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KX3 ATU

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va3bxg

KX3 ATU

Does anyone know what the capability/efficiency of the internal ATU is?

Not talking about the wattage (its up to 20 I believe) but the tuning the SWR/range

Looking at deploying a random wire/loop so I am wondering if I need a separate ATU or can the internal unit handle the range?
Thanks
Robert

a 'kosher' ham
Sent from my BlackBerry device
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Don Wilhelm-4

Re: KX3 ATU

Robert,

The matching range should be similar to that of the K3 ATU. The actual
range can only be correctly expressed in terms of the inductance and
capacitance ranges and the number of steps for each - the SWR that
produces will vary from band to and will be least on the low frequencies
and greatest on the higher bands.

73,
Don W3FPR

On 4/24/2012 8:50 AM, [hidden email] wrote:
> Does anyone know what the capability/efficiency of the internal ATU is?
>
> Not talking about the wattage (its up to 20 I believe) but the tuning the SWR/range
>
> Looking at deploying a random wire/loop so I am wondering if I need a separate ATU or can the internal unit handle the range?
> Thanks
> Robert
>
>
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Niel Wiegand

Re: KX3 ATU

In reply to this post by va3bxg

Robert,

I've found that the KX3 ATU loads up a 58' endfed wire just fine on all
bands, but it can't load up everything. The 67' endfed wire I have
(which, in theory, is very tough to load up) could be loaded up on 20
with the K1 ATU. The KX3 ATU can not handle it.

So, for your loop, depending on the size, you may or may not have
trouble depending on the length. For a closed loop I believe you want to
avoid odd multiples of half wave lengths. If the possible length you
have is pretty inflexible and the KX3 ATU can't handle it you can try
inserting an insulator half way around making it an open loop.

73,
Niel - W0VLZ
KX3 #43

> Message: 21
> Date: Tue, 24 Apr 2012 12:50:28 +0000
> From:[hidden email]
> Subject: [Elecraft] KX3 ATU
> To: "Elecraft"<[hidden email]>
>
>
> Does anyone know what the capability/efficiency of the internal ATU is?
>
> Not talking about the wattage (its up to 20 I believe) but the tuning the SWR/range
>
> Looking at deploying a random wire/loop so I am wondering if I need a separate ATU or can the internal unit handle the range?
> Thanks
> Robert
>
> a 'kosher' ham
> Sent from my BlackBerry device

wayne burdick

Re: KX3 ATU

Administrator

67' is very close to a half-wave on 40 m and a full-wave on 20 m. In
theory the SWR should be insanely high, so I'm surprised the K1 ATU
handled it on 20 m. Even if it did, the losses would be very high.
Best to use lengths that aren't close to a multiple of a half-wave on
any target band.

Wayne
N6KR

On Apr 24, 2012, at 10:11 AM, Niel Wiegand wrote:

> Robert,
>
> I've found that the KX3 ATU loads up a 58' endfed wire just fine on
> all
> bands, but it can't load up everything. The 67' endfed wire I have
> (which, in theory, is very tough to load up) could be loaded up on 20
> with the K1 ATU. The KX3 ATU can not handle it.
>
> So, for your loop, depending on the size, you may or may not have
> trouble depending on the length. For a closed loop I believe you
> want to
> avoid odd multiples of half wave lengths. If the possible length you
> have is pretty inflexible and the KX3 ATU can't handle it you can try
> inserting an insulator half way around making it an open loop.
>
> 73,
> Niel - W0VLZ
> KX3 #43
>
>> Message: 21
>> Date: Tue, 24 Apr 2012 12:50:28 +0000
>> From:[hidden email]
>> Subject: [Elecraft] KX3 ATU
>> To: "Elecraft"<[hidden email]>
>>
>>
>> Does anyone know what the capability/efficiency of the internal ATU
>> is?
>>
>> Not talking about the wattage (its up to 20 I believe) but the
>> tuning the SWR/range
>>
>> Looking at deploying a random wire/loop so I am wondering if I need
>> a separate ATU or can the internal unit handle the range?
>> Thanks
>> Robert
>>
>> a 'kosher' ham
>> Sent from my BlackBerry device
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

wayne burdick

Re: KX3 ATU

Administrator

Just to clarify: I'm referring to *end-fed* antennas that are a
multiple of 1/2-wave. The feedpoint impedance of such antennas is
extremely high, something like 3-6 Kohms.

A 1/2-wave dipole or inverted V, fed in the middle, will typically be
50-75 ohms.

Wayne
N6KR

On Apr 24, 2012, at 1:08 PM, Wayne Burdick wrote:

> 67' is very close to a half-wave on 40 m and a full-wave on 20 m. In
> theory the SWR should be insanely high, so I'm surprised the K1 ATU
> handled it on 20 m. Even if it did, the losses would be very high.
> Best to use lengths that aren't close to a multiple of a half-wave on
> any target band.
>
> Wayne
> N6KR
>
> On Apr 24, 2012, at 10:11 AM, Niel Wiegand wrote:
>
>> Robert,
>>
>> I've found that the KX3 ATU loads up a 58' endfed wire just fine on
>> all
>> bands, but it can't load up everything. The 67' endfed wire I have
>> (which, in theory, is very tough to load up) could be loaded up on
>> 20
>> with the K1 ATU. The KX3 ATU can not handle it.
>>
>> So, for your loop, depending on the size, you may or may not have
>> trouble depending on the length. For a closed loop I believe you
>> want to
>> avoid odd multiples of half wave lengths. If the possible length you
>> have is pretty inflexible and the KX3 ATU can't handle it you can try
>> inserting an insulator half way around making it an open loop.
>>
>> 73,
>> Niel - W0VLZ
>> KX3 #43
>>
>>> Message: 21
>>> Date: Tue, 24 Apr 2012 12:50:28 +0000
>>> From:[hidden email]
>>> Subject: [Elecraft] KX3 ATU
>>> To: "Elecraft"<[hidden email]>
>>>
>>>
>>> Does anyone know what the capability/efficiency of the internal ATU
>>> is?
>>>
>>> Not talking about the wattage (its up to 20 I believe) but the
>>> tuning the SWR/range
>>>
>>> Looking at deploying a random wire/loop so I am wondering if I need
>>> a separate ATU or can the internal unit handle the range?
>>> Thanks
>>> Robert
>>>
>>> a 'kosher' ham
>>> Sent from my BlackBerry device
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
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Michael Babineau-2

Re: KX3 ATU

In reply to this post by va3bxg

Niel / Robert :

For what it is worth, 86 feet (i.e 26.5 m) is the ideal length of end-fed wire for matching via an auto tuner to cover the HF bands.
It is a "magic length" that isn't close to a multiple of a half wave on any of the HF bands (with perhaps the exception of 10m)
so it presents a reasonable impedance that can be matched by most ATUs across the HF spectrum. As Eric mentioned,
you want to stay away from lengths that are close to a half wave multiple on the bands that you want to operate as the wire will
present a very high impedance that is difficult to match with any ATU.

Not surprisingly, this length is not far off of the length of wire used for the W3EDP antenna (84 feet).

Michael VE3WMB

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vk4tux

Re: KX3 ATU

In reply to this post by va3bxg

Don, When you say "The ATU will tune the antenna to an acceptable SWR", you are contradicting yourself, because as you rightly said the tuner does not change the antenna feedpoint swr.

So we tune the transceiver to the feedline length feeding the antenna. that feedline length is important
regarding the 'measured' swr. A 1/2 wl will show the antenna feedpoint swr or impedance (with analyser).
At the connection to the transceiver before any builtin or ext tuner. The indicated swr on the transceiver or ext tuner display shows the feed side of the tuner swr.

In theory the swr along the feedline maintains value, but it's a very different story when you measure it.
The 1/2 wl feedline connected to a high swr antenna feedpoint shows high swr at the tx feedline end, but cut the feedline at the 1/4wl point and measure there for a much different 'indicated' result.

As the swr detectors in the transceiver or atu use this method also, it becomes obvious that feedline/coax length becomes a factor in showing the transceiver a good match when the antenna feedpoint impedance is other than 50 ohms..

The best thing you can do in a multiband antenna setups where antenna feedpoint impedance gets way off desired on certain bands, is to use the lowest loss feedline possible., because this is where most of your losses are, not the tuner. Remember only resistance can lose power as heat, not reactance.

Every signal pass back up and down the feedline until sync radiation release occurs, loses power with every pass depending on the feedline specifications.

>
Lucia,

The Elecraft tuner (I don't care if it is a KAT2, KAT1, KXT1 o KXAT3)
cannot change the the SWR of the antenna itself. The ATU will tune the
antenna to an acceptable SWR so the PA transistor in the transceiver
are happy. If you measure the SWR between the Tuner and the antenna,
you will not see any change. The internal tuner does change the
impedance that is seen by the PA transistors, and that is the goal of
antenna tuners.

73,
Don W3FPR

>

Matt Maguire

Re: KX3 ATU

On 19/09/2012, at 2:48 PM, vk4tux <[hidden email]> wrote:

> Don, When you say "The ATU will tune the antenna to an acceptable SWR", you
> are contradicting yourself, because as you rightly said the tuner does not
> change the antenna feedpoint swr.

It is clear from the context that Don meant the ATU will tune (ie. match) the antenna *system* to the radio, where the antenna system consists of the ATU, antenna and connecting feedline considered as a single unit. This of course does not mean that the VSWR is 1:1 everywhere within that system.

The theory predicts that the measures VSWR will be constant along a *lossless* feedline. As you point out, practical feedlines do have losses. This will include I^2.R copper losses, but there can be losses from other sources as well, such as dielectric losses. Often such losses will be modelled as some sort of equivalent series resistance.

73, Matt VK2ACL
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vk4tux

Re: KX3 ATU

Matt, Of course I don't question Don's technical stature, however "tuning
the antenna" is a poor choice of explanation, and can give a false
impression to those weak on the subject. Adding 'system' would have been a
good move as you indicate. We tune where we measure.

-----Original Message-----
From: Matt Maguire [mailto:[hidden email]]
Sent: Wednesday, 19 September 2012 3:35 PM
To: vk4tux
Cc: [hidden email]
Subject: Re: [Elecraft] KX3 ATU

On 19/09/2012, at 2:48 PM, vk4tux <[hidden email]> wrote:

> Don, When you say "The ATU will tune the antenna to an acceptable
> SWR", you are contradicting yourself, because as you rightly said the
> tuner does not change the antenna feedpoint swr.

It is clear from the context that Don meant the ATU will tune (ie. match)
the antenna *system* to the radio, where the antenna system consists of the
ATU, antenna and connecting feedline considered as a single unit. This of
course does not mean that the VSWR is 1:1 everywhere within that system.

The theory predicts that the measures VSWR will be constant along a
*lossless* feedline. As you point out, practical feedlines do have losses.
This will include I^2.R copper losses, but there can be losses from other
sources as well, such as dielectric losses. Often such losses will be
modelled as some sort of equivalent series resistance.

73, Matt VK2ACL=

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David Gilbert

Re: KX3 ATU

That's pretty much picking nits, in my opinion. It doesn't really
matter whether you physically locate needed complex reactance at the
antenna or present it to the antenna via the transmission line physics
of a feedline ... the net result that exists at the antenna is exactly
the same (neglecting transmission line losses, of course) in either
case. The only relevant distinction I can see is that "tuning" more
accurately refers to bringing something to resonance rather than also
transforming it to a different load impedance, but that falls into the
category of useless semantics for me and I can give you all sorts of
examples where it would be next to impossible to distinguish
electrically where an antenna ends. The dividing line between an
antenna and the rest of the system is not at all as definitive as you
suggest, and pretending it is seems more likely to give a false
impression of how things really work than not.

73,
Dave AB7E

On 9/18/2012 11:52 PM, Adrian wrote:

> Matt, Of course I don't question Don's technical stature, however "tuning
> the antenna" is a poor choice of explanation, and can give a false
> impression to those weak on the subject. Adding 'system' would have been a
> good move as you indicate. We tune where we measure.
>
> -----Original Message-----
> From: Matt Maguire [mailto:[hidden email]]
> Sent: Wednesday, 19 September 2012 3:35 PM
> To: vk4tux
> Cc: [hidden email]
> Subject: Re: [Elecraft] KX3 ATU
>
>
> On 19/09/2012, at 2:48 PM, vk4tux <[hidden email]> wrote:
>
>> Don, When you say "The ATU will tune the antenna to an acceptable
>> SWR", you are contradicting yourself, because as you rightly said the
>> tuner does not change the antenna feedpoint swr.
> It is clear from the context that Don meant the ATU will tune (ie. match)
> the antenna *system* to the radio, where the antenna system consists of the
> ATU, antenna and connecting feedline considered as a single unit. This of
> course does not mean that the VSWR is 1:1 everywhere within that system.
>
> The theory predicts that the measures VSWR will be constant along a
> *lossless* feedline. As you point out, practical feedlines do have losses.
> This will include I^2.R copper losses, but there can be losses from other
> sources as well, such as dielectric losses. Often such losses will be
> modelled as some sort of equivalent series resistance.
>
> 73, Matt VK2ACL=
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>

vk4tux

Re: KX3 ATU

Whether you tune the antenna or the feedline source makes a big difference
to signal passes on the feed line,
and hence feed line loss. Put the tuner at the antenna feedpoint and you are
tuning the antenna.

There is no nit picking about it, as to avoid the misconception by one
showing a 1:1 vswr at the transceiver, using a tuner there doing his coax
loss calculations at that vswr will get an incorrect result, when vswr
between tuner and antenna feedpoint maybe 5:1 or more (for example).

Tuning is adjusting a point to whatever you wish, whether it be a guitar E
note, or vswr at that point in the system, it is an adjustment at the point
of measurement. You may tune to a 1.5:1 vswr on a particular type of antenna
due to more effective radiation pattern. Despite all of your blather the
only things that matter are effective radiation and feedline losses.

~~~~That's pretty much picking nits, in my opinion. It doesn't really
matter whether you physically locate needed complex reactance at the antenna
or present it to the antenna via the transmission line physics of a feedline
... the net result that exists at the antenna is exactly the same
(neglecting transmission line losses, of course) in either case. The only
relevant distinction I can see is that "tuning" more accurately refers to
bringing something to resonance rather than also transforming it to a
different load impedance, but that falls into the category of useless
semantics for me and I can give you all sorts of examples where it would be
next to impossible to distinguish electrically where an antenna ends. The
dividing line between an antenna and the rest of the system is not at all as
definitive as you suggest, and pretending it is seems more likely to give a
false impression of how things really work than not.

73,
Dave AB7E

On 9/18/2012 11:52 PM, Adrian wrote:

> Matt, Of course I don't question Don's technical stature, however
> "tuning the antenna" is a poor choice of explanation, and can give a
> false impression to those weak on the subject. Adding 'system' would
> have been a good move as you indicate. We tune where we measure.
>
> -----Original Message-----
> From: Matt Maguire [mailto:[hidden email]]
> Sent: Wednesday, 19 September 2012 3:35 PM
> To: vk4tux
> Cc: [hidden email]
> Subject: Re: [Elecraft] KX3 ATU
>
>
> On 19/09/2012, at 2:48 PM, vk4tux <[hidden email]> wrote:
>
>> Don, When you say "The ATU will tune the antenna to an acceptable
>> SWR", you are contradicting yourself, because as you rightly said the
>> tuner does not change the antenna feedpoint swr.
> It is clear from the context that Don meant the ATU will tune (ie.
> match) the antenna *system* to the radio, where the antenna system
> consists of the ATU, antenna and connecting feedline considered as a
> single unit. This of course does not mean that the VSWR is 1:1 everywhere

within that system.

>
> The theory predicts that the measures VSWR will be constant along a
> *lossless* feedline. As you point out, practical feedlines do have losses.
> This will include I^2.R copper losses, but there can be losses from
> other sources as well, such as dielectric losses. Often such losses
> will be modelled as some sort of equivalent series resistance.
>
> 73, Matt VK2ACL=
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net Please help support this email
> list: http://www.qsl.net/donate.html
>

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Fred Townsend

Re: KX3 ATU

In reply to this post by David Gilbert

David, remember becoming 'nit free' leads to becoming 'lice free'. You are
correct that 'tuning' may have something to with bringing the circuit into
resonance but the term 'tuning' has other meanings too. For instance if we
equate tuning as bringing into resonance then we could not use the term
'tuning' applied to non-resonate antennas. You see the term is more
frequently applied to impedance matching and band centering.
Matching at the antenna is quite different than matching at transmitter.
Transmission lines are only pure transmission lines if they are matched at
both ends. If either end is mismatched the transmission line becomes a
circuit element. A transmission line inverts the reactance every quarter
wave. Hence R+jx becomes the complex conjugate R-jx after a quarter wave in
length. This increase the effects of frequency change requiring more
frequent retuning across the band. The higher the VSWR the higher the copper
losses in the coax. You seem to dismiss copper losses as being
insignificant. The higher the mismatch the more significant they become so
those losses can be saved if the match occurs at the antenna.
If you want to run your own little proof experiment take your favorite coax
feed antenna and measure and note the SWR at the transmitter. Make sure
there is a high SWR to measure like your 40 meter doublet running an 80
meters. Then add a long length of same impedance coax in series, say a 100',
and re-measure the SWR at the transmitter. The SWR will usually be much
different because of the additional attention from the longer coax.
73
Fred, AE6QL

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of David Gilbert
Sent: Wednesday, September 19, 2012 1:10 AM
To: [hidden email]
Subject: Re: [Elecraft] KX3 ATU

That's pretty much picking nits, in my opinion. It doesn't really matter
whether you physically locate needed complex reactance at the antenna or
present it to the antenna via the transmission line physics of a feedline
... the net result that exists at the antenna is exactly the same
(neglecting transmission line losses, of course) in either case. The only
relevant distinction I can see is that "tuning" more accurately refers to
bringing something to resonance rather than also transforming it to a
different load impedance, but that falls into the category of useless
semantics for me and I can give you all sorts of examples where it would be
next to impossible to distinguish electrically where an antenna ends. The
dividing line between an antenna and the rest of the system is not at all as
definitive as you suggest, and pretending it is seems more likely to give a
false impression of how things really work than not.

73,
Dave AB7E

On 9/18/2012 11:52 PM, Adrian wrote:

within that system.
>
> The theory predicts that the measures VSWR will be constant along a
> *lossless* feedline. As you point out, practical feedlines do have losses.
> This will include I^2.R copper losses, but there can be losses from
> other sources as well, such as dielectric losses. Often such losses
> will be modelled as some sort of equivalent series resistance.
>
> 73, Matt VK2ACL=

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F5LCI

Re: KX3 ATU

In reply to this post by va3bxg

Do not forget to take with you a 4/1 balun (like the BL-2) : it can help, even if the KX3 ATU already can tune a wider impedance range than the so-called ATUs inside the YIK rigs.
At my present DX QTH (BH91nv), where I could not anticipate the antenna possibilities, I have no problem with a 10 m whip and a xxx ohms open wire line.
Regards,
JeanMarc, FO/F5LCI

Sent from my KX3 :-)

David Gilbert

Re: KX3 ATU

In reply to this post by Fred Townsend

You are misled on several points:

1. I never tried to restrict the term "tuning" to only bringing
something to resonance. I merely was allowing for the sensibilities of
those who may think it was being used too loosely where other terms
might be more accurate ... such as the term "matching" would be in the
case where impedances differed. Reread the part where I said that I
considered such distinctions to be useless semantics.

2. I know exactly how transmission lines operate and that is why I say
there is no difference in terms of where or how an antenna is "tuned" or
"matched" ... it can be done at the antenna or in the shack and
(discounting feedline losses) the net electrical effect at the antenna
is exactly the same. Whether doing so results in a narrower response is
immaterial to the discussion of whether or not the term "tuning" can
only be accurately applied at the antenna. Go back and read the earlier
messages in this thread if you are confused on what the discussion is
about ... at least from the point at which I entered it.

3. I'm not in any way dismissing losses in the feedline due to SWR as
being unimportant. They are of course a significant factor to be
considered when deciding where to perform the tuning and/or matching
function. Those losses do not, however, have anything to do with
whether or not performing those functions in the shack constitutes
"tuning the antenna".

73,
Dave AB7E

On 9/19/2012 1:20 PM, Fred Townsend wrote:

> David, remember becoming 'nit free' leads to becoming 'lice free'. You are
> correct that 'tuning' may have something to with bringing the circuit into
> resonance but the term 'tuning' has other meanings too. For instance if we
> equate tuning as bringing into resonance then we could not use the term
> 'tuning' applied to non-resonate antennas. You see the term is more
> frequently applied to impedance matching and band centering.
> Matching at the antenna is quite different than matching at transmitter.
> Transmission lines are only pure transmission lines if they are matched at
> both ends. If either end is mismatched the transmission line becomes a
> circuit element. A transmission line inverts the reactance every quarter
> wave. Hence R+jx becomes the complex conjugate R-jx after a quarter wave in
> length. This increase the effects of frequency change requiring more
> frequent retuning across the band. The higher the VSWR the higher the copper
> losses in the coax. You seem to dismiss copper losses as being
> insignificant. The higher the mismatch the more significant they become so
> those losses can be saved if the match occurs at the antenna.
> If you want to run your own little proof experiment take your favorite coax
> feed antenna and measure and note the SWR at the transmitter. Make sure
> there is a high SWR to measure like your 40 meter doublet running an 80
> meters. Then add a long length of same impedance coax in series, say a 100',
> and re-measure the SWR at the transmitter. The SWR will usually be much
> different because of the additional attention from the longer coax.
> 73
> Fred, AE6QL
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of David Gilbert
> Sent: Wednesday, September 19, 2012 1:10 AM
> To: [hidden email]
> Subject: Re: [Elecraft] KX3 ATU
>
>
> That's pretty much picking nits, in my opinion. It doesn't really matter
> whether you physically locate needed complex reactance at the antenna or
> present it to the antenna via the transmission line physics of a feedline
> ... the net result that exists at the antenna is exactly the same
> (neglecting transmission line losses, of course) in either case. The only
> relevant distinction I can see is that "tuning" more accurately refers to
> bringing something to resonance rather than also transforming it to a
> different load impedance, but that falls into the category of useless
> semantics for me and I can give you all sorts of examples where it would be
> next to impossible to distinguish electrically where an antenna ends. The
> dividing line between an antenna and the rest of the system is not at all as
> definitive as you suggest, and pretending it is seems more likely to give a
> false impression of how things really work than not.
>
> 73,
> Dave AB7E
>
>
>
> On 9/18/2012 11:52 PM, Adrian wrote:
>> Matt, Of course I don't question Don's technical stature, however
>> "tuning the antenna" is a poor choice of explanation, and can give a
>> false impression to those weak on the subject. Adding 'system' would
>> have been a good move as you indicate. We tune where we measure.
>>
>> -----Original Message-----
>> From: Matt Maguire [mailto:[hidden email]]
>> Sent: Wednesday, 19 September 2012 3:35 PM
>> To: vk4tux
>> Cc: [hidden email]
>> Subject: Re: [Elecraft] KX3 ATU
>>
>>
>> On 19/09/2012, at 2:48 PM, vk4tux <[hidden email]> wrote:
>>
>>> Don, When you say "The ATU will tune the antenna to an acceptable
>>> SWR", you are contradicting yourself, because as you rightly said the
>>> tuner does not change the antenna feedpoint swr.
>> It is clear from the context that Don meant the ATU will tune (ie.
>> match) the antenna *system* to the radio, where the antenna system
>> consists of the ATU, antenna and connecting feedline considered as a
>> single unit. This of course does not mean that the VSWR is 1:1 everywhere
> within that system.
>> The theory predicts that the measures VSWR will be constant along a
>> *lossless* feedline. As you point out, practical feedlines do have losses.
>> This will include I^2.R copper losses, but there can be losses from
>> other sources as well, such as dielectric losses. Often such losses
>> will be modelled as some sort of equivalent series resistance.
>>
>> 73, Matt VK2ACL=
>
>

Ignacy

Re: KX3 ATU

Time to finish kindergarten activities.

ATU in my KX3 has trouble tuning. I matched few bands and was loosing lock during a QSO. Small changes in antenna length caused it to have large changes in matching. I became very critical of ATU it especially that it all took place during my trip to a few countries in EU.

Elecraft sent ATU replacement and now everything is fine. ATU in KX3 is now a good deal.
Ignacy