Elecraft

Is a K3 ATU with balanced outputs possible?

Classic

List

Threaded

13 messages Options

Andrew Moore-3

Is a K3 ATU with balanced outputs possible?

I'd love to see a K3 built-in ATU with balanced outputs to feed "ladder"
line. Has this been considered and dismissed, or is it a possibility for a
future option?

I'm guessing this might be a problem for the already crowded rear panel,
but could it be provided as a plug-in board (like the KANT3 or the KAT3)
that uses the two antenna ports (ANT1, ANT2) for the two sides of the
ladder line, and does away with the SO239 altogether?

Failing that, could the functionality be provided in the KAT500?

Apologies if this has already been discussed; I haven't found much
discussion on it in the archives.

--Andrew, NV1B
maineware.net
..
______________________________________________________________
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

Don Wilhelm-4

Re: Is a K3 ATU with balanced outputs possible?

Andrew,

A bit of 'trivia' first:
That was "supposed" to be a solution in the KAT500 tuner. The initial
design put the balun on the input of the tuner, and attempted to "float"
the rest of the tuner while trying to maintain balance.

There were problems with maintaining balance through the rest of the
tuner, while studies indicated there was no efficiency difference
between the balun at the input vs. the balun at the output, so the
design was changed to an unbalanced design driving (if required or
desired) a balun at the output of the tuner.

"trivia off":

So more specific to your question, a balanced output from the K3 KAT3
can easily be obtained by using an Elecraft BL2 on the output side of
the KAT3.

73,
Don W3FPR

On 9/28/2012 6:22 PM, Andrew Moore wrote:

> I'd love to see a K3 built-in ATU with balanced outputs to feed "ladder"
> line. Has this been considered and dismissed, or is it a possibility for a
> future option?
>
> I'm guessing this might be a problem for the already crowded rear panel,
> but could it be provided as a plug-in board (like the KANT3 or the KAT3)
> that uses the two antenna ports (ANT1, ANT2) for the two sides of the
> ladder line, and does away with the SO239 altogether?
>
> Failing that, could the functionality be provided in the KAT500?
>
> Apologies if this has already been discussed; I haven't found much
> discussion on it in the archives.
>

______________________________________________________________
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

Andrew Moore-3

Re: Is a K3 ATU with balanced outputs possible?

Great; thank you for the trivia, very helpful. I figured it had already
been considered and that there was a good reason for the current
configuration.

The BL2 following the KAT3 was exactly one option I was considering. I've
read about several cases in which ops had success, but read others in which
the balun was heating perhaps due to excessive reactance on the antenna
side. Reactance is likely dependent on the frequency/band and several
factors in the antenna system which could explain the mixed results.

I think I will try this approach and enjoy the experimenting.

All: Not looking to turn this in to an OT antenna theory thread, but if you
have specific experience with this configuration, I'd like to hear (KAT3 to
BL2 to ladder to simple dipole).

Thanks,
--Andrew, NV1B
maineware.net
..

On Fri, Sep 28, 2012 at 6:43 PM, Don Wilhelm <[hidden email]> wrote:

> Andrew,
>
> A bit of 'trivia' first:
> That was "supposed" to be a solution in the KAT500 tuner. The initial
> design put the balun on the input of the tuner, and attempted to "float"
> the rest of the tuner while trying to maintain balance.
>
> There were problems with maintaining balance through the rest of the
> tuner, while studies indicated there was no efficiency difference between
> the balun at the input vs. the balun at the output, so the design was
> changed to an unbalanced design driving (if required or desired) a balun at
> the output of the tuner.
>
> "trivia off":
>
> So more specific to your question, a balanced output from the K3 KAT3 can
> easily be obtained by using an Elecraft BL2 on the output side of the KAT3.
>
>

Matt Maguire

Re: Is a K3 ATU with balanced outputs possible?

There may be no difference in efficiency between putting the balun at the input or the output of the tuner if you are operating into a nice 50ohm resistive dummy load, but the situation changes if you are operating into an antenna fed with ladder line on which there is a high SWR. In this case, the high SWR can cause high currents that saturate the ferrite core in the balun, and causing non-linearity and producing heat losses. This is why it may be preferable to locate the balun at the input of the tuner, where the SWR on the transmission line is low, and "float" the whole tuner. However, as Don mentioned, this can present difficulties if the tuner is not a balanced design.

73, Matt VK2ACL

On 29/09/2012, at 9:06 AM, Andrew Moore <[hidden email]> wrote:

> Great; thank you for the trivia, very helpful. I figured it had already
> been considered and that there was a good reason for the current
> configuration.
>
> The BL2 following the KAT3 was exactly one option I was considering. I've
> read about several cases in which ops had success, but read others in which
> the balun was heating perhaps due to excessive reactance on the antenna
> side. Reactance is likely dependent on the frequency/band and several
> factors in the antenna system which could explain the mixed results.
>
> I think I will try this approach and enjoy the experimenting.
>
> All: Not looking to turn this in to an OT antenna theory thread, but if you
> have specific experience with this configuration, I'd like to hear (KAT3 to
> BL2 to ladder to simple dipole).
>
> Thanks,
> --Andrew, NV1B
> maineware.net
> ..
>
>
> On Fri, Sep 28, 2012 at 6:43 PM, Don Wilhelm <[hidden email]> wrote:
>
>> Andrew,
>>
>> A bit of 'trivia' first:
>> That was "supposed" to be a solution in the KAT500 tuner. The initial
>> design put the balun on the input of the tuner, and attempted to "float"
>> the rest of the tuner while trying to maintain balance.
>>
>> There were problems with maintaining balance through the rest of the
>> tuner, while studies indicated there was no efficiency difference between
>> the balun at the input vs. the balun at the output, so the design was
>> changed to an unbalanced design driving (if required or desired) a balun at
>> the output of the tuner.
>>
>> "trivia off":
>>
>> So more specific to your question, a balanced output from the K3 KAT3 can
>> easily be obtained by using an Elecraft BL2 on the output side of the KAT3.
>>
>>
> ______________________________________________________________
> 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

Don Wilhelm-4

Re: Is a K3 ATU with balanced outputs possible?

In reply to this post by Andrew Moore-3

Andrew,

The BL2 on the output of the tuner may not be the total answer. The
conditions and situations are too numerous to address. I would suggest
some study into antennas and transmission lines before assuming that
"anything will work" - because it is not true that "anything will work".
The one thing I can say is that if you can make an antenna take a load,
that power will be radiated. Beyond that statement, I take no
responsibility for the specifics, it all depends on the particular
installation.

As one "for instance", attempting to feed the end of a 1/2 wavelength
wire will likely result in failure. The KAT3 is not designed to work
into a quite high impedance.

73.
Don W3FPR

On 9/28/2012 7:06 PM, Andrew Moore wrote:

Eric Buggee; VK3AX

Re: Is a K3 ATU with balanced outputs possible?

In reply to this post by Andrew Moore-3

Hi Andrew, Don & all,

I have a K3 (4520) and have recently installed a new antenna in the form
of a "V" beam with the bisector at about 7 Degrees east of North, with
the included angle at about 70 degrees and a leg length of 285Ft, height
above ground is 70 to 75 Ft, with ground sloping down away to N & NE for
20Km.

I have found that using the KAT3 in the K3 and a BL2 Balun it is useable
on all bands from 160 through to 6M with the worst VSWR of 1.5:1 showing
up on 160 at 1860KHz.

Reports from stations at, 1 to 5000 Km north from Emerald in the ranges
60 KM East of Melbourne in VK3 land give the "V" beam an advantage of 2
to 3 Sunits over the main antenna running NE to SW (A full sized 160M
dipole at 105Ft, fed with OW line spced 6inches) .

Reports run as follows:- 160M, generally 1 S unit down WR to the 160M
dipole;

80M, equal to & sometimes 1 S unit better (on average) compared to the
160 M dipole appears to be dependent upon time of day & prop'n conditions;

40M, definitely better with 1 to 2 S units better most of the time (day
or night);

30 M, definitely better by consistent 2 to 3 Sunits better at 3 to 5000Km;

20 M like 30 M consistently better than the 160 M dipole by 2 to 3 S
units at 3 to 5000Km distance.

The higher bands, with the V Beam I am hearing DX stations that are not
even detectable on the 160 M dipole (8 & 24MHz), but, so far no
definitive contacts made using the V beam to give a real evalution as
yet. It has only been operational for about 10 days.

Hope the foregoing is of interest,

73,

From Eric VK3AX.

On 9/29/2012 9:06 AM, Andrew Moore wrote:

Eric Buggee; VK3AX

Re: Is a K3 ATU with balanced outputs possible?

On 9/29/2012 10:04 AM, Eric Buggee wrote: Addendum to my original post.
> Hi Andrew, Don & all,
>
> I have a K3 (4520) and have recently installed a new antenna in the
> form of a "V" beam with the bisector at about 7 Degrees east of North,
> with the included angle at about 70 degrees and a leg length of 285Ft,
> height above ground is 70 to 75 Ft, with ground sloping down away to N
> & NE for 20Km.
" I should have added: the following".

" The feed line from the BL2 which is mounted under the eaves of the
shack with about 3M of RG58 to the K3.
From the BL2 at 10Ft above ground to the V beam I have a run of
73Ft of Ladder Line with 14Gauge Copperweld conductors."

>
> I have found that using the KAT3 in the K3 and the BL2 Balun it is
> useable on all bands from 160 through to 6M with the worst VSWR of
> 1.5:1 showing up on 160 at 1860KHz.
>
> Reports from stations at, 1 to 5000 Km north from Emerald in the
> ranges 60 KM East of Melbourne in VK3 land give the "V" beam an
> advantage of 2 to 3 Sunits over the main antenna running NE to SW (A
> full sized 160M dipole at 105Ft, fed with OW line spced 6inches) .
>
> Reports run as follows:- 160M, generally 1 S unit down WR to the 160M
> dipole;
>
> 80M, equal to & sometimes 1 S unit better (on average) compared to the
> 160 M dipole appears to be dependent upon time of day & prop'n
> conditions;
>
> 40M, definitely better with 1 to 2 S units better most of the time
> (day or night);
>
> 30 M, definitely better by consistent 2 to 3 Sunits better at 3 to
> 5000Km;
>
> 20 M like 30 M consistently better than the 160 M dipole by 2 to 3 S
> units at 3 to 5000Km distance.
>
> The higher bands, with the V Beam I am hearing DX stations that are
> not even detectable on the 160 M dipole (8 & 24MHz), but, so far no
> definitive contacts made using the V beam to give a real evalution as
> yet. It has only been operational for about 10 days.
>
> Hope the foregoing is of interest,
>
> 73,
>
> From Eric VK3AX.
>
>
>
> On 9/29/2012 9:06 AM, Andrew Moore wrote:
>> Great; thank you for the trivia, very helpful. I figured it had already
>> been considered and that there was a good reason for the current
>> configuration.
>>
>> The BL2 following the KAT3 was exactly one option I was considering.
>> I've
>> read about several cases in which ops had success, but read others in
>> which
>> the balun was heating perhaps due to excessive reactance on the antenna
>> side. Reactance is likely dependent on the frequency/band and several
>> factors in the antenna system which could explain the mixed results.
>>
>> I think I will try this approach and enjoy the experimenting.
>>
>> All: Not looking to turn this in to an OT antenna theory thread, but
>> if you
>> have specific experience with this configuration, I'd like to hear
>> (KAT3 to
>> BL2 to ladder to simple dipole).
>>
>> Thanks,
>> --Andrew, NV1B
>> maineware.net
>> ..
>>
>>
>> On Fri, Sep 28, 2012 at 6:43 PM, Don Wilhelm <[hidden email]>
>> wrote:
>>
>>> Andrew,
>>>
>>> A bit of 'trivia' first:
>>> That was "supposed" to be a solution in the KAT500 tuner. The initial
>>> design put the balun on the input of the tuner, and attempted to
>>> "float"
>>> the rest of the tuner while trying to maintain balance.
>>>
>>> There were problems with maintaining balance through the rest of the
>>> tuner, while studies indicated there was no efficiency difference
>>> between
>>> the balun at the input vs. the balun at the output, so the design was
>>> changed to an unbalanced design driving (if required or desired) a
>>> balun at
>>> the output of the tuner.
>>>
>>> "trivia off":
>>>
>>> So more specific to your question, a balanced output from the K3
>>> KAT3 can
>>> easily be obtained by using an Elecraft BL2 on the output side of
>>> the KAT3.
>>>
>>>
>> ______________________________________________________________
>> 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
>>
>

Don Wilhelm-4

Re: Is a K3 ATU with balanced outputs possible?

In reply to this post by Eric Buggee; VK3AX

Eric,

A "V" beam will be quite directional (bidirectional) and the response
depends on frequency. especially at those frequencies where the length
is in excess of 1 wavelength.

You must have found a good length if it operates well with the BL2 and
the KAT3 combination.
The wire angle of 70 degrees is good for 40 meters through 20 meters,
but is effective for other bands as well.

73,
Don W3FPR

On 9/28/2012 8:04 PM, Eric Buggee wrote:

> Hi Andrew, Don & all,
>
> I have a K3 (4520) and have recently installed a new antenna in the form
> of a "V" beam with the bisector at about 7 Degrees east of North, with
> the included angle at about 70 degrees and a leg length of 285Ft, height
> above ground is 70 to 75 Ft, with ground sloping down away to N & NE for
> 20Km.
>
> I have found that using the KAT3 in the K3 and a BL2 Balun it is useable
> on all bands from 160 through to 6M with the worst VSWR of 1.5:1 showing
> up on 160 at 1860KHz.
>
> Reports from stations at, 1 to 5000 Km north from Emerald in the ranges
> 60 KM East of Melbourne in VK3 land give the "V" beam an advantage of 2
> to 3 Sunits over the main antenna running NE to SW (A full sized 160M
> dipole at 105Ft, fed with OW line spced 6inches) .
>
> Reports run as follows:- 160M, generally 1 S unit down WR to the 160M
> dipole;
>
> 80M, equal to & sometimes 1 S unit better (on average) compared to the
> 160 M dipole appears to be dependent upon time of day & prop'n conditions;
>
> 40M, definitely better with 1 to 2 S units better most of the time (day
> or night);
>
> 30 M, definitely better by consistent 2 to 3 Sunits better at 3 to 5000Km;
>
> 20 M like 30 M consistently better than the 160 M dipole by 2 to 3 S
> units at 3 to 5000Km distance.
>
> The higher bands, with the V Beam I am hearing DX stations that are not
> even detectable on the 160 M dipole (8 & 24MHz), but, so far no
> definitive contacts made using the V beam to give a real evalution as
> yet. It has only been operational for about 10 days.
>
> Hope the foregoing is of interest,
>
> 73,
>
> From Eric VK3AX.
>
>
>
> On 9/29/2012 9:06 AM, Andrew Moore wrote:
>> Great; thank you for the trivia, very helpful. I figured it had already
>> been considered and that there was a good reason for the current
>> configuration.
>>
>> The BL2 following the KAT3 was exactly one option I was considering. I've
>> read about several cases in which ops had success, but read others in which
>> the balun was heating perhaps due to excessive reactance on the antenna
>> side. Reactance is likely dependent on the frequency/band and several
>> factors in the antenna system which could explain the mixed results.
>>
>> I think I will try this approach and enjoy the experimenting.
>>
>> All: Not looking to turn this in to an OT antenna theory thread, but if you
>> have specific experience with this configuration, I'd like to hear (KAT3 to
>> BL2 to ladder to simple dipole).
>>
>> Thanks,
>> --Andrew, NV1B
>> maineware.net
>> ..
>>
>>
>> On Fri, Sep 28, 2012 at 6:43 PM, Don Wilhelm <[hidden email]> wrote:
>>
>>> Andrew,
>>>
>>> A bit of 'trivia' first:
>>> That was "supposed" to be a solution in the KAT500 tuner. The initial
>>> design put the balun on the input of the tuner, and attempted to "float"
>>> the rest of the tuner while trying to maintain balance.
>>>
>>> There were problems with maintaining balance through the rest of the
>>> tuner, while studies indicated there was no efficiency difference between
>>> the balun at the input vs. the balun at the output, so the design was
>>> changed to an unbalanced design driving (if required or desired) a balun at
>>> the output of the tuner.
>>>
>>> "trivia off":
>>>
>>> So more specific to your question, a balanced output from the K3 KAT3 can
>>> easily be obtained by using an Elecraft BL2 on the output side of the KAT3.
>>>
>>>
>> ______________________________________________________________
>> 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
> 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
>

Nate Bargmann

Re: Is a K3 ATU with balanced outputs possible?

In reply to this post by Andrew Moore-3

* On 2012 28 Sep 18:07 -0500, Andrew Moore wrote:

> I think I will try this approach and enjoy the experimenting.

Hi Andrew.

For learning the theory on a lot of this stuff, a good reference on the
topic is Reflections III by Walt Maxwell, W2DU (SK), published by CQ
Communications. Walt did a very good job explaining the 'what' and 'why' on
impedance matching and also some gave some 'how' on dealing with it in a
practical manner. The book has its roots in a series of articles he
wrote in the '70s for QST titled, "Another Look at Reflections" and the
series can be found on the ARRL's QST archive. I have the first edition
but procrastinated and never got the second edition published by World
Radio, now owned by CQ.

73, de Nate, N0NB >>

--

"The optimist proclaims that we live in the best of all
possible worlds. The pessimist fears this is true."

Ham radio, Linux, bikes, and more: http://www.n0nb.us
______________________________________________________________
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

Bob Cunnings NW8L

Re: Is a K3 ATU with balanced outputs possible?

In reply to this post by Andrew Moore-3

Maybe not. The analysis presented in this article:

http://fermi.la.asu.edu/w9cf/articles/balun/

leads to the conclusion that locating the choke balun at the input of
the tuner, and floating the tuner, offers an advantage only for
balanced tuner designs (and good balance in the load). The stress on
the balun in a high SWR situation is unchanged by moving it to the
input. In short "An unbalanced tuner trades the large differential
mode impedance for a large unbalanced impedance making the balun's job
unchanged."

W8JI also addresses the issue in this article:

http://www.w8ji.com/tuner_baluns.htm

and comes to the same conclusion, with emphasis on the need for good
load balance in the case of a balanced tuner with choke balun at the
input. He ends with: "The irony is, moving the balun to the input
mostly works only when the balun is not needed!".

Food for thought.

I use a floating balanced-L tuner with choke balun at the input, but
try to keep decent balance in the antenna system for this reason.

Bob NW8L

>There may be no difference in efficiency between putting the balun at the input
>or the output of the tuner if you are operating into a nice 50ohm resistive
>dummy load, but the situation changes if you are operating into an antenna fed
>with ladder line on which there is a high SWR. In this case, the high SWR can
>cause high currents that saturate the ferrite core in the balun, and causing
>non-linearity and producing heat losses. This is why it may be preferable to
>locate the balun at the input of the tuner, where the SWR on the transmission
>line is low, and "float" the whole tuner. However, as Don mentioned, this can
>present difficulties if the tuner is not a balanced design.
>
>73, Matt VK2ACL

Eric Buggee; VK3AX

Re: Is a K3 ATU with balanced outputs possible?

In reply to this post by Don Wilhelm-4

Hi Don & all,
Yes the reason for the length of 285 Ft is based
on reading Cebick's musings in antennix on long wire anenna's / V beams
& on to Rhombic antenna's, where Cebick notes that odd multiples of 1/4
wavelength produce slightly more gain than multiples of 1/2 wavelength.

I think that I stumbled upon some serendipity with the 285Ft length
cause it sure works! All noted re the Bi-directionality, I considered
it not worth the aggrivation & trouble to terminate the wires thats for
sure.

73 from,

Eric Buggee, VK3AX.

On 9/29/2012 10:22 AM, Don Wilhelm wrote:

> Eric,
>
> A "V" beam will be quite directional (bidirectional) and the response
> depends on frequency. especially at those frequencies where the length
> is in excess of 1 wavelength.
>
> You must have found a good length if it operates well with the BL2 and
> the KAT3 combination.
> The wire angle of 70 degrees is good for 40 meters through 20 meters,
> but is effective for other bands as well.
>
> 73,
> Don W3FPR
>
> On 9/28/2012 8:04 PM, Eric Buggee wrote:
>> Hi Andrew, Don & all,
>>
>> I have a K3 (4520) and have recently installed a new antenna in the form
>> of a "V" beam with the bisector at about 7 Degrees east of North, with
>> the included angle at about 70 degrees and a leg length of 285Ft, height
>> above ground is 70 to 75 Ft, with ground sloping down away to N & NE for
>> 20Km.
>>
>> I have found that using the KAT3 in the K3 and a BL2 Balun it is useable
>> on all bands from 160 through to 6M with the worst VSWR of 1.5:1 showing
>> up on 160 at 1860KHz.
>>
>> Reports from stations at, 1 to 5000 Km north from Emerald in the ranges
>> 60 KM East of Melbourne in VK3 land give the "V" beam an advantage of 2
>> to 3 Sunits over the main antenna running NE to SW (A full sized 160M
>> dipole at 105Ft, fed with OW line spced 6inches) .
>>
>> Reports run as follows:- 160M, generally 1 S unit down WR to the 160M
>> dipole;
>>
>> 80M, equal to & sometimes 1 S unit better (on average) compared to the
>> 160 M dipole appears to be dependent upon time of day & prop'n
>> conditions;
>>
>> 40M, definitely better with 1 to 2 S units better most of the time (day
>> or night);
>>
>> 30 M, definitely better by consistent 2 to 3 Sunits better at 3 to
>> 5000Km;
>>
>> 20 M like 30 M consistently better than the 160 M dipole by 2 to 3 S
>> units at 3 to 5000Km distance.
>>
>> The higher bands, with the V Beam I am hearing DX stations that are not
>> even detectable on the 160 M dipole (8 & 24MHz), but, so far no
>> definitive contacts made using the V beam to give a real evalution as
>> yet. It has only been operational for about 10 days.
>>
>> Hope the foregoing is of interest,
>>
>> 73,
>>
>> From Eric VK3AX.
>>
>>
>>
>> On 9/29/2012 9:06 AM, Andrew Moore wrote:
>>> Great; thank you for the trivia, very helpful. I figured it had already
>>> been considered and that there was a good reason for the current
>>> configuration.
>>>
>>> The BL2 following the KAT3 was exactly one option I was considering.
>>> I've
>>> read about several cases in which ops had success, but read others
>>> in which
>>> the balun was heating perhaps due to excessive reactance on the antenna
>>> side. Reactance is likely dependent on the frequency/band and several
>>> factors in the antenna system which could explain the mixed results.
>>>
>>> I think I will try this approach and enjoy the experimenting.
>>>
>>> All: Not looking to turn this in to an OT antenna theory thread, but
>>> if you
>>> have specific experience with this configuration, I'd like to hear
>>> (KAT3 to
>>> BL2 to ladder to simple dipole).
>>>
>>> Thanks,
>>> --Andrew, NV1B
>>> maineware.net
>>> ..
>>>
>>>
>>> On Fri, Sep 28, 2012 at 6:43 PM, Don Wilhelm <[hidden email]>
>>> wrote:
>>>
>>>> Andrew,
>>>>
>>>> A bit of 'trivia' first:
>>>> That was "supposed" to be a solution in the KAT500 tuner. The initial
>>>> design put the balun on the input of the tuner, and attempted to
>>>> "float"
>>>> the rest of the tuner while trying to maintain balance.
>>>>
>>>> There were problems with maintaining balance through the rest of the
>>>> tuner, while studies indicated there was no efficiency difference
>>>> between
>>>> the balun at the input vs. the balun at the output, so the design was
>>>> changed to an unbalanced design driving (if required or desired) a
>>>> balun at
>>>> the output of the tuner.
>>>>
>>>> "trivia off":
>>>>
>>>> So more specific to your question, a balanced output from the K3
>>>> KAT3 can
>>>> easily be obtained by using an Elecraft BL2 on the output side of
>>>> the KAT3.
>>>>
>>>>
>>> ______________________________________________________________
>>> 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
>> 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
>>
>
>

Don Wilhelm-4

Re: Is a K3 ATU with balanced outputs possible?

In reply to this post by Bob Cunnings NW8L

Bob,

My analysis - while "floating the unbalanced tuner" may be possible in
theory, in practice, it is not practical. There are always be points
that will be found to upset the balance.

There is a reason for creating balanced networks, and putting the balun
on the input of an unbalanced network is just not one of them.

The bottom line is found at the end of the W8JI article. "Moving the
balun to the input is only helpful when the balun is not needed". So
use the KAT100 or KAT500 as designed and put a balun on the output if
you must use balanced feed.

73,
Don W3FPR

On 9/28/2012 9:47 PM, Bob Cunnings wrote:

> Maybe not. The analysis presented in this article:
>
> http://fermi.la.asu.edu/w9cf/articles/balun/
>
> leads to the conclusion that locating the choke balun at the input of
> the tuner, and floating the tuner, offers an advantage only for
> balanced tuner designs (and good balance in the load). The stress on
> the balun in a high SWR situation is unchanged by moving it to the
> input. In short "An unbalanced tuner trades the large differential
> mode impedance for a large unbalanced impedance making the balun's job
> unchanged."
>
> W8JI also addresses the issue in this article:
>
> http://www.w8ji.com/tuner_baluns.htm
>
> and comes to the same conclusion, with emphasis on the need for good
> load balance in the case of a balanced tuner with choke balun at the
> input. He ends with: "The irony is, moving the balun to the input
> mostly works only when the balun is not needed!".
>
> Food for thought.
>
> I use a floating balanced-L tuner with choke balun at the input, but
> try to keep decent balance in the antenna system for this reason.
>
> Bob NW8L
>
>> There may be no difference in efficiency between putting the balun at the input
>> or the output of the tuner if you are operating into a nice 50ohm resistive
>> dummy load, but the situation changes if you are operating into an antenna fed
>> with ladder line on which there is a high SWR. In this case, the high SWR can
>> cause high currents that saturate the ferrite core in the balun, and causing
>> non-linearity and producing heat losses. This is why it may be preferable to
>> locate the balun at the input of the tuner, where the SWR on the transmission
>> line is low, and "float" the whole tuner. However, as Don mentioned, this can
>> present difficulties if the tuner is not a balanced design.
>>
>> 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
>

N5GE-2

Re: Is a K3 ATU with balanced outputs possible?

In reply to this post by Andrew Moore-3

Put the balun outside and bring the coax into the shack.

I am feeding a large NVIS loop with my K3. The loop is fed with 450
ohm window line which connects to a 4:1 balun under the eve of the
roof before it enters the shack. The K3 is connected to the balun
with 50 ohm coax. My K3 tuner will match the load from 160 to 10
meters. When running the KPA500 I use a large 2000W tuner.

Aword of caution: Make sure your window/ladder line does not touch
the house anywhere. It could start a fire.

Amateur Radio Operator N5GE
ARRL Lifetime Member
QCWA Lifetime Member

On Fri, 28 Sep 2012 19:06:36 -0400, Andrew Moore
<[hidden email]> wrote:

>Great; thank you for the trivia, very helpful. I figured it had already
>been considered and that there was a good reason for the current
>configuration.
>
>The BL2 following the KAT3 was exactly one option I was considering. I've
>read about several cases in which ops had success, but read others in which
>the balun was heating perhaps due to excessive reactance on the antenna
>side. Reactance is likely dependent on the frequency/band and several
>factors in the antenna system which could explain the mixed results.
>
>I think I will try this approach and enjoy the experimenting.
>
>All: Not looking to turn this in to an OT antenna theory thread, but if you
>have specific experience with this configuration, I'd like to hear (KAT3 to
>BL2 to ladder to simple dipole).
>
>Thanks,
>--Andrew, NV1B
>maineware.net
>..
>
>
>On Fri, Sep 28, 2012 at 6:43 PM, Don Wilhelm <[hidden email]> wrote:
>
>> Andrew,
>>
>> A bit of 'trivia' first:
>> That was "supposed" to be a solution in the KAT500 tuner. The initial
>> design put the balun on the input of the tuner, and attempted to "float"
>> the rest of the tuner while trying to maintain balance.
>>
>> There were problems with maintaining balance through the rest of the
>> tuner, while studies indicated there was no efficiency difference between
>> the balun at the input vs. the balun at the output, so the design was
>> changed to an unbalanced design driving (if required or desired) a balun at
>> the output of the tuner.
>>
>> "trivia off":
>>
>> So more specific to your question, a balanced output from the K3 KAT3 can
>> easily be obtained by using an Elecraft BL2 on the output side of the KAT3.
>>
>>
>______________________________________________________________
>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