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alsopb

High power tuner

[hidden email]

An example of how the price of a tuner can grow astronomically with
power level.
At what point does it make more sense to spend the same $$ for antennas
which don't require a tuner?

73 de Brian/K3KO
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Van W1WCG

Re: High power tuner

No-tune antennas such as the B&W all-band no-tune folded dipole
generally waste half the power
fed them in the termination resistor. However, you can get a good
all-band high-power
memory tuner for much, much less than what I would imagine that Alpha
tuner will cost,
and feed an all-band antenna like a G5RV with good results.

Van W1WCG

> [hidden email]
>
> An example of how the price of a tuner can grow astronomically with
> power level.
> At what point does it make more sense to spend the same $$ for antennas
> which don't require a tuner?
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P.B. Christensen

Re: High power tuner

In reply to this post by alsopb

> An example of how the price of a tuner can grow astronomically with
> power level.
> At what point does it make more sense to spend the same $$ for antennas
> which don't require a tuner?

For some of us where only one HF antenna is feasible, it may make sense to
put all the money in the tuner and *not* the antenna. For example, I've
gotten away with an 80m dipole at 60-ft in my gated community, only due to
the natural antenna supports: pine trees. For me, the optimal solution for
80m-10m coverage, consists of a remote-controlled, symmetrical tuner built
in a WX-proof enclosure and located at the base of an open feeder line.
This offers me minimum system loss, minimum RFI leakage to my transmission
line, and all band coverage. Sure, I have no control over maximum lobes and
minimum nulls at higher frequencies, but given the QTH constrains, it made
sense to put all the money into a truly balanced tuner and nearly zero cost
in the antenna. Through 4Nec2 modeling and TLD, my antenna system losses
are very low and in all cases, exceeds the performance of resonant mono-band
dipoles fed with LMR-400. My 600-ohm line length is optimized for all bands
using an N2PK VNA.

The new RF Concepts tuner would not work well for me. It's an unbalanced
C-L-C design with a CM choke input, similar in design with several Palstar
tuners, only with much more rugged components than what Palstar provides.
W9CF, W7EL, and W8JI have analyzed a current choke placed at the input to a
C-L-C tuner and have concluded that placement at the input is not as
effective for maintaining line balance as a balun placed at the tuner's
output. The exception being if the CM choke is placed at the input of a
symmetrical, balanced tuner (e.g., AG6K type). My tuner is of this type and
can be seen on my QRZ.com page.

Read through the eHam reviews and see just how gullible we are when it comes
to tuner evaluation. Nearly all accolades are based on: (1) the ability of
the tuner to achieve an input VSWR of 1:1; (2) pretty layout; and (3)
component size. None of these factors tell us about the tuner's efficiency.
When a tuner needs it own cooling and ventilation system to function, that
should throw up red warning flags.

The new RF Concepts tuner has switched, 8pF to 800 pF output C. Although
better than most commercial tuners, it would have been even better to at
least double that amount so long as minimum C is maintained through high
isolation switched C. The real *big* unknown with the new tuner is coil Q
over its entire range. I would like to see a Q plot of the coil mounted in
the metal enclosure. That's a critical piece of evidence in order to
evaluate the tuner's efficiency, especially with low-Z line terminations.
With both input and out C being vacuum types, I would expect high-Q for the
C components. I'm not too concerned about a tuner's ability to tune and
match low-Z loads. For base station operation, there are few combinations
of full size wire antennas that place a low-Z at the line input, no matter
the line length. If I'm dealing with low-Z transmission line inputs, then
its an antenna I probably don't want in the first place. For portable and
mobile installations, that a wholly different matter.

Finally, the new RF Concepts tuner has a slick Smith chart display on the
front panel. Only, the charting shows the Z at the input of the tuner which
is of very limited value. Since the input is always tuned and matched for
50+j0, even the simple Monimatch circuit is sufficient for that purpose.
So, it's nice "eye candy" but I see nearly no value in the display.

Paul, W9AC

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Joe Subich, W4TV-4

Re: High power tuner

> The new RF Concepts tuner would not work well for me. It's an
> unbalanced C-L-C design with a CM choke input, similar in design
> with several Palstar tuners, only with much more rugged components
> than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a
> current choke placed at the input to a C-L-C tuner and have concluded
> that placement at the input is not as effective for maintaining line
> balance as a balun placed at the tuner's output.

The common mode choke in the Alpha tuner will be completely ineffective
with any of the coaxial fed antenna outputs in any case! Since it is
*inside* a metal box and the input as well as output connectors are all
connected to the case, any common mode current will simply bypass the
the choke on the case!

The *only way* to make a common mode choke effective with an unbalanced
tuner is to connect the case of the tuner to a low impedance "ground"
and place the choke in the feedline between the rig/amplifier and the
tuner - external to the tuner.

73,

... Joe, W4TV

On 11/26/2011 11:04 AM, Paul Christensen wrote:

>> An example of how the price of a tuner can grow astronomically with
>> power level.
>> At what point does it make more sense to spend the same $$ for antennas
>> which don't require a tuner?
>
> For some of us where only one HF antenna is feasible, it may make sense to
> put all the money in the tuner and *not* the antenna. For example, I've
> gotten away with an 80m dipole at 60-ft in my gated community, only due to
> the natural antenna supports: pine trees. For me, the optimal solution for
> 80m-10m coverage, consists of a remote-controlled, symmetrical tuner built
> in a WX-proof enclosure and located at the base of an open feeder line.
> This offers me minimum system loss, minimum RFI leakage to my transmission
> line, and all band coverage. Sure, I have no control over maximum lobes and
> minimum nulls at higher frequencies, but given the QTH constrains, it made
> sense to put all the money into a truly balanced tuner and nearly zero cost
> in the antenna. Through 4Nec2 modeling and TLD, my antenna system losses
> are very low and in all cases, exceeds the performance of resonant mono-band
> dipoles fed with LMR-400. My 600-ohm line length is optimized for all bands
> using an N2PK VNA.
>
> The new RF Concepts tuner would not work well for me. It's an unbalanced
> C-L-C design with a CM choke input, similar in design with several Palstar
> tuners, only with much more rugged components than what Palstar provides.
> W9CF, W7EL, and W8JI have analyzed a current choke placed at the input to a
> C-L-C tuner and have concluded that placement at the input is not as
> effective for maintaining line balance as a balun placed at the tuner's
> output. The exception being if the CM choke is placed at the input of a
> symmetrical, balanced tuner (e.g., AG6K type). My tuner is of this type and
> can be seen on my QRZ.com page.
>
> Read through the eHam reviews and see just how gullible we are when it comes
> to tuner evaluation. Nearly all accolades are based on: (1) the ability of
> the tuner to achieve an input VSWR of 1:1; (2) pretty layout; and (3)
> component size. None of these factors tell us about the tuner's efficiency.
> When a tuner needs it own cooling and ventilation system to function, that
> should throw up red warning flags.
>
> The new RF Concepts tuner has switched, 8pF to 800 pF output C. Although
> better than most commercial tuners, it would have been even better to at
> least double that amount so long as minimum C is maintained through high
> isolation switched C. The real *big* unknown with the new tuner is coil Q
> over its entire range. I would like to see a Q plot of the coil mounted in
> the metal enclosure. That's a critical piece of evidence in order to
> evaluate the tuner's efficiency, especially with low-Z line terminations.
> With both input and out C being vacuum types, I would expect high-Q for the
> C components. I'm not too concerned about a tuner's ability to tune and
> match low-Z loads. For base station operation, there are few combinations
> of full size wire antennas that place a low-Z at the line input, no matter
> the line length. If I'm dealing with low-Z transmission line inputs, then
> its an antenna I probably don't want in the first place. For portable and
> mobile installations, that a wholly different matter.
>
> Finally, the new RF Concepts tuner has a slick Smith chart display on the
> front panel. Only, the charting shows the Z at the input of the tuner which
> is of very limited value. Since the input is always tuned and matched for
> 50+j0, even the simple Monimatch circuit is sufficient for that purpose.
> So, it's nice "eye candy" but I see nearly no value in the display.
>
> Paul, W9AC
>
>
>
> ______________________________________________________________
> 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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P.B. Christensen

Re: High power tuner

In reply to this post by P.B. Christensen

Looking at the RF Concepts simplified schematic diagram, the directional
coupler appears to remain active when the tuner is in "bypass." So, as long
as the Smith chart feature works in bypass, it would definitely provide some
useful information about the line input Z within the limits of the
directional coupler accuracy.

Paul, W9AC

----- Original Message -----
From: "Paul Christensen" <[hidden email]>
To: <[hidden email]>
Sent: Saturday, November 26, 2011 11:04 AM
Subject: Re: [Elecraft] High power tuner

>> An example of how the price of a tuner can grow astronomically with
>> power level.
>> At what point does it make more sense to spend the same $$ for antennas
>> which don't require a tuner?
>
> For some of us where only one HF antenna is feasible, it may make sense to
> put all the money in the tuner and *not* the antenna. For example, I've
> gotten away with an 80m dipole at 60-ft in my gated community, only due to
> the natural antenna supports: pine trees. For me, the optimal solution
> for
> 80m-10m coverage, consists of a remote-controlled, symmetrical tuner built
> in a WX-proof enclosure and located at the base of an open feeder line.
> This offers me minimum system loss, minimum RFI leakage to my transmission
> line, and all band coverage. Sure, I have no control over maximum lobes
> and
> minimum nulls at higher frequencies, but given the QTH constrains, it made
> sense to put all the money into a truly balanced tuner and nearly zero
> cost
> in the antenna. Through 4Nec2 modeling and TLD, my antenna system losses
> are very low and in all cases, exceeds the performance of resonant
> mono-band
> dipoles fed with LMR-400. My 600-ohm line length is optimized for all
> bands
> using an N2PK VNA.
>
> The new RF Concepts tuner would not work well for me. It's an unbalanced
> C-L-C design with a CM choke input, similar in design with several Palstar
> tuners, only with much more rugged components than what Palstar provides.
> W9CF, W7EL, and W8JI have analyzed a current choke placed at the input to
> a
> C-L-C tuner and have concluded that placement at the input is not as
> effective for maintaining line balance as a balun placed at the tuner's
> output. The exception being if the CM choke is placed at the input of a
> symmetrical, balanced tuner (e.g., AG6K type). My tuner is of this type
> and
> can be seen on my QRZ.com page.
>
> Read through the eHam reviews and see just how gullible we are when it
> comes
> to tuner evaluation. Nearly all accolades are based on: (1) the ability
> of
> the tuner to achieve an input VSWR of 1:1; (2) pretty layout; and (3)
> component size. None of these factors tell us about the tuner's
> efficiency.
> When a tuner needs it own cooling and ventilation system to function, that
> should throw up red warning flags.
>
> The new RF Concepts tuner has switched, 8pF to 800 pF output C. Although
> better than most commercial tuners, it would have been even better to at
> least double that amount so long as minimum C is maintained through high
> isolation switched C. The real *big* unknown with the new tuner is coil Q
> over its entire range. I would like to see a Q plot of the coil mounted
> in
> the metal enclosure. That's a critical piece of evidence in order to
> evaluate the tuner's efficiency, especially with low-Z line terminations.
> With both input and out C being vacuum types, I would expect high-Q for
> the
> C components. I'm not too concerned about a tuner's ability to tune and
> match low-Z loads. For base station operation, there are few combinations
> of full size wire antennas that place a low-Z at the line input, no matter
> the line length. If I'm dealing with low-Z transmission line inputs, then
> its an antenna I probably don't want in the first place. For portable and
> mobile installations, that a wholly different matter.
>
> Finally, the new RF Concepts tuner has a slick Smith chart display on the
> front panel. Only, the charting shows the Z at the input of the tuner
> which
> is of very limited value. Since the input is always tuned and matched for
> 50+j0, even the simple Monimatch circuit is sufficient for that purpose.
> So, it's nice "eye candy" but I see nearly no value in the display.
>
> Paul, W9AC
>
>
>
> ______________________________________________________________
> 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

Vic Rosenthal

Re: High power tuner

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

The balanced output is not referenced to the case. So the balun is functional when feeding
a balanced line, not shorted as you suggest. However, you are correct that it will not
serve as a common mode choke with unbalanced output. And Paul's comments about the
placement of the balun are correct. I was surprised to see this from Alpha, whom I would
have expected to know better.

I suppose I'll have to wait for the KAT1500 (no, no such product has been announced or
hinted at as far as I know!)

On 11/26/2011 8:55 AM, Joe Subich, W4TV wrote:

>
>> The new RF Concepts tuner would not work well for me. It's an
>> unbalanced C-L-C design with a CM choke input, similar in design
>> with several Palstar tuners, only with much more rugged components
>> than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a
>> current choke placed at the input to a C-L-C tuner and have concluded
>> that placement at the input is not as effective for maintaining line
>> balance as a balun placed at the tuner's output.
> The common mode choke in the Alpha tuner will be completely ineffective
> with any of the coaxial fed antenna outputs in any case! Since it is
> *inside* a metal box and the input as well as output connectors are all
> connected to the case, any common mode current will simply bypass the
> the choke on the case!
>
> The *only way* to make a common mode choke effective with an unbalanced
> tuner is to connect the case of the tuner to a low impedance "ground"
> and place the choke in the feedline between the rig/amplifier and the
> tuner - external to the tuner.
>
> 73,
>
> ... Joe, W4TV
>
>

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/

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Gary Gregory

Re: High power tuner

Vic,

I'm waiting for a KPA-1500 with the inbuilt auto-tuner.....oops, gotta run, the nice young man in the white coat is calling me again....

Gary

VK4FD - Motorhome Mobile
Elecraft Equipment
K3 #679, KPA-500 #018
Living the dream!!!

----- Original Message -----
From: Vic K2VCO
To: [hidden email]
Sent: Sunday, November 27, 2011 9:00 AM
Subject: Re: [Elecraft] High power tuner

The balanced output is not referenced to the case. So the balun is functional when feeding
a balanced line, not shorted as you suggest. However, you are correct that it will not
serve as a common mode choke with unbalanced output. And Paul's comments about the
placement of the balun are correct. I was surprised to see this from Alpha, whom I would
have expected to know better.

I suppose I'll have to wait for the KAT1500 (no, no such product has been announced or
hinted at as far as I know!)

On 11/26/2011 8:55 AM, Joe Subich, W4TV wrote:
>
>> The new RF Concepts tuner would not work well for me. It's an
>> unbalanced C-L-C design with a CM choke input, similar in design
>> with several Palstar tuners, only with much more rugged components
>> than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a
>> current choke placed at the input to a C-L-C tuner and have concluded
>> that placement at the input is not as effective for maintaining line
>> balance as a balun placed at the tuner's output.
> The common mode choke in the Alpha tuner will be completely ineffective
> with any of the coaxial fed antenna outputs in any case! Since it is
> *inside* a metal box and the input as well as output connectors are all
> connected to the case, any common mode current will simply bypass the
> the choke on the case!
>
> The *only way* to make a common mode choke effective with an unbalanced
> tuner is to connect the case of the tuner to a low impedance "ground"
> and place the choke in the feedline between the rig/amplifier and the
> tuner - external to the tuner.
>
> 73,
>
> ... Joe, W4TV
>
>

--
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/

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Joe Subich, W4TV-4

Re: High power tuner

In reply to this post by Vic Rosenthal

On 11/26/2011 6:00 PM, Vic K2VCO wrote:
> The balanced output is not referenced to the case. So the balun is
> functional when feeding a balanced line, not shorted as you suggest.

You are correct, that the balun is not shorted when feeding a balanced
antenna. However, in that configuration it will *only* function as a
common mode choke (if it is not constructed as a voltage balun).

Any antenna connected to the "balanced" terminals will still not be
truly "balanced" as it is not possible to generate a balanced output
at the output of an unbalanced network by forcing balance at the input
of that network. It is quite likely that a "balun" at the input of
an unbalanced network will only increase circulating currents (and
losses) in the network.

73,

... Joe, W4TV

On 11/26/2011 6:00 PM, Vic K2VCO wrote:

> The balanced output is not referenced to the case. So the balun is functional when feeding
> a balanced line, not shorted as you suggest. However, you are correct that it will not
> serve as a common mode choke with unbalanced output. And Paul's comments about the
> placement of the balun are correct. I was surprised to see this from Alpha, whom I would
> have expected to know better.
>
> I suppose I'll have to wait for the KAT1500 (no, no such product has been announced or
> hinted at as far as I know!)
>
> On 11/26/2011 8:55 AM, Joe Subich, W4TV wrote:
>>
>>> The new RF Concepts tuner would not work well for me. It's an
>>> unbalanced C-L-C design with a CM choke input, similar in design
>>> with several Palstar tuners, only with much more rugged components
>>> than what Palstar provides. W9CF, W7EL, and W8JI have analyzed a
>>> current choke placed at the input to a C-L-C tuner and have concluded
>>> that placement at the input is not as effective for maintaining line
>>> balance as a balun placed at the tuner's output.
>> The common mode choke in the Alpha tuner will be completely ineffective
>> with any of the coaxial fed antenna outputs in any case! Since it is
>> *inside* a metal box and the input as well as output connectors are all
>> connected to the case, any common mode current will simply bypass the
>> the choke on the case!
>>
>> The *only way* to make a common mode choke effective with an unbalanced
>> tuner is to connect the case of the tuner to a low impedance "ground"
>> and place the choke in the feedline between the rig/amplifier and the
>> tuner - external to the tuner.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>

P.B. Christensen

Re: High power tuner

In reply to this post by Vic Rosenthal

> I was surprised to see this from Alpha, whom I would have expected to know
> better.

The identical design (less automated functions) can seen in recent issues of
the ARRL Antenna Book For example, see 20th Ed., pp. 25/15 - 25/19 and
titled "High-Power ARRL Antenna Tuner for Balanced or Unbalanced Lines."
Even output C is the same at 800 pF max.

Paul, W9AC

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Vic Rosenthal

Re: High power tuner

I know. I expected better of them, too.

On 11/26/2011 5:37 PM, Paul Christensen wrote:

>> I was surprised to see this from Alpha, whom I would have expected to know
>> better.
> The identical design (less automated functions) can seen in recent issues of
> the ARRL Antenna Book For example, see 20th Ed., pp. 25/15 - 25/19 and
> titled "High-Power ARRL Antenna Tuner for Balanced or Unbalanced Lines."
> Even output C is the same at 800 pF max.
>
> Paul, W9AC
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html

Jim AB3CV

Re: High power tuner

Google W9CF for an explanation of why a choke balun works and why is
matters not if it's on the input or output of a tuner except for convience.
Also provides math showing needed CM choke impedence.

Google K9YC for a set of measurements of real life CM chokes and
suggestions for full legal limit recipes that meet the needed impedences.

jim ab3cv
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P.B. Christensen

Re: High power tuner

> Google W9CF for an explanation of why a choke balun works and why is
> matters not if it's on the input or output of a tuner except for
> convience.

What W9CF said was this:

"As noted by Roy Lewallen, W7EL,[2] putting a choke balun on the input of an
unbalanced tuner to drive a balanced line is useless. It introduces a
``hot'' tuner case which must be isolated with no benefit over putting the
balun on the output."

Introducing a hot chassis full of CM current isn't trivial.

Paul, W9AC

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Don Wilhelm-4

Re: High power tuner

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

A balanced version of the "T" network is a physical monstrosity
requiring that both ends of the capacitors float, but is possible. The
T network has the greatest matching range, but suffers from false
matches resulting on high circulating currents in the tuner.

A balanced "L" network should not be difficult to produce, but if I may,
I would like to put in a plug for my favorite balanced tuner which is
IMHO is the old fashoined parallel (or series) resonant tank circuit
using a link coupler. No balun required, but it does not lend itself
easily to band switching. As a single band tuner, it is the ultimate
IMHO, and the venerable Johnson Matchbox was an attempt to make that
basic circuit bandswitchable. The Matchbox has some limitations in the
matching range it can handle. My Johnson Matchbox will only be pried
from my hands over my "cold dead body" - I do not use it much, but it
really is handy for creating artificial antennas with SWR in the
workshop, and it works quite well as a bandpass filter when that is needed.

73,
Don W3FPR

On 11/26/2011 6:48 PM, Joe Subich, W4TV wrote:

> On 11/26/2011 6:00 PM, Vic K2VCO wrote:
>> The balanced output is not referenced to the case. So the balun is
>> functional when feeding a balanced line, not shorted as you suggest.
> You are correct, that the balun is not shorted when feeding a balanced
> antenna. However, in that configuration it will *only* function as a
> common mode choke (if it is not constructed as a voltage balun).
>
> Any antenna connected to the "balanced" terminals will still not be
> truly "balanced" as it is not possible to generate a balanced output
> at the output of an unbalanced network by forcing balance at the input
> of that network. It is quite likely that a "balun" at the input of
> an unbalanced network will only increase circulating currents (and
> losses) in the network.
>
> 73,
>
> ... Joe, W4TV
>
>

David Gilbert

Re: High power tuner

In reply to this post by P.B. Christensen

If I remember correctly, the announcement for the Alpha tuner even
stated that they "drew heavily" (or words to that effect) from the ARRL
Antenna Book for the design.

73,
Dave AB7E

On 11/26/2011 6:37 PM, Paul Christensen wrote:

Don Wilhelm-4

Re: High power tuner

Just because it was published by the ARRL does not make it a good
design, although it might help to sell a few.

Zack Lau published a QRP version of that tuner some years back and later
retracted it, and it has not been mentioned much since, but Dean Straw
published his high power version of about the same design and that seems
to be the "best thing since sliced bread" despite counterclaims by noted
authorities on balun and RF designs - W8JI, W7El and others. Bottom
line, it just does not work well, although there will be many who will
say that "Alpha makes good stuff", that still makes it a stretch of the
laws of physics - using an unbalanced network "floating" (although not
really isolated from a common reference (ground)) will still not make
everything balanced.

I know there are those who will claim that an off center fed dipole has
a balanced feedpoint, but I am not convinced. I put the "balun at the
input" tuners in the same category. Take a balanced signal (output of a
balun) and feed it through an unbalanced network, and claim that the
output of that unbalanced network is balanced just does not make much
sense to me. Maybe with ideal components it *might* be possible, but if
one would plot the reactance and phase delay around that unbalanced
network using good scientific methods, it would become obvious that the
output would not be of equal and opposite currents with 180 degrees
phase difference. If the schematic does not look balanced, it is not
really balanced. Follow the leading current and lagging current around
the circuit to convince yourself.

73,
Don W3FPR

On 11/26/2011 10:10 PM, David Gilbert wrote:

> If I remember correctly, the announcement for the Alpha tuner even
> stated that they "drew heavily" (or words to that effect) from the ARRL
> Antenna Book for the design.
>
> 73,
> Dave AB7E
>
>
>
> On 11/26/2011 6:37 PM, Paul Christensen wrote:
>>> I was surprised to see this from Alpha, whom I would have expected to know
>>> better.
>> The identical design (less automated functions) can seen in recent issues of
>> the ARRL Antenna Book For example, see 20th Ed., pp. 25/15 - 25/19 and
>> titled "High-Power ARRL Antenna Tuner for Balanced or Unbalanced Lines."
>> Even output C is the same at 800 pF max.
>>
>> Paul, W9AC
>>
>> __
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>
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David Gilbert

Re: High power tuner

You misunderstand me. I never said that being published by the ARRL
made it a good design, and in fact I think that the ARRL has a horrible
track record for technical integrity on many of their published articles
(particularly those in QST). Much of what we read there is just flat
out wrong. I merely pointed out that Alpha seemed to think that being
published in ARRL gave the tuner design credibility ... an unwarranted
association from my perspective.

Dave AB7E

On 11/26/2011 8:44 PM, Don Wilhelm wrote:

> Just because it was published by the ARRL does not make it a good
> design, although it might help to sell a few.
>
> Zack Lau published a QRP version of that tuner some years back and later
> retracted it, and it has not been mentioned much since, but Dean Straw
> published his high power version of about the same design and that seems
> to be the "best thing since sliced bread" despite counterclaims by noted
> authorities on balun and RF designs - W8JI, W7El and others. Bottom
> line, it just does not work well, although there will be many who will
> say that "Alpha makes good stuff", that still makes it a stretch of the
> laws of physics - using an unbalanced network "floating" (although not
> really isolated from a common reference (ground)) will still not make
> everything balanced.
>
> I know there are those who will claim that an off center fed dipole has
> a balanced feedpoint, but I am not convinced. I put the "balun at the
> input" tuners in the same category. Take a balanced signal (output of a
> balun) and feed it through an unbalanced network, and claim that the
> output of that unbalanced network is balanced just does not make much
> sense to me. Maybe with ideal components it *might* be possible, but if
> one would plot the reactance and phase delay around that unbalanced
> network using good scientific methods, it would become obvious that the
> output would not be of equal and opposite currents with 180 degrees
> phase difference. If the schematic does not look balanced, it is not
> really balanced. Follow the leading current and lagging current around
> the circuit to convince yourself.
>
> 73,
> Don W3FPR
>
> On 11/26/2011 10:10 PM, David Gilbert wrote:
>> If I remember correctly, the announcement for the Alpha tuner even
>> stated that they "drew heavily" (or words to that effect) from the ARRL
>> Antenna Book for the design.
>>
>> 73,
>> Dave AB7E
>>
>>
>>
>> On 11/26/2011 6:37 PM, Paul Christensen wrote:
>>>> I was surprised to see this from Alpha, whom I would have expected to know
>>>> better.
>>> The identical design (less automated functions) can seen in recent issues of
>>> the ARRL Antenna Book For example, see 20th Ed., pp. 25/15 - 25/19 and
>>> titled "High-Power ARRL Antenna Tuner for Balanced or Unbalanced Lines."
>>> Even output C is the same at 800 pF max.
>>>
>>> Paul, W9AC
>>>
>>> __
>> ______________________________________________________________
>> 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
>