balun at resonance?
 

hi

i've build a 80 center fed dipole, cut for 80, to use multiband-- fed
via coax.

my goal is to use a balun.

my recomendations so far have been for 1:1 /4:1 and 9:1, got nearly a
equal tally of votes on each



leaves me a bit confused however

lets say i use a 9:1 for example

on 80 my dipole is resonant, therefore should be around 72ohms. lets
presume it is

now w/a 9:1 attached what happens? is this my trade off, ie i become
very ineff at resonance while gaining some better match at the non
resonant points?


thanks

m

Too bad you couldn't use 300 ohm ladder line instead of coax. With the
addition of a antenna tuner and ladder line, you could eliminate the use
of the balun altogether and mathcing would not be a problem on any band
(well almost).

John

KE0GG

ml wrote:
hi

i've build a 80 center fed dipole, cut for 80, to use multiband-- fed
via coax.

my goal is to use a balun.

my recomendations so far have been for 1:1 /4:1 and 9:1, got nearly a
equal tally of votes on each



leaves me a bit confused however

lets say i use a 9:1 for example

on 80 my dipole is resonant, therefore should be around 72ohms. lets
presume it is

now w/a 9:1 attached what happens? is this my trade off, ie i become
very ineff at resonance while gaining some better match at the non
resonant points?


thanks

m

ml wrote:
i've build a 80 center fed dipole, cut for 80, to use multiband--
fed via coax.

It is not a good idea to use a coax-fed 80m CFD on the other bands
because of losses due to SWR in the coax. Your balun problems are the
least of your worries. If you feed the 80m CFD with ladder-line, you
could use it on the other bands without suffering massive SWR losses.
For that configuration, all one needs is a 1:1 choke at the tuner. Take
a look at http://www.qsl.net/w5dxp/notuner.htm for some ideas on your
antenna.
--
73, Cecil, W5DXP

On Mon, 03 Jan 2005 11:37:25 GMT, ml wrote:

hi

i've build a 80 center fed dipole, cut for 80, to use multiband-- fed
via coax.

my goal is to use a balun.

my recomendations so far have been for 1:1 /4:1 and 9:1, got nearly a
equal tally of votes on each



leaves me a bit confused however

lets say i use a 9:1 for example

on 80 my dipole is resonant, therefore should be around 72ohms. lets
presume it is

now w/a 9:1 attached what happens? is this my trade off, ie i become
very ineff at resonance while gaining some better match at the non
resonant points?

Permit me to ask a simple question. Aside from the transformation of
the impedance, what benefit were you planning to obtain from the
Balun? If you can't answer that question, then perhaps you don't
really need a Balun.

Another question, if you don't mind. Are you familiar with Choke
Baluns or the W2DU Balun?

Bob, W9DMK, Dahlgren, VA
http://www.qsl.net/w9dmk

Permit me to ask a simple question. Aside from the transformation of
the impedance, what benefit were you planning to obtain from the
Balun? If you can't answer that question, then perhaps you don't
really need a Balun.

One would think that converting from a balanced antenna to unbalanced
feedline would be a primary benefit offered by a balun.

On Mon, 3 Jan 2005 10:36:31 -0500, "Dave VanHorn"
wrote:

Permit me to ask a simple question. Aside from the transformation of
the impedance, what benefit were you planning to obtain from the
Balun? If you can't answer that question, then perhaps you don't
really need a Balun.

One would think that converting from a balanced antenna to unbalanced
feedline would be a primary benefit offered by a balun.

I'm perfectly aware of most of the reasons for using a balun. I'm
trying to uncover the motivation of the complainant.


Bob, W9DMK, Dahlgren, VA
http://www.qsl.net/w9dmk

Very clever design, Robert! Your system should provide gain at the
higher operationg frquencies as a bonus.

John

KE0GG

W9DMK (Robert Lay) wrote:
On Mon, 3 Jan 2005 10:36:31 -0500, "Dave VanHorn"
wrote:


Permit me to ask a simple question. Aside from the transformation of
the impedance, what benefit were you planning to obtain from the
Balun? If you can't answer that question, then perhaps you don't
really need a Balun.

One would think that converting from a balanced antenna to unbalanced
feedline would be a primary benefit offered by a balun.


I'm perfectly aware of most of the reasons for using a balun. I'm
trying to uncover the motivation of the complainant.


Bob, W9DMK, Dahlgren, VA
http://www.qsl.net/w9dmk

Sorry, I meant this reply to Cecil, W5DXP.

John

John Steffes wrote:
Very clever design, Robert! Your system should provide gain at the
higher operationg frquencies as a bonus.

John

KE0GG

W9DMK (Robert Lay) wrote:

On Mon, 3 Jan 2005 10:36:31 -0500, "Dave VanHorn"
wrote:


Permit me to ask a simple question. Aside from the transformation of
the impedance, what benefit were you planning to obtain from the
Balun? If you can't answer that question, then perhaps you don't
really need a Balun.


One would think that converting from a balanced antenna to unbalanced
feedline would be a primary benefit offered by a balun.



I'm perfectly aware of most of the reasons for using a balun. I'm
trying to uncover the motivation of the complainant.


Bob, W9DMK, Dahlgren, VA
http://www.qsl.net/w9dmk

thank you for responding,

well, chaning the impedance, you mentioned i thought would be important,
as also i'd like to not have my 'shield' flowing w/rf

i've been told it might help reduce 'interference' not sure

however i fail to see how my ability or inablity to explain something
equates to 'needing' a particular part or not, hence why i want to
learn if i knew, all the ''angles' and aspects i wouldn't post

i am still missing the info i seek



In article ,
(Robert Lay) wrote:

On Mon, 03 Jan 2005 11:37:25 GMT, ml wrote:

hi

i've build a 80 center fed dipole, cut for 80, to use multiband-- fed
via coax.

my goal is to use a balun.

my recomendations so far have been for 1:1 /4:1 and 9:1, got nearly a
equal tally of votes on each



leaves me a bit confused however

lets say i use a 9:1 for example

on 80 my dipole is resonant, therefore should be around 72ohms. lets
presume it is

now w/a 9:1 attached what happens? is this my trade off, ie i become
very ineff at resonance while gaining some better match at the non
resonant points?

Permit me to ask a simple question. Aside from the transformation of
the impedance, what benefit were you planning to obtain from the
Balun? If you can't answer that question, then perhaps you don't
really need a Balun.

Another question, if you don't mind. Are you familiar with Choke
Baluns or the W2DU Balun?

Bob, W9DMK, Dahlgren, VA
http://www.qsl.net/w9dmk

On Tue, 04 Jan 2005 03:01:36 GMT, ml wrote:



thank you for responding,

well, chaning the impedance, you mentioned i thought would be important,
as also i'd like to not have my 'shield' flowing w/rf

That is exactly why I asked. Since you do not want RF on the outer
shield, then instead of a transformer type balun, you may find that
the choke balun or W2DU balun will better serve your needs. It is
designed specifically to reduce the flow of RF on the outer shield.

i've been told it might help reduce 'interference' not sure

Correct!

however i fail to see how my ability or inablity to explain something
equates to 'needing' a particular part or not, hence why i want to
learn if i knew, all the ''angles' and aspects i wouldn't post

i am still missing the info i seek

You were apparently disturbed by my question. However, it has been my
experience that it is very important to find out what is the real
problem, because it is only when you know the real problem you can
hope to find the best answer.

For example, someone asks for a recommendation for a good hammer, and
he gets hundreds of recommendations for good hammers - all different
and all good hammers for something, but none are the best answer for
his needs. Once it is discovered that what he really needs is a good
way to kill chickens - then we tell him to wring their necks.

Do you see my point?

It is truly a shame, but most people do not know how to seek help,
properly. They must forget their idea of a solution and define their
real problem. It is not a natural talent, but is certainly a valuable
one, which earns them better answers, quicker.

Bob, W9DMK, Dahlgren, VA
http://www.qsl.net/w9dmk

my recomendations so far have been for 1:1 /4:1 and 9:1, got nearly a
equal tally of votes on each

leaves me a bit confused however

==================================

Dear m, Confusion is only to be expected.

Its sometimes a good idea to take the average of the recommendations offered
in this newsgroup.

But in your case you should include in the offerings a 0-to-0 balun - ie.,
no balun ar all.

So the most logical thing to begin with is NO balun (because it is the least
expensive) which in all likelihood will probably do fine on 80 meters using
a coax feedline.

But, having an experimental mind, after that you could try an indeteminate
impedance-to-indeterminate impedance choke balun. The sort wound with twin
speaker cable on a ferrite ring. Which in some circumstances MIGHT work
slightly better by doing what a balun is supposed to do but will certainly
not make things worse.

And whatever you use, a tuner will be essential for multi-band operation.
Length of dipole is non-critical, whatever fits into your backyard. Prefer
450-ohm or open-wire transmission line for the best performing HF dipole
antenna you will ever have. Unless you can make it even higher.

Happy experimenting in 2005 !
----
Reg, G4FGQ

In article ,
"Reg Edwards" wrote:

my recomendations so far have been for 1:1 /4:1 and 9:1, got nearly a
equal tally of votes on each

leaves me a bit confused however

==================================

Dear m, Confusion is only to be expected.

Its sometimes a good idea to take the average of the recommendations offered
in this newsgroup.

But in your case you should include in the offerings a 0-to-0 balun - ie.,
no balun ar all.
i did post this option,



So the most logical thing to begin with is NO balun (because it is the least
expensive) which in all likelihood will probably do fine on 80 meters using
a coax feedline.
well the entire point is that it's for multiband use, so id be very
clear if it was just one resonant band but it's multiband hand my
desire for a balun to even things out some :)




But, having an experimental mind, after that you could try an indeteminate
impedance-to-indeterminate impedance choke balun. The sort wound with twin
speaker cable on a ferrite ring. Which in some circumstances MIGHT work
slightly better by doing what a balun is supposed to do but will certainly
not make things worse.

And whatever you use, a tuner will be essential for multi-band operation.
Length of dipole is non-critical, whatever fits into your backyard. Prefer
450-ohm or open-wire transmission line for the best performing HF dipole
antenna you will ever have. Unless you can make it even higher.

Happy experimenting in 2005 !
----
Reg, G4FGQ

On Tue, 4 Jan 2005 17:51:15 +0000 (UTC), "Reg Edwards"
wrote:

Just to add to the fray, here is my recent experience. My antenna is
a 200 foot dipole (flatop) at 45 feet center fed with about 50 feet of
450 ohm ladder line down to a balun then 20 feet of 72 ohm coax into a
homebrew L match tuner. It tunes 160 thru 10 meters and works very
well on all bands. I tried different balun configurations with varied
results. Settled on a 4:1 powdered iron (red) core 2 inch toroid of 8
bifilar turns number 12 wire, the center tap connected to the coax
shield and also to a separate ground rod 2 inches below the balun.
Good results on the air and no RFI in the shack. A 1:1 balun on the
same core tuned up OK, worked on the air OK but produced RFI. A
coiled up coax choke balun gave bad RFI into phone, sterio and TV.
Tried 6 mix43 ferrite sleves on the coax up near the ladder line with
no balun, this was worst of all grounded or ungrounded, producing
severe RFI, in fact the 600 watt linear was unusable on 80 meters due
to RF into the rig. So they all worked, but the 4:1 grounded balun is
best by far in my situation. Now if I was to put a half twist in the
ladder line and take up religion, that could all change.
73s VE3ELQ

my recomendations so far have been for 1:1 /4:1 and 9:1, got nearly a
equal tally of votes on each

leaves me a bit confused however

==================================

Dear m, Confusion is only to be expected.

Its sometimes a good idea to take the average of the recommendations offered
in this newsgroup.

But in your case you should include in the offerings a 0-to-0 balun - ie.,
no balun ar all.

So the most logical thing to begin with is NO balun (because it is the least
expensive) which in all likelihood will probably do fine on 80 meters using
a coax feedline.

But, having an experimental mind, after that you could try an indeteminate
impedance-to-indeterminate impedance choke balun. The sort wound with twin
speaker cable on a ferrite ring. Which in some circumstances MIGHT work
slightly better by doing what a balun is supposed to do but will certainly
not make things worse.

And whatever you use, a tuner will be essential for multi-band operation.
Length of dipole is non-critical, whatever fits into your backyard. Prefer
450-ohm or open-wire transmission line for the best performing HF dipole
antenna you will ever have. Unless you can make it even higher.

Happy experimenting in 2005 !
----
Reg, G4FGQ