LDG Z11 Pro II tuner with an Icom IC-761
 

Recently acquired an LDG tuner. Nice part.
I'm looking forward to the not having to twist knobs every
time I change frequency.
It comes with an adapter cable for Icom radios, but it's a
4-pin Molex connector and the manual doesn't show what the
connections/signals are for the radio.
Anyone out there connect this tuner to an IC-761 already?

Thanks
Jeff-1.0
wa6fwi

--
"Everything from Crackers to Coffins"

LDG Z11 Pro II tuner with an Icom IC-761
 

On Wed, 28 Sep 2011 10:46:44 -0500, Jeffrey Angus
wrote:

Recently acquired an LDG tuner. Nice part.
I'm looking forward to the not having to twist knobs every
time I change frequency.

Ok, you're lazy.

It comes with an adapter cable for Icom radios, but it's a
4-pin Molex connector and the manual doesn't show what the
connections/signals are for the radio.
Anyone out there connect this tuner to an IC-761 already?

Buy or clone the LDG Icom interface cable. The IC-761 supports the
Icom AH-4 antenna tuna, so it should work:
http://www.ldgelectronics.com/c/252/products/13/23/1
The warrany on this advice expires after you read this message.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

LDG Z11 Pro II tuner with an Icom IC-761
 

On Wed, 28 Sep 2011 09:26:36 -0700, Jeff Liebermann
wrote:

On Wed, 28 Sep 2011 10:46:44 -0500, Jeffrey Angus
wrote:

Recently acquired an LDG tuner. Nice part.
I'm looking forward to the not having to twist knobs every
time I change frequency.

Ok, you're lazy.

It comes with an adapter cable for Icom radios, but it's a
4-pin Molex connector and the manual doesn't show what the
connections/signals are for the radio.
Anyone out there connect this tuner to an IC-761 already?

Buy or clone the LDG Icom interface cable. The IC-761 supports the
Icom AH-4 antenna tuna, so it should work:
http://www.ldgelectronics.com/c/252/products/13/23/1
The warrany on this advice expires after you read this message.

Schematic:
http://www.ldgelectronics.com/assets/images/products/cables/IC%20cable.jpg
Alternate source:
http://www.cheapham.com/products/LDG-IC%252dPAC%252d6-Icom-Interface-Cable-%252d-6-Foot.html

Hmmm... why do you need an antenna tuner? Can't you build an antenna
that's close to 50 ohms? Or, are you like me and just hang any random
length of wire in the trees and hope for the best?

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

LDG Z11 Pro II tuner with an Icom IC-761
 

On 9/28/2011 11:37 AM, Jeff Liebermann wrote:
Hmmm... why do you need an antenna tuner? Can't you build an antenna
that's close to 50 ohms? Or, are you like me and just hang any random
length of wire in the trees and hope for the best?

For close to 40 years I bought into the myth of 50 ohm antennas.
Absolute crap results. (Well, I've always had very good luck with
a dipole for one band.)

Earlier this year I put up a 102' doublet fed with open wire line
and have been working the entire planet with less than 100 watts.

But you're right, I'm a lazy ******* and would like the frequency
agility rather than having to tweak the knobs on the MFJ tuner
every time I change frequency.

Jeff-1.0
wa6fwi

--
"Everything from Crackers to Coffins"

LDG Z11 Pro II tuner with an Icom IC-761
 

On Wed, 28 Sep 2011 15:46:35 -0500, Jeffrey Angus
wrote:

On 9/28/2011 11:37 AM, Jeff Liebermann wrote:
Hmmm... why do you need an antenna tuner? Can't you build an antenna
that's close to 50 ohms? Or, are you like me and just hang any random
length of wire in the trees and hope for the best?

For close to 40 years I bought into the myth of 50 ohm antennas.
Absolute crap results. (Well, I've always had very good luck with
a dipole for one band.)

Mythology went out with the Greeks and the Romans. Modern antenna
design requires newer beliefs and religions. Apparently, your
practices within the Cult of 50 ohms has failed to bring about the
desired miraculous DX. You might want to petition the radio gods for
a review of your design before you discard the cult completely.
However, there are alternative religions.

In my case, I switched and am now a practicing member of the Cult of
75 ohms. The difference is subtle. While worship of the 50 ohm idol
results in the maximum power transfer, the change to 75 ohms results
in minimum coax loss and somewhat easier antenna design. However, the
major benefit is it allows one to minimize the tithe paid to vendors
as CATV coax is cheap and readily available. I suggest you consider a
religious conversion.

Earlier this year I put up a 102' doublet fed with open wire line
and have been working the entire planet with less than 100 watts.

Hmmm... perhaps that's because the bands were miserable all last year
and have only recently begun to show signs of life. Timing is
everything.

I thought you were trying to load a barbed wire fence. I'm
dissapointed.

But you're right,

Far right, please.

I'm a lazy ******* and would like the frequency
agility rather than having to tweak the knobs on the MFJ tuner
every time I change frequency.

Yeah, I know the problem. Every time the kite at the end of your
102ft doublet looses altitude, and the middle scrapes ground, you have
to retune. However, the IC-761 has plenty of knobs and switches to
play with. I don't see how a few more on the tuner could make any
difference.

Jeff-1.0
wa6fwi

Why is my mouse glued to the mouse pad? Sigh.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831-336-2558
# http://802.11junk.com
# http://www.LearnByDestroying.com AE6KS

LDG Z11 Pro II tuner with an Icom IC-761
 

Jeffrey Angus wrote in news:j5vfh4$uh1$1@dont-
email.me:

Recently acquired an LDG tuner. Nice part.
I'm looking forward to the not having to twist knobs every
time I change frequency.
It comes with an adapter cable for Icom radios, but it's a
4-pin Molex connector and the manual doesn't show what the
connections/signals are for the radio.

I think your question relates to the connections between the LDG and that
Molex plug.

Was it LDG who supplied the adapter? If so, ask them. Seems a bit silly
that would supply the thing without adequate information on how to use it.

Owen

LDG Z11 Pro II tuner with an Icom IC-761
 

On 9/28/2011 7:00 PM, Owen Duffy wrote:
I think your question relates to the connections between the LDG and that
Molex plug.

Was it LDG who supplied the adapter? If so, ask them. Seems a bit silly
that would supply the thing without adequate information on how to use it.

Owen

Well, I did ask LDG and they were kind enough to send me the application
note describing the connections.

And the more I looked into this the more I realized, "You have an
antenna tuner built in into the Icom IC-761."

Homer Simpson moment, "Do-oh!"

However, the specified tuning range of the internal tuner is 16.7
to 150 ohms. The LDG is specified as 6 to 1000 ohms. A bit more
latitude.

OK, "How did I get side tracked like this?"

Earlier this year I got an MFJ Versa Tuner to use with the doublet
antenna. It works fine. But of course, it's manual. (But it does
have a 4:1 balun inside.) So I get the LDG in a swap for some
goodies. No balun inside. Ok, I ordered an MFJ 4:1 current balun.
And those do work a LOT smoother tuning that with the internal
4:1 voltage type the MFJ tuner has.

It was while obsessing over the "talk to the radio" cable for the
LDG that I realized, "Oh right, this is designed for radios that
don't have internal tuners." For example, my Icom IC-726 has the
correct interface to talk to the LDG. I do have the matching AT-150
auto-tuner for the IC-726. That is specified the same as the IC-761
tuner.

Once the balun gets here, the FIRST thing I'm going to do is to
find out if the internal tuner has enough range to deal with my
antenna.

I just love wild goose chases, because in the end, you usually do
learn something useful in the process.

Jeff-1.0
wa6fwi



--
"Everything from Crackers to Coffins"

LDG Z11 Pro II tuner with an Icom IC-761
 

On 9/28/2011 6:03 PM, Jeff Liebermann wrote:
Mythology went out with the Greeks and the Romans. Modern antenna
design requires newer beliefs and religions. Apparently, your
practices within the Cult of 50 ohms has failed to bring about the
desired miraculous DX. You might want to petition the radio gods for
a review of your design before you discard the cult completely.
However, there are alternative religions.

Well, I've come to a few conclusions.
1. Dipoles with a 1:1 balun work very well.
2. See #1. However, the trees and other things they are attached to
are hard to rotate.
3. Vertical antennas load nicely. So do Bird Termalines. And they
radiate about the same.
4. See #3. If I had room for a bunch of radials to make the vertical
work properly, I'd have room for a real antenna.
5. Yagis do nicely. _IF_ you have the tower and rotor to put them on.
6. A 102' doublet with open wire feed line and a tuner works amazing
well and considering the cost difference is flat out outstanding.

#4. Having moved to a small rural town in central Texas, I have
a lot of room now living on 1/2 an acre.

I already had a used 40' tower and was given the tuner as a bribe to
try the 102' doublet. And I had a 500' spool of #14 THHN house wire
to play with.

Isn't half the fun of all this seeing what works well for you?

Jeff-1.0
wa6fwi

--
"Everything from Crackers to Coffins"

LDG Z11 Pro II tuner with an Icom IC-761
 

Jeffrey Angus wrote in
:

....
I just love wild goose chases, because in the end, you usually do
learn something useful in the process.

Yes, there is always a risk of that.

The auto tuner can be a path to hiding shortcomings in an antenna
system, in search of the holy grail, low VSWR.

Whilst you seem critical of the 4:1 voltage balun in the MFJ, it is my
perception that they are still the most popular balun. My theory on that
is that antenna systems that exhibit extreme impedance can often be
'matched' with that configuration, assisted by the loss in the balun.

It is an example of how the device's operation can be misunderstood.
There is little doubting the considerable anecdotal evidence that 4:1
voltage baluns work 'better', it is understanding what is meant by
'better' that is revealing.

That leads into the question of whether a 4:1 balun is 'better'.

If you were selling product, you would concentrate on the things that
deliver good VSWR, because that is all that is in the minds of most
buyers.

Owen

PS: for avoidance of doubt, nothing above should be interpreted to
recommend a 4:1 voltage balun or a 4:1 balun.

LDG Z11 Pro II tuner with an Icom IC-761
 

On 9/28/2011 7:31 PM, Owen Duffy wrote:
The auto tuner can be a path to hiding shortcomings in an antenna
system, in search of the holy grail, low VSWR.

This is a 102' doublet with 40' of open wire balanced feed line.
Except for the input of the tuner looking like 50 ohms to make the
transmitter happy, there is no such thing as "low VSWR" on this
type of antenna.

Whilst you seem critical of the 4:1 voltage balun in the MFJ, it is my
perception that they are still the most popular balun. My theory on that
is that antenna systems that exhibit extreme impedance can often be
'matched' with that configuration, assisted by the loss in the balun.

It is an example of how the device's operation can be misunderstood.
There is little doubting the considerable anecdotal evidence that 4:1
voltage baluns work 'better', it is understanding what is meant by
'better' that is revealing.

Actually, the MFJ 949b Versa Tuner has an internal 4:1 voltage balun.
The reason for that is simple. One large toroid and you're done. There
isn't room inside the case for a 4:1 current balun.

If you disconnect the open wire line from the internal voltage balun
in an MFJ tuner and replace it with an external current balun you will
find that the tuning of the match on the tuner is a lot smoother as
opposed to almost erratic. (But still obtainable.)

Due to the location of my station on the 2nd floor over looking a
covered porch, having a "good RF ground" is not going to happen.
The current balun forces the antenna and feed line into a truly
balanced condition. No ground needed, other than a proper bonding
of all the related equipment to a common reference in the station.

The whole purpose of the tuner is to allow the transmitter to see
a 50 ohm unbalanced load that it was designed for. Accomplishing
that, allows the most power to be transferred to the antenna. The
102' doublet with open wire line seems to do a remarkable job at
radiating. (And equally well at receiving.)

That leads into the question of whether a 4:1 balun is 'better'.

Better than what? A 1:1 balun or none at all, which seems to be
the selling point of the G5RV antenna and it's clones.

Jeff-1.0
wa6fwi

--
"Everything from Crackers to Coffins"

LDG Z11 Pro II tuner with an Icom IC-761
 

Jeffrey Angus wrote in news:j60h8s$ao0$1@dont-
email.me:

On 9/28/2011 7:31 PM, Owen Duffy wrote:
The auto tuner can be a path to hiding shortcomings in an antenna
system, in search of the holy grail, low VSWR.

This is a 102' doublet with 40' of open wire balanced feed line.
Except for the input of the tuner looking like 50 ohms to make the
transmitter happy, there is no such thing as "low VSWR" on this
type of antenna.

Well to "make the transmitter happy" is jsut the new language for low
VSWR.

... There
isn't room inside the case for a 4:1 current balun.

But there is probably room for an effective 1:1 Current Balun.


If you disconnect the open wire line from the internal voltage balun
in an MFJ tuner and replace it with an external current balun you will
find that the tuning of the match on the tuner is a lot smoother as
opposed to almost erratic. (But still obtainable.)

Ok, so in your experience, you haven't yet come across a load that could
be matched with the voltage balun, but not with an external current
balun.

Due to the location of my station on the 2nd floor over looking a
covered porch, having a "good RF ground" is not going to happen.
The current balun forces the antenna and feed line into a truly
balanced condition.

Ideal conditions like "forces" and "truly balanced" don't often exist in
the real world. It would be of more interest if you had measured and
reported the differential and common mode current at various
frequencies.

The whole purpose of the tuner is to allow the transmitter to see
a 50 ohm unbalanced load that it was designed for. Accomplishing
that, allows the most power to be transferred to the antenna. The

Yes. It is the meaning of "most" that is relevant. Most doesn't need to
mean 100%, or close to it, you make compromises for frequency agility
and multiband use, but "most" is often unknown. Perhaps some DX QSL
cards can substitute.

102' doublet with open wire line seems to do a remarkable job at
radiating. (And equally well at receiving.)

Yes, they can be a good antenna, but it is not a no-brainer.

For example, a correspondent recently reported problems with just such a
thing on 40m. Turns out his feed line length was such that at 800W into
the feed line, the voltage between the wires was some 4000+V and was
causing flashovers in a 3kW rated ATU. In this case, I recommended that
since he could not lengthen or shorten the feed line enough, that he
shorten the antenna so solve the problem.

He had previously smoked up a CWS Bytemark 5kW rated current balun on
80m with another antenna, caused by unlucky feed line length.


That leads into the question of whether a 4:1 balun is 'better'.

Better than what? A 1:1 balun or none at all,

1:1.

4:1 reduces the voltage impressed on the ATU components, which is good
for high impedance loads, and poor for low impedance loads.

There is no simple thing that always works best on a random set of loads
(which is the case for many multi band antennas).

which seems to be
the selling point of the G5RV antenna and it's clones.

Perhaps to some. There is good argument for use of a balun with a G5RV
and not-balanced transmitter. Varney conceded that in one of his later
articles. Most people who are adament about what Varney did or did not
describe have not read his articles. Antenna manufacturers are not a
good source of factual information.

Owen

LDG Z11 Pro II tuner with an Icom IC-761
 

On 9/28/2011 8:54 PM, Owen Duffy wrote:
Jeffrey wrote in news:j60h8s$ao0$1@dont-
email.me:

On 9/28/2011 7:31 PM, Owen Duffy wrote:
The auto tuner can be a path to hiding shortcomings in an antenna
system, in search of the holy grail, low VSWR.

This is a 102' doublet with 40' of open wire balanced feed line.
Except for the input of the tuner looking like 50 ohms to make the
transmitter happy, there is no such thing as "low VSWR" on this
type of antenna.

Well to "make the transmitter happy" is jsut the new language for low
VSWR.

You're missing the point. The "Holy Grail" is low VSWR at the antenna.
Obviously having the tuner present a nice resistive 50 ohm load to a
transmitter designed to be loaded with a resistive 50 ohm load is a
"Good thing(tm)".

But with a random length, i.e. non-resonant, antenna, VSWR at the
antenna is not a meaningful term.

... There
isn't room inside the case for a 4:1 current balun.

But there is probably room for an effective 1:1 Current Balun.

But my point was MFJ chose to use a voltage balun for two reasons.
They're cheaper and they still work to a fashion.

Ok, so in your experience, you haven't yet come across a load that could
be matched with the voltage balun, but not with an external current
balun.

Not yet. If it matches at all with one, it will match with the other.
The difference being that the current balun results in much less
erratic/sudden/critical tuning of the antenna tuner itself.

Due to the location of my station on the 2nd floor over looking a
covered porch, having a "good RF ground" is not going to happen.
The current balun forces the antenna and feed line into a truly
balanced condition.

Ideal conditions like "forces" and "truly balanced" don't often exist in
the real world. It would be of more interest if you had measured and
reported the differential and common mode current at various
frequencies.

Um, actually, yes they do. That's the whole point of a current mode
balun.

The whole purpose of the tuner is to allow the transmitter to see
a 50 ohm unbalanced load that it was designed for. Accomplishing
that, allows the most power to be transferred to the antenna. The

Yes. It is the meaning of "most" that is relevant. Most doesn't need to
mean 100%, or close to it, you make compromises for frequency agility
and multiband use, but "most" is often unknown. Perhaps some DX QSL
cards can substitute.

As an example then. How about working RA3DA in a pileup competing with
the "big guns" in New York running at or above the legal limit? Sure
I didn't get him on the first call, but I did it running under 100 watts
and into a $25 antenna.

102' doublet with open wire line seems to do a remarkable job at
radiating. (And equally well at receiving.)

Yes, they can be a good antenna, but it is not a no-brainer.

For example, a correspondent recently reported problems with just such a
thing on 40m. Turns out his feed line length was such that at 800W into
the feed line, the voltage between the wires was some 4000+V and was
causing flashovers in a 3kW rated ATU. In this case, I recommended that
since he could not lengthen or shorten the feed line enough, that he
shorten the antenna so solve the problem.

He had previously smoked up a CWS Bytemark 5kW rated current balun on
80m with another antenna, caused by unlucky feed line length.

See above. Why is it that hams seem to think they absolutely need to run
800 (or more) watts of power?

That leads into the question of whether a 4:1 balun is 'better'.

Better than what? A 1:1 balun or none at all,

1:1.

4:1 reduces the voltage impressed on the ATU components, which is good
for high impedance loads, and poor for low impedance loads.

There is no simple thing that always works best on a random set of loads
(which is the case for many multi band antennas).

All I've said is that this appears to work perfectly for me.
In the time honored tradition of Usenet "Your mileage may vary."

which seems to be
the selling point of the G5RV antenna and it's clones.

Perhaps to some. There is good argument for use of a balun with a G5RV
and not-balanced transmitter. Varney conceded that in one of his later
articles. Most people who are adament about what Varney did or did not
describe have not read his articles. Antenna manufacturers are not a
good source of factual information.

You're hear equally unsubstantiated claims about how well an off center
fed Windom antenna works with no tuner as well.

Jeff-1.0
wa6fwi

--
"Everything from Crackers to Coffins"

LDG Z11 Pro II tuner with an Icom IC-761
 

"Jeff Liebermann" wrote in message
...

... am now a practicing member of the Cult of
75 ohms. The difference is subtle. While worship of the 50 ohm idol
results in the maximum power transfer, the change to 75 ohms results
in minimum coax loss and somewhat easier antenna design. However, the
major benefit is it allows one to minimize the tithe paid to vendors
as CATV coax is cheap and readily available. I suggest you consider a
religious conversion.

Yes. Somebody in this group (you, maybe) previously promoted 75 ohm cable.
This past spring, I was modeling my 20m Field Day dipole, varying size and
height for best pattern shape and minimum VSWR. At optimum, it had almost
exactly 75 ohm feedpoint impedance. Having plenty of TV coax, I didn't
hesitate to go with it. The antenna worked wonderfully well at FD.
Transmitter seemed to like it just fine.

"Sal"

LDG Z11 Pro II tuner with an Icom IC-761
 

"Sal" wrote in :

Yes. Somebody in this group (you, maybe) previously promoted 75 ohm
cable. This past spring, I was modeling my 20m Field Day dipole,
varying size and height for best pattern shape and minimum VSWR. At
optimum, it had almost exactly 75 ohm feedpoint impedance. Having
plenty of TV coax, I didn't hesitate to go with it. The antenna
worked wonderfully well at FD. Transmitter seemed to like it just
fine.

Sal, you will have discovered that the feed point impedance of a half
wave dipole at resonance is dependent on height above ground, type of
soil etc.

This need not be a choice between 50 ohms and 75 ohms.

My 40m inverted V dipole uses 75 ohm feedline (RG6), and the impedance
looking into the feedline is close to 50+j0. Dipole height was
determined prior to design of the matching system (ie height was not
constrained by the matching solution, rather the height set a
requirement for the matching solution). The transmitter has its rated
load impedance, the feedline is efficient and inexpensive. There is a
W2DU style choke balun near the feedpoint, and measured common mode
current is quite low.

Of course, the feedline has standing waves, and the dipole is not
resonant, to be frowned upon by some (many?). The antenna system can be
readily modelled, and it has higher efficiency than a resonant half wave
with comparable coax (say RG8X), indistinguisable pattern, marginally
higher gain.

Owen




"Sal"

LDG Z11 Pro II tuner with an Icom IC-761
 

On Wed, 28 Sep 2011 23:26:24 -0700, "Sal" wrote:

"Jeff Liebermann" wrote in message
.. .

... am now a practicing member of the Cult of
75 ohms. The difference is subtle. While worship of the 50 ohm idol
results in the maximum power transfer, the change to 75 ohms results
in minimum coax loss and somewhat easier antenna design. However, the
major benefit is it allows one to minimize the tithe paid to vendors
as CATV coax is cheap and readily available. I suggest you consider a
religious conversion.

Yes. Somebody in this group (you, maybe) previously promoted 75 ohm cable.
This past spring, I was modeling my 20m Field Day dipole, varying size and
height for best pattern shape and minimum VSWR. At optimum, it had almost
exactly 75 ohm feedpoint impedance. Having plenty of TV coax, I didn't
hesitate to go with it. The antenna worked wonderfully well at FD.
Transmitter seemed to like it just fine.

Probably me. I tend to promote the use of 75 ohm coax and systems.
Most of the coax cables to my rooftop antenna farm are 75 ohms. The
justification was convenience and price. I obtained five 1000ft rolls
of RG6a/u mutations (some with messenger wire), and some used hard
line, and couldn't resist using it. The only problems seem to be
getting accurate readings on my test equipment and having enough
F-to-N or F-to-BNC adapters.
http://www.qsl.net/n9zia/wireless/75_ohm_hardline.html

Note that using 75 ohm coax on a VHF/UHF repeater is a really bad
idea. Duplexers, isolators, circulators, cavities, and such are very
sensitive to mismatch. For repeaters, use only 50 ohms.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

LDG Z11 Pro II tuner with an Icom IC-761
 

On Wed, 28 Sep 2011 19:26:49 -0500, Jeffrey Angus wrote:


3. Vertical antennas load nicely. So do Bird Termalines. And they
radiate about the same.
4. See #3. If I had room for a bunch of radials to make the vertical
work properly, I'd have room for a real antenna.


I have an MFJ-928 ATU at the feed point of an elevated 43' vertical, with
a half dozen radials of various random lengths. It works great for
30/20/17/15. It starts making significant multiple lobes above 21 MHz.
I'm going to try a coil for 80.

LDG Z11 Pro II tuner with an Icom IC-761
 

On Wed, 28 Sep 2011 21:22:55 -0500, Jeffrey Angus
wrote:

But my point was MFJ chose to use a voltage balun for two reasons.
They're cheaper

What is the price differential in winding one wire outside the core,
instead of winding it inside the core? Such "savings" accrue only in
the production run of millions of units.

and they still work to a fashion.

If both sides are unbalanced - you mean that fashion?

MFJ is not making a killing on this particular poor winding (OK, call
it historical inertia) practice, and their market for these internal
BalUns is dipoles, not monopoles.

73's
Richard Clark, KB7QHC

LDG Z11 Pro II tuner with an Icom IC-761
 

Richard Clark wrote in
:

....
MFJ is not making a killing on this particular poor winding (OK, call
it historical inertia) practice, and their market for these internal
BalUns is dipoles, not monopoles.

Hi Richard,

I see MFJ getting mention, and whilst they may deserve a bit of a
flogging for some things, I spring to their defence on this occasion.

MFJ make the claim "More hams use MFJ-949s than any other antenna tuner
in the world!" and gauging from questions in online fora, they are
indeed popular, the claim may be correct.

The MFJ949E uses a Ruthroff voltage balun.

I have measured the balun losses in my '949E, and they are as I
discussed in the general case earlier, quite high on high impedance
loads. Anyone with a rudimentary knowledge of balun design would
understand that, but there are those who apparently live in an ideal who
would refute it.

The simple explanation is that most loss in practical ferrite cored
baluns usually results from losses in the core material. The losses in
the core material are related to flux density, which in a Ruthroff
voltage balun is roughly proportion to the differential voltage, and in
a Guanella current balun is roughly proportional to common mode current.
There is no reason to think that these two different types of baluns
would have identical losses.

The MFJ949E could easily be reconfigured as a Guanella 1:1 balun by
changing its end connections, but that does not make it an optimally
designed current balun. I haven't done it, and so cannot comment
further. I cannot see how the cost of manufacturing it wired as a
current balun would be any different.

I think that it is the buyers who determine the market, and savvy
sellers cater to the buyer's wants.

While anecdotal evidence abounds that 4:1 voltage baluns match up
extreme loads better, and users mostly arent't interested in finding the
root cause of the problem and fixing it, voltage baluns will be seen by
most buyers and savvy sellers as the solution.

A good demonstration of the credibility of anecodotal evidence is the
massive online support for the Array Solutions 4:1 Ruthroff voltage
balun / ZeroFive unloaded vertical combination. The configuration drives
high common mode on the coax feed line. (I should note that the sellers
recommendation has recently changed to an unun.)

MFJ is no doubt one of the savvy sellers. They do BTW have some higher
end ATUs with 1:1 current balun, as does the Ameritron label for those
who want a current balun.

My own view is that achievement of highest choking impedance in a
current balun is assisted by minimising stray capacitance to 'ground',
so I would prefer to put a current balun in a non-conductive box,
outside the ATU, on a foot of coax to the ATU. (This is one reason why I
haven't tried converting my '949E to current balun connection, the
windings are quite close to grounded metal and I expect stray
capacitance to ground is higher than desirable.)

Owen

LDG Z11 Pro II tuner with an Icom IC-761
 

On Thu, 29 Sep 2011 21:06:40 +0000 (UTC), Owen Duffy
wrote:

My own view is that achievement of highest choking impedance in a
current balun is assisted by minimising stray capacitance to 'ground',
so I would prefer to put a current balun in a non-conductive box,
outside the ATU, on a foot of coax to the ATU. (This is one reason why I
haven't tried converting my '949E to current balun connection, the
windings are quite close to grounded metal and I expect stray
capacitance to ground is higher than desirable.)

Hi Owen,

The internal modification would also demand a balanced tuner topology,
and not the garden variety pi configuration. Your stating stray
capacitance, coupling to ground, etc. is a preface to this.

Put simply, and as described, the 949E and its ilk are lumped
transmission line UnUn transformers. You might salvage the box in a
re-design, but it would require gutting the entire interior circuitry.

The 974 attempts to do this:
http://www.mfjenterprises.com/pdffiles/MFJ-974HB.pdf
and by their stated intentions, they are aware of the design issues.

73's
Richard Clark, KB7QHC

LDG Z11 Pro II tuner with an Icom IC-761
 

Richard Clark wrote in
:

....
The 974 attempts to do this:
http://www.mfjenterprises.com/pdffiles/MFJ-974HB.pdf
and by their stated intentions, they are aware of the design issues.

I am sceptical of the "true balanced tuner" approach.

For one thing, I do not recall having ever seen measurement of the
common mode impedance reported.

If the objective is current balance, high common mode impedance is
essential.

Some folk seem to think that symmetric design is the sure path to
success, but it isn't. If you take a 1:1 Guanella with extremely high
choking impedance, the currents in its output wires will be almost
perfectly balanced, irrespective of the voltage from each terminal to
ground. If you placed 10pF of capacitance from each terminal to ground,
you appear to have preserved symmetry, but the currents in those
capacitors will not be equal unless the load is symmetric. In cases
where the currents in the balun wires are almost equal and the currents
in the capacitances I mentioned are not equal, then those capacitances
have probably compromised common mode impedance.

Most implementations of a "true balanced tuner" have large stray
capacitance from each side to chassis.

But, savvy sellers will offer them to the people who are attracted by
the concept of a "true balanced tuner".

The joke of balun offerings is those designs purported to work well on
isolated loads. If the concept of the load is the overly simplistic two
terminal network, and it is isolated from ground, clearly current into
one terminal MUST equal current out of the other terminal, no balun is
required.

Owen

LDG Z11 Pro II tuner with an Icom IC-761
 

On 9/28/2011 10:46 AM, Jeffrey Angus wrote:
It comes with an adapter cable for Icom radios, but it's a
4-pin Molex connector and the manual doesn't show what the
connections/signals are for the radio.

Multiple Homer Simpson "Do-oh!" moments.

LDG was kind enough to supply me with the application note for
the interface cable.

I have two Icom radios. An IC-761 with an internal tuner and an
IC-726 designed to use with an external tuner. The IC-726 has the
mating 4-pin Molex connector.

The two signals are essentially a "request to tune" and an "tune
complete". The IC-726 has a TUNE button on the front panel for
telling the external tuner to do it's thing. (By the way, I do
have the matching AT-150 auto-tuner for the IC-726.)

All three of the tuners, the IC-761 internal, IC-726 external and
LDG have an SO-239 connector for the output and would require an
external balun to connect to an open wire balanced feed line.

The reason I was using the MFJ Versa Tuner with the IC-761 was
fairly simple. It has an internal 4:1 balun and connections for
open wire balanced feed lines.

Since I had to purchase a balun to use the LDG tuner I realized
that "Oh, I can use the Icom tuners with the balun as well."
That was my first "Do-oh!" moment.

Subsequently on researching the interface signals to/from the
LDG I realized that the IC-761 doesn't have a TUNE button or the
signals externally because the tuner is already inside the radio.
That was my second "Do-oh!" moment.

Once the MFJ 4:1 current balun I ordered arrives, the only question
that remains is whether or not the specified matching range of the
Icom tuners is sufficient to deal with my antenna system.

The Icom tuners are specified at 16.7 to 150 ohms.
The LDG Z11 Pro II is specified as 2-1000 ohms.
Oddly enough, the MFJ Versa Tuner has no specified range.

Jeff-1.0
wa6fwi

--
"Everything from Crackers to Coffins"

LDG Z11 Pro II tuner with an Icom IC-761
 

Jeffrey Angus wrote in news:j64hp4$i7g$1@dont-
email.me:

The two signals are essentially a "request to tune" and an "tune
complete".

That is not quite correct.

Though the protocol is not published by Icom, and the implementation varies
a little from radio to radio, the four wires are usually labelled and none
are "tune complete".

Owen

LDG Z11 Pro II tuner with an Icom IC-761
 

Jeffrey Angus wrote in news:j64hp4$i7g$1@dont-
email.me:

The Icom tuners are specified at 16.7 to 150 ohms.
The LDG Z11 Pro II is specified as 2-1000 ohms.
Oddly enough, the MFJ Versa Tuner has no specified range.

Impedance is not a simple scalar quantity as expressed above. The
'specification' is incomplete, you would need to ask the sellers what
they meant.

If for example, they mean the R component only, do they imply that X
must be zero, or that X can be any value?

If they mean the magnitude, do they imply that any angle of impedance is
acceptable?

Also missing is any bounds on efficiency.

I have heard from time to time on air, OMs boast that their tuner is so
good, they have matched it up with no antenna plugged in. Obviously,
efficiency is zero in that case. A tuner with lower internal losses
might not achieve the same feat.

Owen

LDG Z11 Pro II tuner with an Icom IC-761
 

On 9/30/2011 2:04 PM, Owen Duffy wrote:
Jeffrey wrote in news:j64hp4$i7g$1@dont-
email.me:

The two signals are essentially a "request to tune" and an "tune
complete".

That is not quite correct.

Did you miss the word essentially?

Since it bothers you. From LDG "Start Line." Ground this from an
external switch or open collector to initiate a tuning sequence by
the external tuner.

And "Key Line" This is similar to a PTT line to the transmitter,
but in this case tells the transmitter (which is capable of doing
it) to, regardless of mode, transmit a low lever CW carrier.

When the key line changes state because of a request to tune, it
turns on the transmitter. When tuning is complete, the key line
toggles back to it's normal state.

Though the protocol is not published by Icom, and the implementation varies
a little from radio to radio, the four wires are usually labelled and none
are "tune complete".

If you put an indicator such as an LED on the key line watching it
change state is a pretty good indication of "I'm tuning" and "Tune
complete" regardless of what it's called.

Jeff

--
"Everything from Crackers to Coffins"

LDG Z11 Pro II tuner with an Icom IC-761
 

On 9/30/2011 3:03 PM, Owen Duffy wrote:
Jeffrey wrote in news:j64hp4$i7g$1@dont-
email.me:

The Icom tuners are specified at 16.7 to 150 ohms.
The LDG Z11 Pro II is specified as 2-1000 ohms.
Oddly enough, the MFJ Versa Tuner has no specified range.

Impedance is not a simple scalar quantity as expressed above. The
'specification' is incomplete, you would need to ask the sellers what
they meant.

If for example, they mean the R component only, do they imply that X
must be zero, or that X can be any value?

If they mean the magnitude, do they imply that any angle of impedance is
acceptable?

Do you just like to argue? These are published specifications from
the manufacturer. If you have an issues with the validity of their
claims, take it up with them.

I suspect both Icom and LDG took the time to play with resistive
loads to verify the tuning range. If that is the case, then yes,
it's a simple scalar quantity. I doubt they took the time to fiddle
around adding a reactive components to the test loads otherwise they
would haved published a Smith Chart with a "We can match anything
within these bounds" as the specification for tuning range.

Also missing is any bounds on efficiency.

I have heard from time to time on air, OMs boast that their tuner is so
good, they have matched it up with no antenna plugged in. Obviously,
efficiency is zero in that case. A tuner with lower internal losses
might not achieve the same feat.

I am aware that a frightening majority of licensed amateurs wouldn't
be able to pour **** out of a boot with the instructions printed on
the heel. Perhaps you're unaware tha I'm not one of them.

Jeff-1.0
wa6fwi

--
"Everything from Crackers to Coffins"

LDG Z11 Pro II tuner with an Icom IC-761
 

Jeffrey Angus wrote in
:

On 9/30/2011 2:04 PM, Owen Duffy wrote:
Jeffrey wrote in news:j64hp4$i7g$1@dont-
email.me:

The two signals are essentially a "request to tune" and an "tune
complete".

That is not quite correct.

Did you miss the word essentially?

Since it bothers you. From LDG "Start Line." Ground this from an
external switch or open collector to initiate a tuning sequence by
the external tuner.

And "Key Line" This is similar to a PTT line to the transmitter,
but in this case tells the transmitter (which is capable of doing
it) to, regardless of mode, transmit a low lever CW carrier.

When the key line changes state because of a request to tune, it
turns on the transmitter. When tuning is complete, the key line
toggles back to it's normal state.

Though the protocol is not published by Icom, and the implementation
varies a little from radio to radio, the four wires are usually
labelled and none are "tune complete".

If you put an indicator such as an LED on the key line watching it
change state is a pretty good indication of "I'm tuning" and "Tune
complete" regardless of what it's called.

The /KEY line can be used to initiate a tune carrier, it is used to
sustain the tune carrier until the tx aborts or the tuner ends the
process, and it is used by the tuner to signal whether the tune was or
was not successful.

Owen