and SSB modes.  We had some mutual interference, but it was minimal.  The K3 did not interfere much with the Icom due to the K3's low phase noise, but the Icom did raise the background noise level on the K3.
>
> 73,
> Don W3FPR
>
> On 10/10/2019 7:12 PM, Bob McGraw K4TAX wrote:
>> I thought a Band Pass Filter at each station resolved that issue.
>> 73
>> Bob, K4TAX
>> On 10/10/2019 5:27 PM, Ken G Kopp wrote:
>>> Well-said, Don.
>>>
>>> 73!
>>>
>>> Ken Kopp - K0PP
>>>
>>> On Thu, Oct 10, 2019, 16:23 Don Wilhelm <[hidden email]> wrote:
>>>
>>>> All this talk of multi-band antennas for Field Day ignores the problem
>>>> of multi-station Field Day operation.
>>>> There is sufficient pickup of one transmitter's energy on the antenna
>>>> being used by a receiver on another band.
>>>> For that reason, my club has banned the use of multiband antennas for
>>>> Field Day operation.
>>>>
>>>> For a single station Field Day operation, the multiband antennas are great.
>>>>
>>>> 73,
>>>> Don W3FPR
>>>>
> ______________________________________________________________
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Re: Center-fed antennas

Don Wilhelm
In reply to this post by Joe Subich, W4TV-4
Joe,

I agree completely, bring your Johnson Matchbox to the next Field Day!
Or even your old plug-in coil open frame link coupled balanced tuner.

Who has a link coupled tuner (like the Johnson Matchbox) these days?
Those are big boat anchor box these days (and hard to find).  I have one
that sees little use, but I am not willing to part with it.  It does a
good job when needed.

Most autotuners are of the L-network design and the manual tuners are
typically T-network - the L-network can be a high pass or a low pass
filter, but the more common T-network is always a high pass filter.  If
one has an old Collins tuner, it may be a Pi-network which is a low pass
filter.

As you pointed out, the link coupled tuner is a bandpass filter, but
fixed tune bandpass filters will do just as well for multi-station
operation.

73,
Don W3FPR

On 10/10/2019 7:57 PM, Joe Subich, W4TV wrote:

>
> The one "multiband" antenna one can use in a multi-transmitter
> configuration is the flat-top with open wire feeders and a
> *Link coupled* tuner.  The link coupled tuner is a bandpass filter
> that significantly reduces harmonic/broadband noise just like the
> "Q" of a single band antenna.
>
> 73,
>
>     ... Joe, W4TV
>
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Re: Center-fed antennas

ab4iqkf4cxo
In reply to this post by Don Wilhelm
At W4NJA (3A) for Field Day we use three Dipoles (Cut for the low end of 80
meters) fed with 450 Ohm ladder line into a DXEngineering Balun with less
than ten feet of coax into the rig.  The feed line is cut at odd multiples
and the antennas are spaced in a straight line end to end with separation of
course.  We can run three stations on the same band but different modes with
no interaction.  We used to use G5RV's, verticals, beams etc. but have opted
for this configuration because it works.  No problem with K3's, Omni VII's
tuners to tune the bands.  I have the actual length's that the three are cut
for but they are stored at another location.  I actually got the information
from DXEngineering somewhere on their web pages.

Ed.. AB4IQ

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Don Wilhelm
Sent: Thursday, October 10, 2019 6:44 PM
To: Bob McGraw K4TAX <[hidden email]>; [hidden email]
Subject: Re: [Elecraft] Center-fed antennas

Bob,

Bandpass filters at each station will help a lot, but they do not have
infinite out of band rejection.
There is still a huge benefit with single band antennas.  My club uses both.

Last Field Day (3F operation) one station got on the air with a multiband
vertical, and all other operators jumped on that operator to shut him down
quickly!  The multi-band antenna radiated harmonics of the radio.  Even
though the transmitter met the -43 dB harmonic required by the FCC, the
proximity of the multiband antenna to other antennas caused problems (that
station was not using a bandpass filter).

So for Field Day multi-station operation, single band antennas, bandpass
filters and transmitters with low phase noise are important.  We were not
able to orient the antennas end to end due to space considerations at the
EOC site, so we had to compromise on that, which makes the other factors
very important.

I need to point out that as an experiment, a 2nd station used an antenna on
20 meters separated from the main 20 meters, and we were able to operate one
on CW (K3) at the same time as the other station (Icom) used digital and SSB
modes.  We had some mutual interference, but it was minimal.  The K3 did not
interfere much with the Icom due to the K3's low phase noise, but the Icom
did raise the background noise level on the K3.

73,
Don W3FPR

On 10/10/2019 7:12 PM, Bob McGraw K4TAX wrote:

> I thought a Band Pass Filter at each station resolved that issue.
>
> 73
>
> Bob, K4TAX
>
> On 10/10/2019 5:27 PM, Ken G Kopp wrote:
>> Well-said, Don.
>>
>> 73!
>>
>> Ken Kopp - K0PP
>>
>> On Thu, Oct 10, 2019, 16:23 Don Wilhelm <[hidden email]> wrote:
>>
>>> All this talk of multi-band antennas for Field Day ignores the
>>> problem of multi-station Field Day operation.
>>> There is sufficient pickup of one transmitter's energy on the
>>> antenna being used by a receiver on another band.
>>> For that reason, my club has banned the use of multiband antennas
>>> for Field Day operation.
>>>
>>> For a single station Field Day operation, the multiband antennas are
>>> great.
>>>
>>> 73,
>>> Don W3FPR
>>>
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