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"

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

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

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"

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

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

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"

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"

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.

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"