Discussion:
[OT] High SWR on 20 and 40
(too old to reply)
djmd
2010-01-15 20:32:03 UTC
Permalink
Hello,

I have been trying to troubleshoot my antenna system, and have been trying
to avoid the dreaded "high swr" post, but I've run out of ideas, so I'm
turning here.

First let me explain my system. 67' dipole fed by 16' of window line. That's
connected to an Elecraft balun. From the balun, there's a short piece of
coax going to a barrel and into the basement (through a piece of cement
backerboard. From inside the basement, there is another piece of coax, about
12', connected to the barrel, and going up into the bedroom directly to a K2
with an autotuner.

Before the K2, I was using a Yaesu FT840 with an MFJ tuner. After tweaking
the window line length and the actual length of the dipole, I never really
had a problem with SWR (well, according to what the MFJ was saying, which
may or may not be totally accurate.) Usually 1.5:1 or under on all bands.

With the K2/KAT2 in place, the SWR reported by the tuner is all over the
place. The only one that gets less than 1.5:1 is 30m. Most bands are pretty
random, anywhere from 3:1 to 7:1. However, on 20 and 40, it generally does
not get below 9.9:1.

I've tried 4 different lengths of coax between the barrel (inside) and the
rig... 3', 6', 12' 20'. I've tried a couple different lengths between the
balun and the barrel on the outside.

When I attach the balun directly to the K2 I get <1.3:1 on all bands (most
are 1:1.) With a short piece of coax between the rig and the balun, I get
the same results. I've also attached my dummy load to the barrel on the
outside of the house, and tested it from the shack, and I saw 1:1 no
problem.

I totally understand the concept that if "A" works and "B" works, "A+B"
doesn't necessarily work. I understand it's a whole system. But I've tried
so many different combinations of coax on each side, and don't understand
why my SWR is basically infinity:1 on 20 and 40, when they seemed to match
reasonably with the old system. I have not tried different lengths of window
line between the dipole due to the fact that I had it perfectly trimmed for
my old system. But I have plenty of it and would be open to trying anything.

Just trying to get the most I can out of my modest 10W. :) Any suggestions
would be appreciated!

73,

Dave
K8DJW
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Don Wilhelm
2010-01-15 20:45:26 UTC
Permalink
Dave,

Is that a 1:1 balun or a 4:1 balun. Usually a 1:1 works better, but
whichever balun you are using, try the other one and see what happens.
Do you have an antenna analyzer? or can you borrow one? If so, what is
the impedance at the end of the coax? Both the resistive and reactive
components please - just the SWR does not provide much information on
how to advise you to proceed.

You may be better off eliminating the coax entirely and running the
window line all the way into the shack.
73,
Don W3FPR
Post by djmd
Hello,
I have been trying to troubleshoot my antenna system, and have been trying
to avoid the dreaded "high swr" post, but I've run out of ideas, so I'm
turning here.
First let me explain my system. 67' dipole fed by 16' of window line. That's
connected to an Elecraft balun. From the balun, there's a short piece of
coax going to a barrel and into the basement (through a piece of cement
backerboard. From inside the basement, there is another piece of coax, about
12', connected to the barrel, and going up into the bedroom directly to a K2
with an autotuner.
Before the K2, I was using a Yaesu FT840 with an MFJ tuner. After tweaking
the window line length and the actual length of the dipole, I never really
had a problem with SWR (well, according to what the MFJ was saying, which
may or may not be totally accurate.) Usually 1.5:1 or under on all bands.
With the K2/KAT2 in place, the SWR reported by the tuner is all over the
place. The only one that gets less than 1.5:1 is 30m. Most bands are pretty
random, anywhere from 3:1 to 7:1. However, on 20 and 40, it generally does
not get below 9.9:1.
I've tried 4 different lengths of coax between the barrel (inside) and the
rig... 3', 6', 12' 20'. I've tried a couple different lengths between the
balun and the barrel on the outside.
When I attach the balun directly to the K2 I get <1.3:1 on all bands (most
are 1:1.) With a short piece of coax between the rig and the balun, I get
the same results. I've also attached my dummy load to the barrel on the
outside of the house, and tested it from the shack, and I saw 1:1 no
problem.
I totally understand the concept that if "A" works and "B" works, "A+B"
doesn't necessarily work. I understand it's a whole system. But I've tried
so many different combinations of coax on each side, and don't understand
why my SWR is basically infinity:1 on 20 and 40, when they seemed to match
reasonably with the old system. I have not tried different lengths of window
line between the dipole due to the fact that I had it perfectly trimmed for
my old system. But I have plenty of it and would be open to trying anything.
Just trying to get the most I can out of my modest 10W. :) Any suggestions
would be appreciated!
73,
Dave
K8DJW
djmd
2010-01-16 00:34:38 UTC
Permalink
It's the BL-2 switched balun that I have been using, and have tried both
modes. Forgot that detail. I have also tried one of those baluns built from
PVC - can't remember the manufacturer. It's a 1:1 as well. Same results.

No analyzer yet, but I really should think about getting one. Planning on a
lot of antenna experimentation this year.

I have actually thought of eliminating the coax. I'm not sure if I can use
the same route as the coax, with the metal window frames, gas pipe, water
pipes, all nearby in the basement. But what about going right through the
brick? I would not be opposed to doing something like this.

And re: your follow up - all the testing was done with the KAT2. I have
never disconnected it.

I also should have mentioned that I do plan on using this antenna system
with my old radio as well. Only 10w on the K2, but 50 or so with the Yaesu
as well. (mostly digital and CW.)
Post by Don Wilhelm
Dave,
Is that a 1:1 balun or a 4:1 balun. Usually a 1:1 works better, but
whichever balun you are using, try the other one and see what happens.
Do you have an antenna analyzer? or can you borrow one? If so, what is
the impedance at the end of the coax? Both the resistive and reactive
components please - just the SWR does not provide much information on
how to advise you to proceed.
You may be better off eliminating the coax entirely and running the
window line all the way into the shack.
73,
Don W3FPR
Post by djmd
Hello,
I have been trying to troubleshoot my antenna system, and have been trying
to avoid the dreaded "high swr" post, but I've run out of ideas, so I'm
turning here.
First let me explain my system. 67' dipole fed by 16' of window line. That's
connected to an Elecraft balun. From the balun, there's a short piece of
coax going to a barrel and into the basement (through a piece of cement
backerboard. From inside the basement, there is another piece of coax, about
12', connected to the barrel, and going up into the bedroom directly to a K2
with an autotuner.
Before the K2, I was using a Yaesu FT840 with an MFJ tuner. After tweaking
the window line length and the actual length of the dipole, I never really
had a problem with SWR (well, according to what the MFJ was saying, which
may or may not be totally accurate.) Usually 1.5:1 or under on all bands.
With the K2/KAT2 in place, the SWR reported by the tuner is all over the
place. The only one that gets less than 1.5:1 is 30m. Most bands are pretty
random, anywhere from 3:1 to 7:1. However, on 20 and 40, it generally does
not get below 9.9:1.
I've tried 4 different lengths of coax between the barrel (inside) and the
rig... 3', 6', 12' 20'. I've tried a couple different lengths between the
balun and the barrel on the outside.
When I attach the balun directly to the K2 I get <1.3:1 on all bands (most
are 1:1.) With a short piece of coax between the rig and the balun, I get
the same results. I've also attached my dummy load to the barrel on the
outside of the house, and tested it from the shack, and I saw 1:1 no
problem.
I totally understand the concept that if "A" works and "B" works, "A+B"
doesn't necessarily work. I understand it's a whole system. But I've tried
so many different combinations of coax on each side, and don't understand
why my SWR is basically infinity:1 on 20 and 40, when they seemed to match
reasonably with the old system. I have not tried different lengths of window
line between the dipole due to the fact that I had it perfectly trimmed for
my old system. But I have plenty of it and would be open to trying anything.
Just trying to get the most I can out of my modest 10W. :) Any suggestions
would be appreciated!
73,
Dave
K8DJW
______________________________________________________________
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djmd
2010-01-16 00:39:22 UTC
Permalink
oh, and yes, I was definitely getting a 1:1 on the KAT2 between the radio and
the dummy load. I put the dummy load in at all points and saw 1:1.
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Don Wilhelm
2010-01-16 00:49:37 UTC
Permalink
Dave,

If you did not disconnect the KAT2, then please tell us the setup (all
the connections) when you have SWR readings below 1.5.
That may be capable of providing some sort of clue.

73,
Don W3FPR
Post by djmd
And re: your follow up - all the testing was done with the KAT2. I have
never disconnected it.
Post by Don Wilhelm
Dave,
Is that a 1:1 balun or a 4:1 balun. Usually a 1:1 works better, but
whichever balun you are using, try the other one and see what happens.
Do you have an antenna analyzer? or can you borrow one? If so, what is
the impedance at the end of the coax? Both the resistive and reactive
components please - just the SWR does not provide much information on
how to advise you to proceed.
You may be better off eliminating the coax entirely and running the
window line all the way into the shack.
73,
Don W3FPR
Post by djmd
Hello,
I have been trying to troubleshoot my antenna system, and have been trying
to avoid the dreaded "high swr" post, but I've run out of ideas, so I'm
turning here.
First let me explain my system. 67' dipole fed by 16' of window line. That's
connected to an Elecraft balun. From the balun, there's a short piece of
coax going to a barrel and into the basement (through a piece of cement
backerboard. From inside the basement, there is another piece of coax, about
12', connected to the barrel, and going up into the bedroom directly to a K2
with an autotuner.
Before the K2, I was using a Yaesu FT840 with an MFJ tuner. After tweaking
the window line length and the actual length of the dipole, I never really
had a problem with SWR (well, according to what the MFJ was saying, which
may or may not be totally accurate.) Usually 1.5:1 or under on all bands.
With the K2/KAT2 in place, the SWR reported by the tuner is all over the
place. The only one that gets less than 1.5:1 is 30m. Most bands are pretty
random, anywhere from 3:1 to 7:1. However, on 20 and 40, it generally does
not get below 9.9:1.
I've tried 4 different lengths of coax between the barrel (inside) and the
rig... 3', 6', 12' 20'. I've tried a couple different lengths between the
balun and the barrel on the outside.
When I attach the balun directly to the K2 I get <1.3:1 on all bands (most
are 1:1.) With a short piece of coax between the rig and the balun, I get
the same results. I've also attached my dummy load to the barrel on the
outside of the house, and tested it from the shack, and I saw 1:1 no
problem.
I totally understand the concept that if "A" works and "B" works, "A+B"
doesn't necessarily work. I understand it's a whole system. But I've tried
so many different combinations of coax on each side, and don't understand
why my SWR is basically infinity:1 on 20 and 40, when they seemed to match
reasonably with the old system. I have not tried different lengths of window
line between the dipole due to the fact that I had it perfectly trimmed for
my old system. But I have plenty of it and would be open to trying anything.
Just trying to get the most I can out of my modest 10W. :) Any suggestions
would be appreciated!
73,
Dave
K8DJW
______________________________________________________________
Elecraft mailing list
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djmd
2010-01-16 01:41:41 UTC
Permalink
Thanks Don. There are multiple scenarios.

1) K2 - BL2 - windowline - dipole

2) K2 - 2' Mini-RG8 - BL2 - windowline - dipole

3) K2 - 10' RG8 - BL2 - windowline - dipole

All coax is terminated PL-259, so there are BNC-SO239 adapters at the K2 and
Balun.

Where the system starts to fail is when I go from the K2, through any length
of coax, into a 4" barrel (entry point) , then to another short piece of
coax between the barrel and the balun. The only sort of testing I've done
through this barrel (it's going through cement backerboard) is attaching an
MFJ dummy load in place of the balun.

K2 - 10' RG8 - 4" barrel - 2' RG8 - Dummy Load

That's where I saw the 1:1 across the bands from the K2/KAT2. I suppose that
may not be a good enough test to give this part of the system a "thumbs up,"
but it's all I got at this point.

With the system in place right now (K2 - coax - barrel - coax - balun -
antenna) here's what I'm seeing on the KAT2 with the power set to 2.0w.

80m 8.3:1
40m 9.9:1
30m 1.3:1
20m 9.9:1
17m 6.3:1
15m 2.2:1
12m 1.0:1
10m 1.0:1
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djmd
2010-01-16 02:50:16 UTC
Permalink
Just one more quick note tonight. I put the W1 inline, and in most cases it's
reporting much higher SWRs than the KAT2 is. Particularly those 1:1s in the
high bands... the W1 is reporting >5.

I also attached the W1 between the K2 and the KAT2, and it none of the SWR
LEDs light up; I'm assuming this is to mean 1:1.

So, I'm a tad more confused now... but starting to think that it is indeed a
KAT2 issue.
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Guy Olinger K2AV
2010-01-16 04:48:00 UTC
Permalink
The 16 feet of window line makes me wonder if you're not trying to do
a half-size G5RV, but got the top dimensions wrong. It would be 51'
(instead of 67 which is REALLY bad on 20 meters), or a little longer,
say 54' if you wanted to load on 17m and 12m.

My K2/10 and the auto tuner will match most anything, but your lengths
are not anything I would do on purpose for multiband : >)
Post by Don Wilhelm
Dave,
If you did not disconnect the KAT2, then please tell us the setup (all
the connections) when you have SWR readings below 1.5.
That may be capable of providing some sort of clue.
73,
Don W3FPR
Post by djmd
And re: your follow up - all the testing was done with the KAT2. I have
never disconnected it.
Dave,
Is that a 1:1 balun or a 4:1 balun. ?Usually a 1:1 works better, but
whichever balun you are using, try the other one and see what happens.
Do you have an antenna analyzer? ?or can you borrow one? ?If so, what is
the impedance at the end of the coax? ?Both the resistive and reactive
components please - just the SWR does not provide much information on
how to advise you to proceed.
You may be better off eliminating the coax entirely and running the
window line all the way into the shack.
73,
Don W3FPR
Post by djmd
Hello,
I have been trying to troubleshoot my antenna system, and have been trying
to avoid the dreaded "high swr" post, but I've run out of ideas, so I'm
turning here.
First let me explain my system. 67' dipole fed by 16' of window line. That's
connected to an Elecraft balun. From the balun, there's a short piece of
coax going to a barrel and into the basement (through a piece of cement
backerboard. From inside the basement, there is another piece of coax, about
12', connected to the barrel, and going up into the bedroom directly to a K2
with an autotuner.
Before the K2, I was using a Yaesu FT840 with an MFJ tuner. After tweaking
the window line length and the actual length of the dipole, I never really
had a problem with SWR (well, according to what the MFJ was saying, which
may or may not be totally accurate.) Usually 1.5:1 or under on all bands.
With the K2/KAT2 in place, the SWR reported by the tuner is all over the
place. The only one that gets less than 1.5:1 is 30m. Most bands are pretty
random, anywhere from 3:1 to 7:1. However, on 20 and 40, it generally does
not get below 9.9:1.
I've tried 4 different lengths of coax between the barrel (inside) and the
rig... 3', 6', 12' 20'. I've tried a couple different lengths between the
balun and the barrel on the outside.
When I attach the balun directly to the K2 I get <1.3:1 on all bands (most
are 1:1.) With a short piece of coax between the rig and the balun, I get
the same results. I've also attached my dummy load to the barrel on the
outside of the house, and tested it from the shack, and I saw 1:1 no
problem.
I totally understand the concept that if "A" works and "B" works, "A+B"
doesn't necessarily work. I understand it's a whole system. But I've tried
so many different combinations of coax on each side, and don't understand
why my SWR is basically infinity:1 on 20 and 40, when they seemed to match
reasonably with the old system. I have not tried different lengths of window
line between the dipole due to the fact that I had it perfectly trimmed for
my old system. But I have plenty of it and would be open to trying anything.
Just trying to get the most I can out of my modest 10W. :) Any suggestions
would be appreciated!
73,
Dave
K8DJW
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Elecraft at mailman.qth.net
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djmd
2010-01-16 11:53:55 UTC
Permalink
Thanks for the input Guy,

Actually, the lengths are just a result of me trying to get this antenna
optimized for 40m with my Yaesu 840 and the MFJ unbalanced tuner. This is my
first HF antenna, and I never intended for it to be a true multibander. And
yes - it never performed well on 20m at all. I live on a small lot and can't
get anything too high, so it was just a means to get on the air. It did well
on 40m and 30m with the old setup, so more than anything, I am curious why
the K2/KAT2 can't seem to tune it up on 40.

40/30/20 is all I'm interested in right now, so perhaps the half G5RV might
be something I should explore?! I certainly would not be opposed to lopping
8 feet off each end of this antenna.

Thanks again!

Dave
Post by Guy Olinger K2AV
The 16 feet of window line makes me wonder if you're not trying to do
a half-size G5RV, but got the top dimensions wrong.
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Wes Stewart
2010-01-15 21:10:10 UTC
Permalink
I think he would be better off throwing away the window line and eliminating the tuner.

Cut the length of the dipole for resonance on 40M and then add a 20M dipole in parallel at the feed point. There will be some interaction, which can be lessened by orienting the dipoles at right angles to each other or at least getting some angular separation.

Conventional wisdom (not always correct) says to use a 1:1 current balun at the antenna.

With only 10W you don't want to be throwing it away in lossy tuners and mismatched transmission lines.

Wes N7WS

ps. The only tuner I use in my shack is the pi-net in my L4-B.
From: Don Wilhelm <w3fpr at embarqmail.com>
Subject: Re: [Elecraft] [OT] High SWR on 20 and 40
To: "djmd" <djmd at fuse.net>
Cc: elecraft at mailman.qth.net
Date: Friday, January 15, 2010, 1:45 PM
Dave,
Is that a 1:1 balun or a 4:1 balun.? Usually a 1:1
works better, but
whichever balun you are using, try the other one and see
what happens.
Do you have an antenna analyzer?? or can you borrow
one?? If so, what is
the impedance at the end of the coax?? Both the
resistive and reactive
components please - just the SWR does not provide much
information on
how to advise you to proceed.
You may be better off eliminating the coax entirely and
running the
window line all the way into the shack.
73,
Don W3FPR
Post by djmd
Hello,
I have been trying to troubleshoot my antenna system,
and have been trying
Post by djmd
to avoid the dreaded "high swr" post, but I've run out
of ideas, so I'm
Post by djmd
turning here.
First let me explain my system. 67' dipole fed by 16'
of window line. That's
Post by djmd
connected to an Elecraft balun. From the balun,
there's a short piece of
Post by djmd
coax going to a barrel and into the basement (through
a piece of cement
Post by djmd
backerboard. From inside the basement, there is
another piece of coax, about
Post by djmd
12', connected to the barrel, and going up into the
bedroom directly to a K2
Post by djmd
with an autotuner.
Before the K2, I was using a Yaesu FT840 with an MFJ
tuner. After tweaking
Post by djmd
the window line length and the actual length of the
dipole, I never really
Post by djmd
had a problem with SWR (well, according to what the
MFJ was saying, which
Post by djmd
may or may not be totally accurate.) Usually 1.5:1 or
under on all bands.
Post by djmd
With the K2/KAT2 in place, the SWR reported by the
tuner is all over the
Post by djmd
place. The only one that gets less than 1.5:1 is 30m.
Most bands are pretty
Post by djmd
random, anywhere from 3:1 to 7:1. However, on 20 and
40, it generally does
Post by djmd
not get below 9.9:1.
I've tried 4 different lengths of coax between the
barrel (inside) and the
Post by djmd
rig... 3', 6', 12' 20'. I've tried a couple different
lengths between the
Post by djmd
balun and the barrel on the outside.
When I attach the balun directly to the K2 I get
<1.3:1 on all bands (most
Post by djmd
are 1:1.) With a short piece of coax between the rig
and the balun, I get
Post by djmd
the same results. I've also attached my dummy load to
the barrel on the
Post by djmd
outside of the house, and tested it from the shack,
and I saw 1:1 no
Post by djmd
problem.
I totally understand the concept that if "A" works and
"B" works, "A+B"
Post by djmd
doesn't necessarily work. I understand it's a whole
system. But I've tried
Post by djmd
so many different combinations of coax on each side,
and don't understand
Post by djmd
why my SWR is basically infinity:1 on 20 and 40, when
they seemed to match
Post by djmd
reasonably with the old system. I have not tried
different lengths of window
Post by djmd
line between the dipole due to the fact that I had it
perfectly trimmed for
Post by djmd
my old system. But I have plenty of it and would be
open to trying anything.
Post by djmd
Just trying to get the most I can out of my modest
10W. :) Any suggestions
Post by djmd
would be appreciated!
73,
Dave
K8DJW
Daniel Paul Perez
2010-01-16 04:53:36 UTC
Permalink
Dave,

Thanks for posting this.

I'm going through the exact same exercise with my KX-1 KXAT1 and
Icom703+. Glad to know I'm not alone. The Icom is able to tune just
fine and when I switch the KX1 does not tune all bands ? not on 40M.
The KX1 tuner is optimized for shorter lengths of wire. I too wanted to
use one antenna for both radios. I wonder if the K2 is optimized for a
shorter wire? I find the more coax I insert between the 4:1 balun and
radio the better the Icom tunes and performs and the opposite for the
Elecraft -- it then loses 80, 40, 30 and barely tunes 20. It?s really
odd. I get perfect SWR with a dummy load and KX1.

I'll try a few things over the next few days per Elecraft. But
will be very interested in what you find. Is the window ladder line 450
ohm?

Does Elecraft give guidance on how the tuners are optimized?
Eighth to quarter wavelength?

I want to be sure as you do that the max power goes out.

Best,

Daniel ad1p
djmd
2010-01-16 12:09:42 UTC
Permalink
Hi Daniel!

I too have a KX1/AT1, and in fact, noticed this issue on the KX1 before I
was even done building the K2. I just hooked the KX1 back up, and I'm
getting nearly the same results.

40m 8.1:1
30m 1.3:1
20m infinity:1

It's been a while since I've used it outside, but I used to hook it up
directly to the dipole through the BL2 balun and I could get a great match
on 40m and 30m.

I am buying an antenna analyzer today. Not necessarily because I think it
will solve this problem (if it does, that's great!) but I'm long overdue for
one.

73,

K8DJW
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Don Wilhelm
2010-01-16 13:47:56 UTC
Permalink
Dave,

It is of great interest that your KX1 tuner could handle the tuning if
you connected it directly to the balun. Fact is that the KXAT1 range is
quite limited due to only having 3 inductors and 3 capacitors to switch
in and out trying to find a match - the KAT2 has 8 of each and has quite
a wide range.

What is the chance that you have a bad piece of coax or a bad barrel
adapter in the coax line? Has your coax outside gotten water inside
it? That is certainly a possibility if you did not seal the connectors
- low loss foam coax can soak up a lot of water.
Do you have a bad balun? (I had one that got water soaked this summer
and quit on me giving high SWR indications).
You might want to try a new length of coax without the balun - connect
the coax directly to the ladder line. If that works, try adding back
the balun, then add the original coax At some point, you will identify
what is failing.

73,
Don W3FPR
Post by djmd
Hi Daniel!
I too have a KX1/AT1, and in fact, noticed this issue on the KX1 before I
was even done building the K2. I just hooked the KX1 back up, and I'm
getting nearly the same results.
40m 8.1:1
30m 1.3:1
20m infinity:1
It's been a while since I've used it outside, but I used to hook it up
directly to the dipole through the BL2 balun and I could get a great match
on 40m and 30m.
I am buying an antenna analyzer today. Not necessarily because I think it
will solve this problem (if it does, that's great!) but I'm long overdue for
one.
73,
K8DJW
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Daniel Paul Perez
2010-01-16 05:02:32 UTC
Permalink
Dave,

Thanks for posting this.

I'm going through the exact same exercise with my KX-1 KXAT1 and
Icom703+. Glad to know I'm not alone. The Icom is able to tune just
fine and when I switch the KX1 does not tune all bands ? not on 40M.
The KX1 tuner is optimized for shorter lengths of wire. I too wanted to
use one antenna for both radios. I wonder if the K2 is optimized for a
shorter wire? I find the more coax I insert between the 4:1 balun and
radio the better the Icom tunes and performs and the opposite for the
Elecraft -- it then loses 80, 40, 30 and barely tunes 20. It?s really
odd. I get perfect SWR with a dummy load and KX1.

I'll try a few things over the next few days per Elecraft. But
will be very interested in what you find. Is the window ladder line 450
ohm?

Does Elecraft give guidance on how the tuners are optimized?
Eighth to quarter wavelength?

I want to be sure as you do that the max power goes out.

Best,

Daniel ad1p
David Y.
2010-01-16 14:16:31 UTC
Permalink
Hi Daniel and all,

I have all four Elecraft rigs, including internal ATU's. The ATU in the KX1
is the least effective of all of them. While my K2 and K3 ATU's can tune my
R7, which is optomized for around 7130 khz on 40 meters, to nearly "flat"
on each end of the band (the R7 has fairly sharp tuning on 40 meters), the
KX1 ATU struggles at each end of the band. I've borrowed a 2nd KX1, and
gotten much the same result, so I don't think it is just my particular ATU.

In such a small package, it's not hard to understand why the KX1 ATU might
not be nearly as versatile. The ATU in the K3 is the best of any internal
ATU I've ever had. The K2 ATU is also quite good. The ATU in my K1 does a
"fair" job, but I've always been somewhat suspect that I might have a small
problem with that ATU. Occasionally it acts like it doesn't want to
activate.

Since my R7 on 40 meters seems to be a good application for an ATU when
doing wide excursions on the band, maybe it would be interesting to see (and
plot) how each rig's ATU performs across the band. It's also interesting
(to me at least) that my K3 ATU will tune the R7 on 80 meters. The K2 might
do that, but I haven't tried it. Obviously the R7 is very inefficient on
75/80, but at least the radio seems happy.

The bottom line for me is that the KX1 ATU is useful, but not very wide
ranging. It may work better on some other types of antennas. I'm glad I
have it, but some situations probably require an outboard unit that is more
versatile. Since I use balanced feedline type antennas a lot when I am
portable, I usually have an outboard tuner for that reason. I really like
"Z" match tuners for QRP use. The NorCal BLT is a good one too.

Dave W7AQK


----- Original Message -----
From: "Daniel Paul Perez" <daniel.perez at fshsociety.org>
To: <elecraft at mailman.qth.net>
Sent: Friday, January 15, 2010 10:02 PM
Subject: Re: [Elecraft] [OT] High SWR on 20 and 40



Dave,

Thanks for posting this.

I'm going through the exact same exercise with my KX-1 KXAT1 and
Icom703+. Glad to know I'm not alone. The Icom is able to tune just
fine and when I switch the KX1 does not tune all bands ? not on 40M.
The KX1 tuner is optimized for shorter lengths of wire. I too wanted to
use one antenna for both radios. I wonder if the K2 is optimized for a
shorter wire? I find the more coax I insert between the 4:1 balun and
radio the better the Icom tunes and performs and the opposite for the
Elecraft -- it then loses 80, 40, 30 and barely tunes 20. It?s really
odd. I get perfect SWR with a dummy load and KX1.

I'll try a few things over the next few days per Elecraft. But
will be very interested in what you find. Is the window ladder line 450
ohm?

Does Elecraft give guidance on how the tuners are optimized?
Eighth to quarter wavelength?

I want to be sure as you do that the max power goes out.

Best,

Daniel ad1p



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Don Wilhelm
2010-01-16 14:36:22 UTC
Permalink
Dave and all,

Are you aware that you can use both tuners "in tandem"? You can set the
manual tuner quickly for a close match and then let the internal tuner
refine the match.

For instance, you have an antenna that is difficult to match, but you
already have a list of setting for a close match (less than 3:1) on the
manual tuner for that antenna - just turn to those settings and then let
the KX1, K1, K2, K3 tuner clean up for a very ow SWR.

73,
Don W3FPR
Post by David Y.
The bottom line for me is that the KX1 ATU is useful, but not very wide
ranging. It may work better on some other types of antennas. I'm glad I
have it, but some situations probably require an outboard unit that is more
versatile. Since I use balanced feedline type antennas a lot when I am
portable, I usually have an outboard tuner for that reason. I really like
"Z" match tuners for QRP use. The NorCal BLT is a good one too.
Dave W7AQK
Brian Alsop
2010-01-16 15:17:50 UTC
Permalink
Of course two tuners doubles the tuner losses. Tuner losses amount to
10 to 15% per tuner, sometimes higher. If you're not folding back power
after the first tuner does its match and it's under about 1.8, don't
bother. There is nothing real to be gained.

If you need both tuners, the real need is for a better matched antenna
or a single tuner with a wider matching range.

73 de Brian/K3KO
Post by Don Wilhelm
Dave and all,
Are you aware that you can use both tuners "in tandem"? You can set the
manual tuner quickly for a close match and then let the internal tuner
refine the match.
For instance, you have an antenna that is difficult to match, but you
already have a list of setting for a close match (less than 3:1) on the
manual tuner for that antenna - just turn to those settings and then let
the KX1, K1, K2, K3 tuner clean up for a very ow SWR.
73,
Don W3FPR
Post by David Y.
The bottom line for me is that the KX1 ATU is useful, but not very wide
ranging. It may work better on some other types of antennas. I'm glad I
have it, but some situations probably require an outboard unit that is more
versatile. Since I use balanced feedline type antennas a lot when I am
portable, I usually have an outboard tuner for that reason. I really like
"Z" match tuners for QRP use. The NorCal BLT is a good one too.
Dave W7AQK
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Jim Miller
2010-01-16 15:23:01 UTC
Permalink
There is one benefit to a low match at the tranceiver. Most builtin power
meters are only accurate at 1:1. If you're trying to ensure you are "qrp"
and your transmitter measures output power to maintain that level you need
to ensure the match is correct.

jim ab3cv
Guy Olinger K2AV
2010-01-16 17:08:00 UTC
Permalink
There are many kinds and configurations of tuners, each one having
differing weak spots. There is not a single one outside of military
prices which does not have impedance ranges that are inappropriate for
the particular tuner design. Some tuners use CONTINUOUSLY variable
inductors AND capacitors to get around most of those "blind spots" but
there will still be matching points where it can't be brought down.
Often where circulating currents in that particular design MUST become
so high as to destroy components or waste half the power or more .

You can fit a hundred KX1's inside of the case of many tuners, so in
the KX1, the overriding issue is to use a design that CAN be
MINIATURIZED. That you have an auto tuner AT ALL in a KX1 is already
on the wonderful side of remarkable. To criticize it for not having
the range of a larger tuner with continuously variable components
seems unfairly critical to an extreme.

Tuners designed with switched components necessarily have a "lumpy"
performance but are the only method that can be made small enough for
internal use in a K2 or KX1, etc. None of these that I have seen will
deal with 1000+ ohm loads.

But the real root of the calling these no-match ranges a "problem"
seems a lacking in basic antenna understanding. ANY wire with ANY
feedpoint will have harmonically related frequency ranges where the
feed impedance can go into the thousands of ohms. If you have put up a
wire antenna for all band use and haven't MEASURED what these are for
your antenna on intended frequencies of use, you are quite short of
putting forward a reasonable case for a tuner not working or having
poor design.

Loading any antenna to all ham bands in any location with any
miscellaneous conductors around REMAINS a very sticky problem. For
sure, NOT among god-given rights, is that any auto-tuner in any rig
(including a KX1) must able to tune ANY antenna to ALL bands in any
circumstance and provide a 1:1 SWR.

There is an antenna, manufactured for decades by B&W, that is a folded
dipole with with a feedline on one wire at the center, and a high
power RF termination resistor on the other wire at center. The
termination resistor prevents the nodes of very high feed Z, reducing
the range of Z extremes to values easily matched across the spectrum.

There are tens of thousands of these antennas in use over the world at
military sites, embassies and other installations where frequency
agility is important, particularly in spread-spectrum modes. The
"wasted" watts on certain frequency ranges are made up for by removing
the high-Z nodes at the feedpoint. That this is an entirely successful
approach and design fulfilling a continuing need is proven by
continued sales to this day.

Designing a single antenna that does not have Hi-Z nodes on
wide-spread wanted frequencies is a pastime that goes back to the dawn
of radio, and continues to this day. G5RV's, 86 and 43 foot end-fed
wires, off-center fed dipoles, are but a few of the answers, and each
has characteristics here or there that make it unusable or less
desireable in a given circumstance.

If you can't match it, START WITH THE ANTENNA, THEN THE FEEDLINE.
Random collections of elevated wire and feedline usually DON'T work
everywhere. But if it doesn't work and you don't get it, you have a
challenging and possibly highly entertaining education in front of
you. Something like learning to play chess. Join the century-old
society of antenna designers and tinkerers going back to Marconi and
beyond.

Dumping it on tuner manufactures is just so ......

Never mind.

73, Guy.
Don Wilhelm
2010-01-16 15:58:51 UTC
Permalink
Brian,

While all that is true, the operating convenience that is afforded by
using that method can be more significant than the added loss - it all
depends...

An L network usually is a low loss tuner. All the Elecraft tuners are
of the L network type, as are many other 'auto-tuners'
The old link coupled tuners such as the Johnson Matchbox are also very
low loss. The popular "T" networks can be very bad with multiple
matching points, but they do have a very large range and bandswitch easily.

Using a manual tuner to bring the SWR on a difficult to feed antenna
down to a reasonable level and then refining the match with an internal
auto-tuner provides the same convenience as operating with only the
autotuner - and the manual tuner can be in a remote location. After
all, matching networks at an antenna can be thought of as "manual tuner"
whose tuning is not changed - it brings the impedance down to a level
where it can be easily fed with coax, and a tuner in the shack provides
the final match required for large excursions across the band.

Yes, at HF, an SWR of 2:1 or less does not increase the coax loss enough
to be significant. At VHF and UHF it does make a difference because the
additional loss caused by SWR grows as the matched line loss increases,
and matched line losses increase with increasing frequency.

73,
Don W3FPR
Post by Brian Alsop
Of course two tuners doubles the tuner losses. Tuner losses amount to
10 to 15% per tuner, sometimes higher. If you're not folding back power
after the first tuner does its match and it's under about 1.8, don't
bother. There is nothing real to be gained.
If you need both tuners, the real need is for a better matched antenna
or a single tuner with a wider matching range.
73 de Brian/K3KO
Post by Don Wilhelm
Dave and all,
Are you aware that you can use both tuners "in tandem"? You can set the
manual tuner quickly for a close match and then let the internal tuner
refine the match.
For instance, you have an antenna that is difficult to match, but you
already have a list of setting for a close match (less than 3:1) on the
manual tuner for that antenna - just turn to those settings and then let
the KX1, K1, K2, K3 tuner clean up for a very ow SWR.
73,
Don W3FPR
Post by David Y.
The bottom line for me is that the KX1 ATU is useful, but not very wide
ranging. It may work better on some other types of antennas. I'm glad I
have it, but some situations probably require an outboard unit that is more
versatile. Since I use balanced feedline type antennas a lot when I am
portable, I usually have an outboard tuner for that reason. I really like
"Z" match tuners for QRP use. The NorCal BLT is a good one too.
Dave W7AQK
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Julius Fazekas n2wn
2010-01-16 14:33:46 UTC
Permalink
Dave,

Have you tried putting a dummy load in line and seeing if the tuner will
tune 1:1 with it?

This might tell you if the problem is in the tuner. You could also place the
load further along the coax and see if the problem disappears.

My KAT2 can tune almost anything it seems, but it is possible that your
bridge diodes got zapped and that would cause problems.

73,
Julius
n2wn
Post by djmd
Hello,
I have been trying to troubleshoot my antenna system, and have been trying
to avoid the dreaded "high swr" post, but I've run out of ideas, so I'm
turning here.
First let me explain my system. 67' dipole fed by 16' of window line.
That's connected to an Elecraft balun. From the balun, there's a short
piece of coax going to a barrel and into the basement (through a piece of
cement backerboard. From inside the basement, there is another piece of
coax, about 12', connected to the barrel, and going up into the bedroom
directly to a K2 with an autotuner.
Before the K2, I was using a Yaesu FT840 with an MFJ tuner. After tweaking
the window line length and the actual length of the dipole, I never really
had a problem with SWR (well, according to what the MFJ was saying, which
may or may not be totally accurate.) Usually 1.5:1 or under on all bands.
With the K2/KAT2 in place, the SWR reported by the tuner is all over the
place. The only one that gets less than 1.5:1 is 30m. Most bands are
pretty random, anywhere from 3:1 to 7:1. However, on 20 and 40, it
generally does not get below 9.9:1.
I've tried 4 different lengths of coax between the barrel (inside) and the
rig... 3', 6', 12' 20'. I've tried a couple different lengths between the
balun and the barrel on the outside.
When I attach the balun directly to the K2 I get <1.3:1 on all bands (most
are 1:1.) With a short piece of coax between the rig and the balun, I get
the same results. I've also attached my dummy load to the barrel on the
outside of the house, and tested it from the shack, and I saw 1:1 no
problem.
I totally understand the concept that if "A" works and "B" works, "A+B"
doesn't necessarily work. I understand it's a whole system. But I've tried
so many different combinations of coax on each side, and don't understand
why my SWR is basically infinity:1 on 20 and 40, when they seemed to match
reasonably with the old system. I have not tried different lengths of
window line between the dipole due to the fact that I had it perfectly
trimmed for my old system. But I have plenty of it and would be open to
trying anything.
Just trying to get the most I can out of my modest 10W. :) Any suggestions
would be appreciated!
73,
Dave
K8DJW
-----
Julius Fazekas
N2WN

Tennessee Contest Group
http://www.k4ro.net/tcg/index.html

Tennessee QSO Party
http://www.tnqp.org/

Elecraft K2/100 #4455
Elecraft K3/100 #366
Elecraft K3 #1875
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James Duffey
2010-01-16 17:28:46 UTC
Permalink
Dave - If an antenna suddenly changes its behavior, the cause is usually a broken connection somewhere, or a problem with the feedline, either shorted or open. So check these all first. It is easy for there to be a break in the ladder line, particularly if it uses a solid conductor that is hard to detect. Use an ohm metro from one end to the other. You should also look at the antenna with and without the balun (1:1) position) in place, the tuning shouldn't change a whole lot. If it does, look at the balun construction for a poor connection or bad solder joint. An antenna analyzer is a big help here, if you don't have one, I am sure that you can borrow one if you ask at a club meeting or speak up on the local repeater.

Having said that, if everything is in good shape, the first thing I suggest that you do is to model the antennas and transmission line and see what impedances you can expect to see where. This will help you understand what to do to match the antenna or where there are problems. Otherwise you are pretty much flying blind.

Get a good antenna modeling program, something like EZNEC, even the trial demo version will work for your case:

< http://www.eznec.com/ >

MMANA will work too and is free:

< http://www.smeter.net/antennas/mmana.php >

Model your antenna. You should see a reasonably low impedance on 80M, a high impedance on 40M, a moderate impedance on 30M, a high impedance on 20M, and well you should really do the modeling to get precise values. You will probably see a lot of loss on 80M as the antenna appears to be less than 0.1 wavelengths high. Anyway, record these values on the different bands.

The 16 ft of ladder line acts as a transformer to transform the impedance. You can calculate what the transformation will be with transmission line program; TLW is included with the Antenna Book and is good; W9CF has a nice java based app on the web:

< http://fermi.la.asu.edu/w9cf/tran/ >

which you can also download and run locally. It is nice as it runs on any machine that runs Java. You can also see how to do the transformations by hand in the Antenna Book.

Now, enter the antenna impedance values into the transmission line program and see where they get transformed. You will need to do this twice, once for the antenna - ladder line - coax run and once for the balun - coax - tuner run. Use the balun at 1:1 for the time being. You should try to borrow an antenna analyzer to verify your calculations, although with the high impedances the analyzer may not give too useful results.

None of these will be exact, but they should be in the ball park and give you an idea of what you should be doing to get a match.

This procedure will tell you what impedance you are expecting the tuners to tune. My guess is that it is within the range of your tuners and that you have a problem elsewhere, but do the math. If the impedance is outside the range you are expecting to tune, then you can change antenna or transmission line lengths until you get a match that is acceptable. That is far better than cutting and adding line and antenna lengths without an idea of what to expect.

The 16 ft of ladder line will have different effects on different bands. On 80M the electrical length of the transmission line will be small and you won't see much transformation. It is pretty much equivalent to lengthening the antenna. You should still see a low to moderate impedance here that the tuner is capable of matching. On 40M you will see more effect, but I suspect that the impedance will still be very high, perhaps too high for the tuner to match. On 20M the line length is a quarter wave, which should transform the high antenna impedance to a low to moderate impedance which the tuner can match easily.

The K-2 is pretty portable so you could try hooking it up to the antenna at the various junctions and see what happens. You should be able to get a match on 20M at the end of the ladder line. Try it with and without the balun in the 1:1 position. If that doesn't work, I suspect that you have problem in the K2 tuner or SWR circuit. You should be able to get an acceptable match with or without the balun, it won't be the same, but it should be close. You may or may not get a match here on 40M with the 1:1 balun, but you should get one with the 4:1 balun.

While the first thing I Would do is look for shorts or opens or bad connections in the system, you should probably read the Antenna Book chapter on transmission lines to get a feel for what is happening to the impedance at the various transmission line junctions.

Having encouraged you to measure and model, my gut feel is that you should be able to match this system with the K2 tuner and the 4:1 balun on all bands above 80M. I suspect that you have a problem in the antenna feedline and connections somewhere.

Let us know how this all works out and if you have further questions, feel free to ask. - Duffey
--
KK6MC
James Duffey
Cedar Crest NM
djmd
2010-01-16 22:05:18 UTC
Permalink
Hi James,

Thanks so much for the extremely informative reply! I will dig deep into a
lot of your suggestions later tonight. I think I may have overcomplicated
the issue, so let me see if I can give it a shakedown.

First off, lets forget everything besides 40m. That's really the band I am
concerned with first and foremost.

Before Elecraft came into my life, I was using a Yaesu FT840 with an MFJ941E
tuner. Coax (10' or so) out of the tuner, through the floor, into a barrel
that goes through cementboard to the outside. From there, short coax up to a
W2DU 4:1 current balun. Then 16' or so of windowline, and the dipole up
about 20', about 67' long. I have a very restricted yard for antennas and
just wanted to get on the air.

Anyway, after some poking and prodding I was able to consistently tune up on
40m fairly well, 1.5 or less. I made several CW contacts across the country
as well as Canada and South America.

Then I built the KX1 with the autotuner, and was not able to get under 5:1
from the same point with all the same components in place. No big deal, I
didn't intend on using the KX1 in the 'shack' anyway. But then I built the
K2/KAT2, and was getting pretty much the same result. As it stands right
now, I cannot break below 9.9:1 on the KAT2 on 40m from the shack. I've
tried different coax types and lengths on each side of the barrel and have
seen no improvement. Also, it doesn't matter which balun I use, or whether I
select 1:1 or 4:1 on the BL2. Results are the same.

Now, when I attach the K2 directly to the balun (now an Elecraft BL2) I can
get a great match on 40m. As I can add a very short piece between the K2 and
the balun with no ill effect, but once the coax is longer than about 5', the
SWR shoots up.

I picked up an analyzer today (259B). It's my first one, and I hardly know
what I'm doing, but I can tell you right off the bat that whether I attach
it to the coax in the shack, or directly to the balun, it's appearing to be
resonant at the same 3 places. Around 10mhz, 20mhz, and 26mhz. If there is
any other information you would like to know from the analyzer at any
specific frequency and connnection point, please let me know.

I hope this helps... I sincerely appreciate everyone's assistance. I'm still
learning and it's nice to have a place to get good info and not made to feel
like I'm an idiot.
:drunk::confused:
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Mike WA8BXN
1970-01-01 00:00:00 UTC
Permalink
It sounds like you have a broken/shorted wire somewhere. For testing, could
You run coax all the way to the antenna and see how that does? If you
Antenna is insulated wire, don't overlook the possibility of a break in the
Antenna itself. With 67 feet of wire, you should get a fairly decent match
Don Wilhelm
2010-01-16 22:45:20 UTC
Permalink
Dave,

No, you are not an idiot, nor drunk, but you may be confused by the
impedance transformation effects of a feedline.
I suggest you take a look at the ARRL Handbook or Antenna Book chapter
on Transmission Lines, especially the sections dealing with transmission
line matching sections if you want an understanding of what is going on.

The most common feedline matching section used by radio amateurs is the
quarter wavelength section - that one is relatively easy to understand
and the math is not complex. The underlying mechanism is that a low
impedance at one end will transform to a high impedance at the other
end. For example, if a 50 ohm electrical quarter wave of coax is used
and one end is connected to a 100 ohm load, the other end will have the
equivalent of a 25 ohm load - and if the far end of that same coax is
shorted, it will have a very high impedance (theoretically infinity, but
practically >4000 ohms) at the near end

Any length of feedline (and any impedance feedline) that is not matched
in its characteristic impedance at the load will act as an impedance
transformer.

It is nice to know the resonance points for your antenna system, but
what is really needed is the impedance (both resistive and reactive) at
the desired frequencies of operation. If we knew all your feedline
parameters (type, velocity factor, precise length, etc) we could likely
compute the impedance at any other frequency, but it is easier to just
measure it since your MFJ259 provides you with a tool to do exactly that.

There is no impedance transformation on a transmission line (of any
length) at the points where the antenna is matched to that line - that
is the situation at your "resonance" points if you only looked at the
SWR to determine resonance. The actual resonance point of the antenna
*system* is where the reactance goes to zero (or very low as indicated
on the MFJ259) - then at the resonance points you would look at the
resistive component - it is not likely to be 50 ohms.

One other piece of information that may help your 40 meter situation is
based on the fact that you can use the tuner successfully at the balun
location - and that is that an electrical half wavelength of
transmission line will repeat the impedance at each end - so if you
connect a total of a half wavelength transmission line between the
tuner and the balun, the tuner will tune it. A 40 meter electrical half
wave of solid dielectric coax will be in the vicinity of 42 feet
(VF+0.66, and the length of the foam dielectric coax will be close to
55.5 feet (VF+0.84). The lengths you have been trying are closer to a
quarter wavelength.

73,
Don W3FPR
Post by djmd
I picked up an analyzer today (259B). It's my first one, and I hardly know
what I'm doing, but I can tell you right off the bat that whether I attach
it to the coax in the shack, or directly to the balun, it's appearing to be
resonant at the same 3 places. Around 10mhz, 20mhz, and 26mhz. If there is
any other information you would like to know from the analyzer at any
specific frequency and connnection point, please let me know.
I hope this helps... I sincerely appreciate everyone's assistance. I'm still
learning and it's nice to have a place to get good info and not made to feel
like I'm an idiot.
djmd
2010-01-16 23:50:58 UTC
Permalink
Funny you should bring that up, Don. Last night at about 10pm I found myself
sitting on the couch with the '09 Handbook on my lap, opened up to page
21-1. I didn't get to 21.2, as the TV kinda took over my brain...

Definitely time to hit the books.

73 all!
Post by Don Wilhelm
Dave,
No, you are not an idiot, nor drunk, but you may be confused by the
impedance transformation effects of a feedline.
I suggest you take a look at the ARRL Handbook or Antenna Book chapter
on Transmission Lines, especially the sections dealing with transmission
line matching sections if you want an understanding of what is going on.
--
View this message in context: http://n2.nabble.com/High-SWR-on-20-and-40-tp4403006p4406363.html
Sent from the [OT] mailing list archive at Nabble.com.
Wes Stewart
2010-01-16 23:20:34 UTC
Permalink
If you are really interested in 40M only, why on earth don't you simplify your life and get rid of the tuners, the ladderline and the BL2. Run coax from the antenna spigot on the radio to the antenna. Coil up a few turns of it at the feed point if you insist on a balun (I don't necessarily), trim the length of the wire for minimum SWR at your frequency of interest and get on and operate.

Wes N7WS
From: djmd <djmd at fuse.net>
Subject: Re: [Elecraft] [OT] High SWR on 20 and 40
To: elecraft at mailman.qth.net
Date: Saturday, January 16, 2010, 3:05 PM
Hi James,
Thanks so much for the extremely informative reply! I will
dig deep into a
lot of your suggestions later tonight. I think I may have
overcomplicated
the issue, so let me see if I can give it a shakedown.
First off, lets forget everything besides 40m. That's
really the band I am
concerned with first and foremost.
Before Elecraft came into my life, I was using a Yaesu
FT840 with an MFJ941E
tuner. Coax (10' or so) out of the tuner, through the
floor, into a barrel
that goes through cementboard to the outside. From there,
short coax up to a
W2DU 4:1 current balun. Then 16' or so of windowline, and
the dipole up
about 20', about 67' long. I have a very restricted yard
for antennas and
just wanted to get on the air.
Anyway, after some poking and prodding I was able to
consistently tune up on
40m fairly well, 1.5 or less. I made several CW contacts
across the country
as well as Canada and South America.
Then I built the KX1 with the autotuner, and was not able
to get under 5:1
from the same point with all the same components in place.
No big deal, I
didn't intend on using the KX1 in the 'shack' anyway. But
then I built the
K2/KAT2, and was getting pretty much the same result. As it
stands right
now, I cannot break below 9.9:1 on the KAT2 on 40m from the
shack. I've
tried different coax types and lengths on each side of the
barrel and have
seen no improvement. Also, it doesn't matter which balun I
use, or whether I
select 1:1 or 4:1 on the BL2. Results are the same.
Now, when I attach the K2 directly to the balun (now an
Elecraft BL2) I can
get a great match on 40m. As I can add a very short piece
between the K2 and
the balun with no ill effect, but once the coax is longer
than about 5', the
SWR shoots up.
I picked up an analyzer today (259B). It's my first one,
and I hardly know
what I'm doing, but I can tell you right off the bat that
whether I attach
it to the coax in the shack, or directly to the balun, it's
appearing to be
resonant at the same 3 places. Around 10mhz, 20mhz, and
26mhz. If there is
any other information you would like to know from the
analyzer at any
specific frequency and connnection point, please let me
know.
I hope this helps... I sincerely appreciate everyone's
assistance. I'm still
learning and it's nice to have a place to get good info and
not made to feel
like I'm an idiot.
--
View this message in context: http://n2.nabble.com/High-SWR-on-20-and-40-tp4403006p4406096.html
Sent from the [OT] mailing list archive at Nabble.com.
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dw
2010-01-17 06:20:17 UTC
Permalink
I have done this in the past to deal with ladder line length on multi
band use.
cut the following lengths of ladder line.

1 foot
2 foot
4 foot
8 foot

Solder alligator clips on all ends

By using these in combinations, you now have the ability to increase
your line length from 1-15 feet.
Test SWR on the offending bands while adding increments of 1 foot at a
time.
The fact that you are finding the high SWR on both 20 and 40 could
indicate a high impedance point at the input end in 1/4 wave increments.
15' will be an even 1/8 wave on 40 and an even 1/4 wave on 20.
Adding some length of line might push this away from the input end on
both bands.

I will guess that 6' or 9' will be a good numbers to add.

Duane
--
Bw_dw at fastmail.net
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