LDG antenna tuner with 132 foot balanced dipole similar to a G5RV antenna

[Ron Midwin-3]

I recently bought an LDG AT600 Pro Automatic Tuner.

I seem to be able to get a low VSWR on 80 & 40 meters, but on 20, 15, & 10
meters the best it will do is ~ 1.8:1.

My "G5RV" (It's really a Van Gordon 80 meter all bander fed with 450 ladder
line, 33 feet long, and then transitions to coax thru a 1:1 choke balun;
coax is ~ 6 feet long.

Has anyone found a configuration that works better on all the bands?

Previously I have been using an MFJ 962D manual tuner that is able to tune
down below 1.2:1 on all bands.

AE6RH
K3 S/N 1997

--
Ron Midwin
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[ke9uw]

Well...maybe the component sizes in the automatic LDG design are coarse enough that your 1:1 values of components is not acheived.
Of course a manual tuner has infinite values of continuously variable capacitor and  inductor values. Thus it's easier to acheive 1:1.
But anyway, why worry about 1.8:1? And how are you measuring SWR? Accurately?
So many variables, and 1.8:1 not mattering, I would forget any concern about it.

Chuck, KE9UW
aka Jack, BMW Motorcycles BMWMOA #224

________________________________________
From: [hidden email] [[hidden email]] on behalf of Ron Midwin [[hidden email]]
Sent: Friday, October 26, 2012 7:42 AM
To: [hidden email]
Subject: [Elecraft] LDG antenna tuner with 132 foot balanced dipole similar     to a G5RV antenna

I recently bought an LDG AT600 Pro Automatic Tuner.

I seem to be able to get a low VSWR on 80 & 40 meters, but on 20, 15, & 10
meters the best it will do is ~ 1.8:1.

My "G5RV" (It's really a Van Gordon 80 meter all bander fed with 450 ladder
line, 33 feet long, and then transitions to coax thru a 1:1 choke balun;
coax is ~ 6 feet long.

Has anyone found a configuration that works better on all the bands?

Previously I have been using an MFJ 962D manual tuner that is able to tune
down below 1.2:1 on all bands.

AE6RH
K3 S/N 1997

--
Ron Midwin
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[Rick Stealey]

Why not just help the tuner out a little?  Put some inductance in series with the
center conductor and see if it likes that better.  If that doesn't work put some C
in series and adjust it.  Or some C across the line.  Or some L across the line.
Or some L in series and C across the line.  You get the idea, move the impedance as seen
by the tuner to something it can deal with.

Rick  K2XT
     
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[David Cutter]

Try an off-centre-fed dipole, you'll have lower swr at the antenna to start
with meaning less loss in your matching unit to get it to 50ohms.  Running
modest power you can use coax and the right balun and choke at the feedpoint
if you can stand the weight up there.  An inverted V configuration holding
the balun on a pole works well.  See this:
http://www.dj0ip.de/antennas/off-center-fed-dipole/80m-ocf/


David
G3UNA


> Has anyone found a configuration that works better on all the bands?
> > AE6RH
> Ron Midwin
>
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[David Bunte]

Ron -

This is not an area where I have much experience, but with 450 ohm ladder
line I would have thought you would use something other than a 1:1 balun.

A few years ago I experimented briefly with an 80 meter dipole, fed with
450 ohm ladder line.  I tried it with a 1:1 balun and with a 4:1 balun.  An
LDG AT-7000 tuned it very easily on 80 through 10 meters while using the
4:1 balun... but had trouble on some bands with the 1:1 balun.

Dave - K9FN


On Fri, Oct 26, 2012 at 8:42 AM, Ron Midwin <[hidden email]> wrote:

> I recently bought an LDG AT600 Pro Automatic Tuner.
>
> I seem to be able to get a low VSWR on 80 & 40 meters, but on 20, 15, & 10
> meters the best it will do is ~ 1.8:1.
>
> My "G5RV" (It's really a Van Gordon 80 meter all bander fed with 450 ladder
> line, 33 feet long, and then transitions to coax thru a 1:1 choke balun;
> coax is ~ 6 feet long.
>
> Has anyone found a configuration that works better on all the bands?
>
> Previously I have been using an MFJ 962D manual tuner that is able to tune
> down below 1.2:1 on all bands.
>
> AE6RH
> K3 S/N 1997
>
> --
> Ron Midwin
> ______________________________________________________________
> 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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[Mike WA8BXN]

Ron ---
 
Does the tuner have a setting as to how low an SWR it should attempt to get?
Some say anything below 2:1 is fine. A trick I have found with some auto
tuners is to try tuning at different places in a given band. If you can get
a "better" match at some points, go back to where you want to actually be
and see if it now finds a better match.
 
73 - Mike WA8BXN
 
 
 
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[Barry K3NDM]

Ron,
     The antenna you have is basically a good one. The problem you get
into is that it's really an 80 meter dipole being used on all bands.
This has been a popular configuration for many years. The issue is NOT
SWR. The issue is transmission line loss in a high SWR situation. To
avoid high losses is to use open wire feeds/window line, etc, to the
point you get near to your tuner; this is usually at the exterior wall
of your house or a window. At that point, you would need to install a
4:1 CURRENT balun. This will do two things. It will keep the feed SWR to
a level that should be no problem for your tuner and maintain that there
will be no RF current on the exterior of the coax coming into the house;
voltage baluns don't always work well if the SWR gets to high. This
should work well for you.

     I use have used this configuration over the years and it has worked
for me and other hams that have tried it. Don't get too spun up if the
SWR does not get to 1:1. The issue will be is the SWR within the
requirements for your transmitter. If the transmitter doesn't care and
you do as I suggest, you don't care either. Happy DXing!!!

73,
Barry
K3NDM


On 10/26/2012 8:42 AM, Ron Midwin wrote:

> I recently bought an LDG AT600 Pro Automatic Tuner.
>
> I seem to be able to get a low VSWR on 80 & 40 meters, but on 20, 15, & 10
> meters the best it will do is ~ 1.8:1.
>
> My "G5RV" (It's really a Van Gordon 80 meter all bander fed with 450 ladder
> line, 33 feet long, and then transitions to coax thru a 1:1 choke balun;
> coax is ~ 6 feet long.
>
> Has anyone found a configuration that works better on all the bands?
>
> Previously I have been using an MFJ 962D manual tuner that is able to tune
> down below 1.2:1 on all bands.
>
> AE6RH
> K3 S/N 1997
>

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[N5GE-2]

All,

There's a trick I learned from an antenna engineer acquaintance
recently for tuning 450 ohm feedline's with a 1:1 balun with 50 ohm
coax feeding the TX.

Here it is:

1. Assemble three RG11 coax lengths.  One coax 6 feet 7 inches long,
one coax 6 feet long and one coax 9 feet long.  From these three coax
lengths you can test with four different lengths of 75 ohm coax;
6' 7", 12' 7", 15' 7" and 21' 7".

2. Beginning with the 6' 7" cable and connect the coax between the
balun and the 50 ohm feed line, repeat the test below with each of
the lengths above.  Connect the cables with double female connectors.

3. If you have an analyzer (MFJ analyzers work fine for this) that
gives the Rs, Xs and SWR go to step 4; If you don't go to step 6.  If
you have an AIM 4170 analyzer, you are in luck.  The AIM allows you
to do single shot analysis of a single frequency, displaying more
information than you need for this test.

4. Record the Rs, Xs and SWR of each combination at the frequency you
are interested in.  A spread sheet makes this a little less tedious.

5. After recording the calculate the SWR the tuner will see with the
following rules:

Disregard Xs.

If the Rs is greater than 50 divide the Rs by 50.
if the Rs is less than 50 divide 50 by the Rs.

The result will be the SWR the tuner is working against when
searching for a match.  

In my case I am looking for a calculated SWR lower than 10:1 to help
my KAT500 tuner find an acceptable match to my KPA500 and NVIS Loop,
which works on all amateur bands for close in Non-DX rag chew
communications.


6. You can still do the test, but you will need to do it by testing
with the tuner for the best combination of matches at each frequency
of interest.

If you are going to do the tests, remember to use the MINIMUM power
your tuner can tune with and allow time for your rig to cool down
between tests.

7.  When you have completed your tests measure the length of the
joined test coaxes, including the double female connectors, and make
a piece of RG11 that length.

DISCLAMER:  I'm not a real technical guy and probably don't know as
much antenna theory as many of you, but what I have described worked
for me.  Your experience may not be the same.

Amateur Radio Operator N5GE
ARRL Lifetime Member
QCWA Lifetime Member



On Fri, 26 Oct 2012 05:42:20 -0700, Ron Midwin
<[hidden email]> wrote:

>I recently bought an LDG AT600 Pro Automatic Tuner.
>
>I seem to be able to get a low VSWR on 80 & 40 meters, but on 20, 15, & 10
>meters the best it will do is ~ 1.8:1.
>
>My "G5RV" (It's really a Van Gordon 80 meter all bander fed with 450 ladder
>line, 33 feet long, and then transitions to coax thru a 1:1 choke balun;
>coax is ~ 6 feet long.
>
>Has anyone found a configuration that works better on all the bands?
>
>Previously I have been using an MFJ 962D manual tuner that is able to tune
>down below 1.2:1 on all bands.
>
>AE6RH
>K3 S/N 1997

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[af9w]

What is the significance of using RG11 75 ohm coax vs 50 ohm?  Sorry if this is a dumb question.

Bob AF9W


On Oct 26, 2012, at 10:39 AM, N5GE wrote:

> All,
>
> There's a trick I learned from an antenna engineer acquaintance
> recently for tuning 450 ohm feedline's with a 1:1 balun with 50 ohm
> coax feeding the TX.
>
> Here it is:
>
> 1. Assemble three RG11 coax lengths.  One coax 6 feet 7 inches long,
> one coax 6 feet long and one coax 9 feet long.  From these three coax
> lengths you can test with four different lengths of 75 ohm coax;
> 6' 7", 12' 7", 15' 7" and 21' 7".
>
> 2. Beginning with the 6' 7" cable and connect the coax between the
> balun and the 50 ohm feed line, repeat the test below with each of
> the lengths above.  Connect the cables with double female connectors.
>
> 3. If you have an analyzer (MFJ analyzers work fine for this) that
> gives the Rs, Xs and SWR go to step 4; If you don't go to step 6.  If
> you have an AIM 4170 analyzer, you are in luck.  The AIM allows you
> to do single shot analysis of a single frequency, displaying more
> information than you need for this test.
>
> 4. Record the Rs, Xs and SWR of each combination at the frequency you
> are interested in.  A spread sheet makes this a little less tedious.
>
> 5. After recording the calculate the SWR the tuner will see with the
> following rules:
>
> Disregard Xs.
>
> If the Rs is greater than 50 divide the Rs by 50.
> if the Rs is less than 50 divide 50 by the Rs.
>
> The result will be the SWR the tuner is working against when
> searching for a match.  
>
> In my case I am looking for a calculated SWR lower than 10:1 to help
> my KAT500 tuner find an acceptable match to my KPA500 and NVIS Loop,
> which works on all amateur bands for close in Non-DX rag chew
> communications.
>
>
> 6. You can still do the test, but you will need to do it by testing
> with the tuner for the best combination of matches at each frequency
> of interest.
>
> If you are going to do the tests, remember to use the MINIMUM power
> your tuner can tune with and allow time for your rig to cool down
> between tests.
>
> 7.  When you have completed your tests measure the length of the
> joined test coaxes, including the double female connectors, and make
> a piece of RG11 that length.
>
> DISCLAMER:  I'm not a real technical guy and probably don't know as
> much antenna theory as many of you, but what I have described worked
> for me.  Your experience may not be the same.
>
> Amateur Radio Operator N5GE
> ARRL Lifetime Member
> QCWA Lifetime Member
>
>
>
> On Fri, 26 Oct 2012 05:42:20 -0700, Ron Midwin
> <[hidden email]> wrote:
>
>> I recently bought an LDG AT600 Pro Automatic Tuner.
>>
>> I seem to be able to get a low VSWR on 80 & 40 meters, but on 20, 15, & 10
>> meters the best it will do is ~ 1.8:1.
>>
>> My "G5RV" (It's really a Van Gordon 80 meter all bander fed with 450 ladder
>> line, 33 feet long, and then transitions to coax thru a 1:1 choke balun;
>> coax is ~ 6 feet long.
>>
>> Has anyone found a configuration that works better on all the bands?
>>
>> Previously I have been using an MFJ 962D manual tuner that is able to tune
>> down below 1.2:1 on all bands.
>>
>> AE6RH
>> K3 S/N 1997
>
> ______________________________________________________________
> 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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[W Paul Mills]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Impedance matching. See
<http://www.fourier-series.com/rf-concepts/smithchart.html> May be
more than you wanted to know, but is easy to follow Smith Chart
Tutorials. And does explain why you might want to do this.

On 10/26/2012 01:23 PM, Bob Stephens wrote:
> What is the significance of using RG11 75 ohm coax vs 50 ohm?
> Sorry if this is a dumb question.
>
> Bob AF9W
>
>


- --
/*************************************************
* Amateur Radio Station AC0HY                    *
* W. Paul Mills         SN807                    *
* Assistant EC Alpha-1 ARES Shawnee/Wabunsee, KS *
* President Kaw Valley Amateur Radio Club        *
*************************************************/
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Version: GnuPG v1.4.11 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://www.enigmail.net/

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[Jim Wiley]

All other things being equal, 75-ohm cable has less loss per foot than
50-ohm cable.  This assumes that the cables being compared have the same
diameter, length, operating frequency, etc.  This is the primary reason
that cable TV systems, telco inside-plant cabling, and other similar
applications use 70-ohm cable.  Maximum power handling is obtained by
using 30-ohm cable.  50-ohm cable represents the approximate mean
between lowest loss and best power handling.


- Jim, KL7CC



On 10/26/2012 10:23 AM, Bob Stephens wrote:

> What is the significance of using RG11 75 ohm coax vs 50 ohm?  Sorry if this is a dumb question.
>
> Bob AF9W
>
>
> On Oct 26, 2012, at 10:39 AM, N5GE wrote:
>
>> All,
>>
>> There's a trick I learned from an antenna engineer acquaintance
>> recently for tuning 450 ohm feedline's with a 1:1 balun with 50 ohm
>> coax feeding the TX.
>>
>> Here it is:
>>
>> 1. Assemble three RG11 coax lengths.  One coax 6 feet 7 inches long,
>> one coax 6 feet long and one coax 9 feet long.  From these three coax
>> lengths you can test with four different lengths of 75 ohm coax;
>> 6' 7", 12' 7", 15' 7" and 21' 7".
>>
>> 2. Beginning with the 6' 7" cable and connect the coax between the
>> balun and the 50 ohm feed line, repeat the test below with each of
>> the lengths above.  Connect the cables with double female connectors.
>>
>> 3. If you have an analyzer (MFJ analyzers work fine for this) that
>> gives the Rs, Xs and SWR go to step 4; If you don't go to step 6.  If
>> you have an AIM 4170 analyzer, you are in luck.  The AIM allows you
>> to do single shot analysis of a single frequency, displaying more
>> information than you need for this test.
>>
>> 4. Record the Rs, Xs and SWR of each combination at the frequency you
>> are interested in.  A spread sheet makes this a little less tedious.
>>
>> 5. After recording the calculate the SWR the tuner will see with the
>> following rules:
>>
>> Disregard Xs.
>>
>> If the Rs is greater than 50 divide the Rs by 50.
>> if the Rs is less than 50 divide 50 by the Rs.
>>
>> The result will be the SWR the tuner is working against when
>> searching for a match.
>>
>> In my case I am looking for a calculated SWR lower than 10:1 to help
>> my KAT500 tuner find an acceptable match to my KPA500 and NVIS Loop,
>> which works on all amateur bands for close in Non-DX rag chew
>> communications.
>>
>>
>> 6. You can still do the test, but you will need to do it by testing
>> with the tuner for the best combination of matches at each frequency
>> of interest.
>>
>> If you are going to do the tests, remember to use the MINIMUM power
>> your tuner can tune with and allow time for your rig to cool down
>> between tests.
>>
>> 7.  When you have completed your tests measure the length of the
>> joined test coaxes, including the double female connectors, and make
>> a piece of RG11 that length.
>>
>> DISCLAMER:  I'm not a real technical guy and probably don't know as
>> much antenna theory as many of you, but what I have described worked
>> for me.  Your experience may not be the same.
>>
>> Amateur Radio Operator N5GE
>> ARRL Lifetime Member
>> QCWA Lifetime Member
>>
>>
>>
>> On Fri, 26 Oct 2012 05:42:20 -0700, Ron Midwin
>> <[hidden email]> wrote:
>>
>>> I recently bought an LDG AT600 Pro Automatic Tuner.
>>>
>>> I seem to be able to get a low VSWR on 80 & 40 meters, but on 20, 15, & 10
>>> meters the best it will do is ~ 1.8:1.
>>>
>>> My "G5RV" (It's really a Van Gordon 80 meter all bander fed with 450 ladder
>>> line, 33 feet long, and then transitions to coax thru a 1:1 choke balun;
>>> coax is ~ 6 feet long.
>>>
>>> Has anyone found a configuration that works better on all the bands?
>>>
>>> Previously I have been using an MFJ 962D manual tuner that is able to tune
>>> down below 1.2:1 on all bands.
>>>
>>> AE6RH
>>> K3 S/N 1997
>> ______________________________________________________________
>> 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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>

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[Jim Wiley]

Sorry, meant to say 75-ohm, not 70-ohm in my previous post.

- Jim, KL7CC


On 10/26/2012 10:23 AM, Bob Stephens wrote:

> What is the significance of using RG11 75 ohm coax vs 50 ohm?  Sorry if this is a dumb question.
>
> Bob AF9W
>
>
> On Oct 26, 2012, at 10:39 AM, N5GE wrote:
>
>> All,
>>
>> There's a trick I learned from an antenna engineer acquaintance
>> recently for tuning 450 ohm feedline's with a 1:1 balun with 50 ohm
>> coax feeding the TX.
>>
>> Here it is:
>>
>> 1. Assemble three RG11 coax lengths.  One coax 6 feet 7 inches long,
>> one coax 6 feet long and one coax 9 feet long.  From these three coax
>> lengths you can test with four different lengths of 75 ohm coax;
>> 6' 7", 12' 7", 15' 7" and 21' 7".
>>
>> 2. Beginning with the 6' 7" cable and connect the coax between the
>> balun and the 50 ohm feed line, repeat the test below with each of
>> the lengths above.  Connect the cables with double female connectors.
>>
>> 3. If you have an analyzer (MFJ analyzers work fine for this) that
>> gives the Rs, Xs and SWR go to step 4; If you don't go to step 6.  If
>> you have an AIM 4170 analyzer, you are in luck.  The AIM allows you
>> to do single shot analysis of a single frequency, displaying more
>> information than you need for this test.
>>
>> 4. Record the Rs, Xs and SWR of each combination at the frequency you
>> are interested in.  A spread sheet makes this a little less tedious.
>>
>> 5. After recording the calculate the SWR the tuner will see with the
>> following rules:
>>
>> Disregard Xs.
>>
>> If the Rs is greater than 50 divide the Rs by 50.
>> if the Rs is less than 50 divide 50 by the Rs.
>>
>> The result will be the SWR the tuner is working against when
>> searching for a match.
>>
>> In my case I am looking for a calculated SWR lower than 10:1 to help
>> my KAT500 tuner find an acceptable match to my KPA500 and NVIS Loop,
>> which works on all amateur bands for close in Non-DX rag chew
>> communications.
>>
>>
>> 6. You can still do the test, but you will need to do it by testing
>> with the tuner for the best combination of matches at each frequency
>> of interest.
>>
>> If you are going to do the tests, remember to use the MINIMUM power
>> your tuner can tune with and allow time for your rig to cool down
>> between tests.
>>
>> 7.  When you have completed your tests measure the length of the
>> joined test coaxes, including the double female connectors, and make
>> a piece of RG11 that length.
>>
>> DISCLAMER:  I'm not a real technical guy and probably don't know as
>> much antenna theory as many of you, but what I have described worked
>> for me.  Your experience may not be the same.
>>
>> Amateur Radio Operator N5GE
>> ARRL Lifetime Member
>> QCWA Lifetime Member
>>
>>
>>
>> On Fri, 26 Oct 2012 05:42:20 -0700, Ron Midwin
>> <[hidden email]> wrote:
>>
>>> I recently bought an LDG AT600 Pro Automatic Tuner.
>>>
>>> I seem to be able to get a low VSWR on 80 & 40 meters, but on 20, 15, & 10
>>> meters the best it will do is ~ 1.8:1.
>>>
>>> My "G5RV" (It's really a Van Gordon 80 meter all bander fed with 450 ladder
>>> line, 33 feet long, and then transitions to coax thru a 1:1 choke balun;
>>> coax is ~ 6 feet long.
>>>
>>> Has anyone found a configuration that works better on all the bands?
>>>
>>> Previously I have been using an MFJ 962D manual tuner that is able to tune
>>> down below 1.2:1 on all bands.
>>>
>>> AE6RH
>>> K3 S/N 1997
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[Barry K3NDM]

The significance of the 75 Ohm line is a matching section that
introduces a reciprocal impedance that brings the SWR to 1:1, or nearly
so. However, this approach does not address the balanced to unbalanced
issue. And, this is generally a one band match. A 1:1 choke type balun
will still be needed.

The approach may be technically correct, but it is more work than I feel
it it is worth. I still suggest the simpler approach I noted earlier as
it does work and requires zero engineering knowledge. You just hook up
the 450 Ohm ladder line to the antenna on one end and the other goes to
the 4:1 current balun. Low loss coax is connected between the tuner and
the balun. The operator just tunes the affair until he gets to an
acceptable SWR. Nothing else is required, no fiddling around, just
operation. 100 feet of 450 line and a few feet of coax will yield losses
in the  1-1.5 db range with SWRs up to about around 10:1. This just
isn't worth all of the fiddling, IMHO. I try to always adhere to the
KISS principle.

73,
Barry
K3NDM



On 10/26/2012 2:23 PM, Bob Stephens wrote:

> What is the significance of using RG11 75 ohm coax vs 50 ohm?  Sorry if this is a dumb question.
>
> Bob AF9W
>
>
> On Oct 26, 2012, at 10:39 AM, N5GE wrote:
>
>> All,
>>
>> There's a trick I learned from an antenna engineer acquaintance
>> recently for tuning 450 ohm feedline's with a 1:1 balun with 50 ohm
>> coax feeding the TX.
>>
>> Here it is:
>>
>> 1. Assemble three RG11 coax lengths.  One coax 6 feet 7 inches long,
>> one coax 6 feet long and one coax 9 feet long.  From these three coax
>> lengths you can test with four different lengths of 75 ohm coax;
>> 6' 7", 12' 7", 15' 7" and 21' 7".
>>
>> 2. Beginning with the 6' 7" cable and connect the coax between the
>> balun and the 50 ohm feed line, repeat the test below with each of
>> the lengths above.  Connect the cables with double female connectors.
>>
>> 3. If you have an analyzer (MFJ analyzers work fine for this) that
>> gives the Rs, Xs and SWR go to step 4; If you don't go to step 6.  If
>> you have an AIM 4170 analyzer, you are in luck.  The AIM allows you
>> to do single shot analysis of a single frequency, displaying more
>> information than you need for this test.
>>
>> 4. Record the Rs, Xs and SWR of each combination at the frequency you
>> are interested in.  A spread sheet makes this a little less tedious.
>>
>> 5. After recording the calculate the SWR the tuner will see with the
>> following rules:
>>
>> Disregard Xs.
>>
>> If the Rs is greater than 50 divide the Rs by 50.
>> if the Rs is less than 50 divide 50 by the Rs.
>>
>> The result will be the SWR the tuner is working against when
>> searching for a match.
>>
>> In my case I am looking for a calculated SWR lower than 10:1 to help
>> my KAT500 tuner find an acceptable match to my KPA500 and NVIS Loop,
>> which works on all amateur bands for close in Non-DX rag chew
>> communications.
>>
>>
>> 6. You can still do the test, but you will need to do it by testing
>> with the tuner for the best combination of matches at each frequency
>> of interest.
>>
>> If you are going to do the tests, remember to use the MINIMUM power
>> your tuner can tune with and allow time for your rig to cool down
>> between tests.
>>
>> 7.  When you have completed your tests measure the length of the
>> joined test coaxes, including the double female connectors, and make
>> a piece of RG11 that length.
>>
>> DISCLAMER:  I'm not a real technical guy and probably don't know as
>> much antenna theory as many of you, but what I have described worked
>> for me.  Your experience may not be the same.
>>
>> Amateur Radio Operator N5GE
>> ARRL Lifetime Member
>> QCWA Lifetime Member
>>
>>
>>
>> On Fri, 26 Oct 2012 05:42:20 -0700, Ron Midwin
>> <[hidden email]> wrote:
>>
>>> I recently bought an LDG AT600 Pro Automatic Tuner.
>>>
>>> I seem to be able to get a low VSWR on 80 & 40 meters, but on 20, 15, & 10
>>> meters the best it will do is ~ 1.8:1.
>>>
>>> My "G5RV" (It's really a Van Gordon 80 meter all bander fed with 450 ladder
>>> line, 33 feet long, and then transitions to coax thru a 1:1 choke balun;
>>> coax is ~ 6 feet long.
>>>
>>> Has anyone found a configuration that works better on all the bands?
>>>
>>> Previously I have been using an MFJ 962D manual tuner that is able to tune
>>> down below 1.2:1 on all bands.
>>>
>>> AE6RH
>>> K3 S/N 1997
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>>
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>> Please help support this email list: http://www.qsl.net/donate.html
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[Don Wilhelm-4]

David,

I have seen several responses that suggest changes to your antenna
setup, but not one that I can "warm up to".

The choice of a 1:1 balun vs. a 4:1 balun depends on the feedpoint
impedance and has nothing to do with the fact that the characteristic
impedance of the ladder line is 450 ohms - the impedance at the shack
end of that feedline is what is important. If you do not understand what
is going on, I direct you to the antenna article on my website
www.w3fpr.com,

I would strongly suggest that you measure the electrical length of the
feedline plus the length of one side of the radiator for all bands of
interest.  Avoid those sum lengths that are close to a multiple of a
half wavelength.  Most autotuners do not have the range to work into the
high impedance presented by a half wavelength - that goes for 1/2 of a
dipole (plus feedline) as well as for an end fed antenna.

73,
Don W3FPR

On 10/26/2012 10:23 AM, David Bunte wrote:

> Ron -
>
> This is not an area where I have much experience, but with 450 ohm ladder
> line I would have thought you would use something other than a 1:1 balun.
>
> A few years ago I experimented briefly with an 80 meter dipole, fed with
> 450 ohm ladder line.  I tried it with a 1:1 balun and with a 4:1 balun.  An
> LDG AT-7000 tuned it very easily on 80 through 10 meters while using the
> 4:1 balun... but had trouble on some bands with the 1:1 balun.
>
> Dave - K9FN
>
>

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