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Horizontal loop - balun or no balun ?



 
 
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  #1  
Old December 13th 03, 09:49 AM
Per Enocson
Guest
 
Posts: n/a
Default Horizontal loop - balun or no balun ?

My 165 m horizontal loop, which is up about 14 meters and has sort of
rhombic shape, is a great antenna, also for DX.

Currently, I feed it at a corner with a length of ( approx 12 m) 50 ohm RG
58 coax and enjoy a good SWR at my tx end (1:2 or less) on 160, 17 and 10
m. On other bands, SWR is much higher, which is easily fixed with my
automatic ATU (Elecraft KAT 100). I realize I may have some losses on these
bands, but try to comfort myself with the fact that the coax feed is quite
short.

I now plan to go QRO, using a PA delivering 5-600 watts. I have a good old
Heathkit SA 2060 tuner, capable of a kw, with either unbalanced or balanced
(4:1 voltage balun) outputs.Here are a couple of the questions I am asking
myself:

1. Should I stick to coax feed or switch to ladder line? (reduce losses,
secure power handling capability)?

2. If I switch to ladder line, I prefer no taking it into the schack (afraid
of RFI and computer problems, also unpractical). How should I arrange
switching from ladder line to coax outside the schack window, to minimize
losses and "play it safe" when it comes to the balun specification. What
type of balun and what ratio should it have (1:1 better than 4:1)? Which
particular baluns/suppliers do you suggest?

3. Or, at the end of the day, would I be better off, from a loss point of
view, with sticking to coax while upgrading the coax to higher power
handling capability(I have some nice, thick RG 11 lying around here, it is
75 ohms though). The "loop skywire" in the ARRL Antenna Book advices us to
avoid baluns.....

I realize that there is no simple answer to these questions, and am very
grateful for any advice from the group.

Thank you and happy holidays!

Per SM0WRA


  #2  
Old December 13th 03, 11:37 AM
KC1DI
Guest
 
Posts: n/a
Default

On Sat, 13 Dec 2003 09:49:51 GMT, "Per Enocson"
wrote:

My 165 m horizontal loop, which is up about 14 meters and has sort of
rhombic shape, is a great antenna, also for DX.

Currently, I feed it at a corner with a length of ( approx 12 m) 50 ohm RG
58 coax and enjoy a good SWR at my tx end (1:2 or less) on 160, 17 and 10
m. On other bands, SWR is much higher, which is easily fixed with my
automatic ATU (Elecraft KAT 100). I realize I may have some losses on these
bands, but try to comfort myself with the fact that the coax feed is quite
short.

I now plan to go QRO, using a PA delivering 5-600 watts. I have a good old
Heathkit SA 2060 tuner, capable of a kw, with either unbalanced or balanced
(4:1 voltage balun) outputs.Here are a couple of the questions I am asking
myself:

1. Should I stick to coax feed or switch to ladder line? (reduce losses,
secure power handling capability)?

2. If I switch to ladder line, I prefer no taking it into the schack (afraid
of RFI and computer problems, also unpractical). How should I arrange
switching from ladder line to coax outside the schack window, to minimize
losses and "play it safe" when it comes to the balun specification. What
type of balun and what ratio should it have (1:1 better than 4:1)? Which
particular baluns/suppliers do you suggest?

3. Or, at the end of the day, would I be better off, from a loss point of
view, with sticking to coax while upgrading the coax to higher power
handling capability(I have some nice, thick RG 11 lying around here, it is
75 ohms though). The "loop skywire" in the ARRL Antenna Book advices us to
avoid baluns.....

I realize that there is no simple answer to these questions, and am very
grateful for any advice from the group.

Thank you and happy holidays!

Per SM0WRA


I also use a 160 m loop that this up 10 m here much the same as
yours.. I feed mine with 75 ohm coax to a 1:1 Choke balun just out
side the shack maybe 10 feet of coax then balanced line the rest of
the way it works great for me. I've in the past fed it with open wire
all the way to the tuner in the shack. But as you mentioned if gave
me troubles with unwanted RFI pickup from computer monitors ETC. I've
also fed it all the way with Coax (75 ohm] and that worked quite well
except on 12 & 10 meters .. So I guess what I'm saying is if the Coax
run is fairly short say 20 feet or so you won't notice a big
difference except maybe on 12 and 10 meters while feeding it with open
wire or coax.. The big loops just seem to work great. Good luck with
yours and all the best for the holidays.
73 Dave KC1DI



  #3  
Old December 13th 03, 01:29 PM
K9SQG
Guest
 
Posts: n/a
Default

I use window line to feed my horizontal loop and have found that it can be fed
into the shack quite easily. Next year I'm going to try true open wire line
and see how it works out.

As to RFI in the shack, I have none. Generally, with a loop, the currents in
the open wire line will be of equal amplitude but of opposite phase; hence no
radiation. While I don't have a computer, I do use a Macintosh which does
everything a computer does only easier, and it has had no problems running
while I'm using legal limit power through the feedline which is only two feet
from the Macintosh.

In terms of recommeded priority, I'd say use open wire line or window line to
feed the loop, second best would be to use a balun at the antenna, and third
would be to use a remote tuner where the feedline enters the home, and finally
a remote tuner at the antenna feedpoint.

But you have to decide for yourself what is important to you in terms of
performance, cost, convenience, appearance, etc.

Best of luck and 73s,

Evan
  #4  
Old December 13th 03, 09:05 PM
Per Enocson
Guest
 
Posts: n/a
Default

Thank you Evan! I guess I should give the balanced line a try before
counting it out. What kind of antenna tuner do you use and how do you
connect your balanced line to it? Through a balun or not?

73´s de Per SM0WRA



"K9SQG" skrev i meddelandet
...
I use window line to feed my horizontal loop and have found that it can be

fed
into the shack quite easily. Next year I'm going to try true open wire

line
and see how it works out.

As to RFI in the shack, I have none. Generally, with a loop, the currents

in
the open wire line will be of equal amplitude but of opposite phase; hence

no
radiation. While I don't have a computer, I do use a Macintosh which does
everything a computer does only easier, and it has had no problems running
while I'm using legal limit power through the feedline which is only two

feet
from the Macintosh.

In terms of recommeded priority, I'd say use open wire line or window line

to
feed the loop, second best would be to use a balun at the antenna, and

third
would be to use a remote tuner where the feedline enters the home, and

finally
a remote tuner at the antenna feedpoint.

But you have to decide for yourself what is important to you in terms of
performance, cost, convenience, appearance, etc.

Best of luck and 73s,

Evan



  #5  
Old December 13th 03, 09:09 PM
Per Enocson
Guest
 
Posts: n/a
Default

Dave,

Excellent help for me. I will try both ways (experimenting is a fun part of
our hobby). Could you describe your 1:1 current choke balun to me?

Thanks, 73 de Per SM0WRA
"KC1DI" skrev i meddelandet
news
On Sat, 13 Dec 2003 09:49:51 GMT, "Per Enocson"
wrote:

My 165 m horizontal loop, which is up about 14 meters and has sort of
rhombic shape, is a great antenna, also for DX.

Currently, I feed it at a corner with a length of ( approx 12 m) 50 ohm

RG
58 coax and enjoy a good SWR at my tx end (1:2 or less) on 160, 17 and

10
m. On other bands, SWR is much higher, which is easily fixed with my
automatic ATU (Elecraft KAT 100). I realize I may have some losses on

these
bands, but try to comfort myself with the fact that the coax feed is

quite
short.

I now plan to go QRO, using a PA delivering 5-600 watts. I have a good

old
Heathkit SA 2060 tuner, capable of a kw, with either unbalanced or

balanced
(4:1 voltage balun) outputs.Here are a couple of the questions I am

asking
myself:

1. Should I stick to coax feed or switch to ladder line? (reduce losses,
secure power handling capability)?

2. If I switch to ladder line, I prefer no taking it into the schack

(afraid
of RFI and computer problems, also unpractical). How should I arrange
switching from ladder line to coax outside the schack window, to minimize
losses and "play it safe" when it comes to the balun specification. What
type of balun and what ratio should it have (1:1 better than 4:1)? Which
particular baluns/suppliers do you suggest?

3. Or, at the end of the day, would I be better off, from a loss point of
view, with sticking to coax while upgrading the coax to higher power
handling capability(I have some nice, thick RG 11 lying around here, it

is
75 ohms though). The "loop skywire" in the ARRL Antenna Book advices us

to
avoid baluns.....

I realize that there is no simple answer to these questions, and am very
grateful for any advice from the group.

Thank you and happy holidays!

Per SM0WRA


I also use a 160 m loop that this up 10 m here much the same as
yours.. I feed mine with 75 ohm coax to a 1:1 Choke balun just out
side the shack maybe 10 feet of coax then balanced line the rest of
the way it works great for me. I've in the past fed it with open wire
all the way to the tuner in the shack. But as you mentioned if gave
me troubles with unwanted RFI pickup from computer monitors ETC. I've
also fed it all the way with Coax (75 ohm] and that worked quite well
except on 12 & 10 meters .. So I guess what I'm saying is if the Coax
run is fairly short say 20 feet or so you won't notice a big
difference except maybe on 12 and 10 meters while feeding it with open
wire or coax.. The big loops just seem to work great. Good luck with
yours and all the best for the holidays.
73 Dave KC1DI





  #6  
Old December 14th 03, 01:28 AM
KC1DI
Guest
 
Posts: n/a
Default

It's a W2DU type. with beads slipped over the coax.
73 dave


On Sat, 13 Dec 2003 21:09:09 GMT, "Per Enocson"
wrote:

Dave,

Excellent help for me. I will try both ways (experimenting is a fun part of
our hobby). Could you describe your 1:1 current choke balun to me?

Thanks, 73 de Per SM0WRA
"KC1DI" skrev i meddelandet
news
On Sat, 13 Dec 2003 09:49:51 GMT, "Per Enocson"
wrote:

My 165 m horizontal loop, which is up about 14 meters and has sort of
rhombic shape, is a great antenna, also for DX.

Currently, I feed it at a corner with a length of ( approx 12 m) 50 ohm

RG
58 coax and enjoy a good SWR at my tx end (1:2 or less) on 160, 17 and

10
m. On other bands, SWR is much higher, which is easily fixed with my
automatic ATU (Elecraft KAT 100). I realize I may have some losses on

these
bands, but try to comfort myself with the fact that the coax feed is

quite
short.

I now plan to go QRO, using a PA delivering 5-600 watts. I have a good

old
Heathkit SA 2060 tuner, capable of a kw, with either unbalanced or

balanced
(4:1 voltage balun) outputs.Here are a couple of the questions I am

asking
myself:

1. Should I stick to coax feed or switch to ladder line? (reduce losses,
secure power handling capability)?

2. If I switch to ladder line, I prefer no taking it into the schack

(afraid
of RFI and computer problems, also unpractical). How should I arrange
switching from ladder line to coax outside the schack window, to minimize
losses and "play it safe" when it comes to the balun specification. What
type of balun and what ratio should it have (1:1 better than 4:1)? Which
particular baluns/suppliers do you suggest?

3. Or, at the end of the day, would I be better off, from a loss point of
view, with sticking to coax while upgrading the coax to higher power
handling capability(I have some nice, thick RG 11 lying around here, it

is
75 ohms though). The "loop skywire" in the ARRL Antenna Book advices us

to
avoid baluns.....

I realize that there is no simple answer to these questions, and am very
grateful for any advice from the group.

Thank you and happy holidays!

Per SM0WRA


I also use a 160 m loop that this up 10 m here much the same as
yours.. I feed mine with 75 ohm coax to a 1:1 Choke balun just out
side the shack maybe 10 feet of coax then balanced line the rest of
the way it works great for me. I've in the past fed it with open wire
all the way to the tuner in the shack. But as you mentioned if gave
me troubles with unwanted RFI pickup from computer monitors ETC. I've
also fed it all the way with Coax (75 ohm] and that worked quite well
except on 12 & 10 meters .. So I guess what I'm saying is if the Coax
run is fairly short say 20 feet or so you won't notice a big
difference except maybe on 12 and 10 meters while feeding it with open
wire or coax.. The big loops just seem to work great. Good luck with
yours and all the best for the holidays.
73 Dave KC1DI





 




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