4:1 balun question
 

Anyone here have a good web reference on making a 4:1 balun? I'm looking
for the dual core design, not the single core design. Lots of those to
google.

Do the single core designs really not work? I had a single core
homebrew that seemed to work, but I'm a tad confused after hearing that
they don't.

- 73 de Mike KB3EIA -

4:1 balun question
 

On Tue, 02 May 2006 22:58:00 -0400, Mike Coslo
wrote:

Anyone here have a good web reference on making a 4:1 balun? I'm looking
for the dual core design, not the single core design. Lots of those to
google.

Do the single core designs really not work? I had a single core
homebrew that seemed to work, but I'm a tad confused after hearing that
they don't.

The Sept/Oct 2005 issue of QEX has a 4:1 balun design that may
interest you. It can be found on the ARRL's members only web site.

http://www.arrl.org/qex/2005/qx9roos.pdf

73,
Danny, K6MHE

In my many years I have come to a conclusion that one
useless man is a shame, two is a law firm, and three
or more is a congress. - John Adams

email: k6mheatarrldotnet
http://www.k6mhe.com/

4:1 balun question
 

Dan Richardson wrote:
The Sept/Oct 2005 issue of QEX has a 4:1 balun design that may
interest you. It can be found on the ARRL's members only web site.

Would a 4:1 voltage balun fed through a husky 1:1 choke
(W2DU BALUN) accomplish the same thing?
--
73, Cecil http://www.qsl.net/w5dxp

4:1 balun question
 

Mike Coslo wrote:
Do the single core designs really not work? I had a single core
homebrew that seemed to work, but I'm a tad confused after hearing that
they don't.

The single core designs are usually voltage baluns and
what we hams want are balanced currents. I don't see
why you couldn't just add a husky 1:1 W2DU style choke
on the 50 ohm side of your 4:1 voltage balun to inhibit
common mode current. The extra toroid in the afore mentioned
QEX article is a 1:1 choke attached to a 4:1 voltage balun.
--
73, Cecil http://www.qsl.net/w5dxp

4:1 balun question
 

Single core baluns do work in the sense that they will pass signals
without strong attenuation in most cases, they will transform
impedances properly, and they are broadband. They will work well in a
system that is already fairly well balanced.

You will need to evaluate your application as single core 4:1 baluns
have the following disadvantages compared to, say, the 4:1 Guanella
two-core current balun:

1. They do not supress common-mode currents well.
2. They require a larger core to work with a given power in a fairly
well-balanced system (a severely unbalanced system might have to be
evaluated more carefully to determine core size).
3. When properly built with a core that couples most all flux to all
windings, the single core balun will have no output into a fully
unbalanced system. An unbalanced system is one where either end of the
load is grounded. A balanced system is one where the load is grounded
in the center. There is also a floating system where the load is not
grounded at all.

They have the advantage that they only use one core.

On an antenna, the effects of using a voltage balun (all single core
4:1 baluns seem to be voltage baluns) instead of a current balun can be
subtle or even undetectable. My experience with an offset fed dipole
was that the antenna receive signal-to-noise ratio degraded under some
conditions without a current balun in place (maybe simply because the
pattern was different). Adding the current balun helped, and the
antenna tuned a little more as I expected it to on the higher bands.
My feedline is near a huge aluminum siding slab, and I think there was
some effect from that.

An offset fed dipole can be pretty unbalanced, though. Other antennas
might do just fine with a single core balun.

I'm sure others will add their comments, and perhaps disagree with me.
This has been a controversial subject in the past, but more recent
discussions have been better.

73,
Glenn Dixon AC7ZN

4:1 balun question
 

Here is what seems to be a nice link for the Guanella 2 co
http://www.njqrp.org/balun/Balun%20M...0-%20final.pdf

4:1 balun question
 

I forgot to mention: using a voltage balun on an antenna can have
RF-in-the-shack implications. A 20M folded dipole I once built with a
4:1 trifilar wound voltage balun was terrible even though it was
center-fed. Tuning was extremely touchy and removing my hand from the
tuner knob would detune the antenna. I did not try a current balun on
that antenna and it is history now. Maybe some one else has had
simialr experience.

Glenn

4:1 balun question
 

I asked a similar question a bit ago. Here's one I got in response.

http://www.yccc.org/Articles/W1HIS/C...S2006Apr06.pdf

This guy made a MONSTER 4:1 current balun.

73,
Dan
N3OX

4:1 balun question
 

Mike Coslo wrote:
Anyone here have a good web reference on making a 4:1 balun? I'm looking
for the dual core design, not the single core design. Lots of those to
google.

Do the single core designs really not work? I had a single core
homebrew that seemed to work, but I'm a tad confused after hearing that
they don't.

- 73 de Mike KB3EIA -


Better, easier and probably cheaper to buy what you need from Buxcomm.com

4:1 balun question
 

The Buxcomm baluns seem to mention "THE core" when describing their 4:1
"current" baluns, and I've had plenty of my responses to my question of
whether or not you can wind a true 4:1 current balun on a single toroid
core.

The answer is no.

I'm sure if you go with the Buxcomm "BIG TALKER" "2500 watt" unit it
won't overheat. It won't ensure equal currents either.

On a marginally related note, why buy when you can build? Better,
easier, and probably cheaper?

Better? Nope, not a real current balun and good luck getting real
technical info out of many vendors.

Easier? Yeah, unless you have to spend months trying to figure out
why, even though you've got a "current" balun keeping the common mode
RF "off" of your feedline, you still get RF bites from your mic.

Probably cheaper? Very possibly true... it is often cheaper to buy an
assembled product than to buy the parts and put one together, but
that's just no fun!

I can't advocate the purchase of simple ham radio station accessories
when someone is trying to build them instead.

73,
Dan
N3OX

4:1 balun question
 

Dan Richardson wrote:
On Tue, 02 May 2006 22:58:00 -0400, Mike Coslo
wrote:


Anyone here have a good web reference on making a 4:1 balun? I'm looking
for the dual core design, not the single core design. Lots of those to
google.

Do the single core designs really not work? I had a single core
homebrew that seemed to work, but I'm a tad confused after hearing that
they don't.


The Sept/Oct 2005 issue of QEX has a 4:1 balun design that may
interest you. It can be found on the ARRL's members only web site.

http://www.arrl.org/qex/2005/qx9roos.pdf


Thanks, Dan, I'm reading it now...

- 73 de Mike KB3EIA -

4:1 balun question
 

Cecil Moore wrote:
Mike Coslo wrote:

Do the single core designs really not work? I had a single core
homebrew that seemed to work, but I'm a tad confused after hearing
that they don't.


The single core designs are usually voltage baluns and
what we hams want are balanced currents. I don't see
why you couldn't just add a husky 1:1 W2DU style choke
on the 50 ohm side of your 4:1 voltage balun to inhibit
common mode current. The extra toroid in the afore mentioned
QEX article is a 1:1 choke attached to a 4:1 voltage balun.


I think you are right, Cecil. I'm digesting the pdf now. Probably take
a few reads tho' it's been a long, long day....

- 73 de Mike KB3EIA -

4:1 balun question
 

wrote:
Here is what seems to be a nice link for the Guanella 2 co
http://www.njqrp.org/balun/Balun%20M...0-%20final.pdf

Aha! I knew there was one out there somewhere!

- 73 de Mike KB3EIA -

4:1 balun question
 

Butch Magee wrote:
Mike Coslo wrote:

Anyone here have a good web reference on making a 4:1 balun? I'm
looking for the dual core design, not the single core design. Lots of
those to google.

Do the single core designs really not work? I had a single core
homebrew that seemed to work, but I'm a tad confused after hearing
that they don't.

- 73 de Mike KB3EIA -



Better, easier and probably cheaper to buy what you need from Buxcomm.com


I think you're right, Butch, but I *really* love making my own stuff. 8^)

- 73 de Mike KB3EIA -

4:1 balun question
 

On Wed, 03 May 2006 13:22:45 GMT, Cecil Moore
wrote:

The single core designs are usually voltage baluns and
what we hams want are balanced currents. I don't see
why you couldn't just add a husky 1:1 W2DU style choke
on the 50 ohm side of your 4:1 voltage balun to inhibit
common mode current. The extra toroid in the afore mentioned
QEX article is a 1:1 choke attached to a 4:1 voltage balun.

Did you read the article Cecil? He place the current balun/choke on
the opposite side. Looked like an interesting approach.

Danny

In my many years I have come to a conclusion that one
useless man is a shame, two is a law firm, and three
or more is a congress. - John Adams

email: k6mheatarrldotnet
http://www.k6mhe.com/

4:1 balun question
 

Dan Richardson wrote:
Did you read the article Cecil? He place the current balun/choke on
the opposite side. Looked like an interesting approach.

Yes, I'm wondering if things would change if the positions
were reversed? How does that choke perform when it sees
2000 + j1000 ohms?
--
73, Cecil http://www.qsl.net/w5dxp

4:1 balun question
 

When it sees 2000 + j1000 ohms there's hardly any current to choke
anyway.

4:1 balun question
 

"Reg Edwards" wrote:
When it sees 2000 + j1000 ohms there's hardly any current to choke
anyway.

Yes, but how much current is there 3/8WL back from that point?
--
73, Cecil, W5DXP

4:1 balun question
 

"Cecil Moore" wrote in message
om...

"Reg Edwards" wrote:
When it sees 2000 + j1000 ohms there's hardly any current to choke
anyway.

Yes, but how much current is there 3/8WL back from that point?
--
73, Cecil, W5DXP

Isn't that where you should be placing the choke? Give it some work
to do! Don't blame the choke for doing nothing. Blame yourself!
----
Reg.

4:1 balun question
 

"Reg Edwards" wrote:

W5DXP wrote:
Yes, but how much current is there 3/8WL back from that point?

Isn't that where you should be placing the choke?

Kinda hard to do if the feedline is ladder-line. Maybe a more
logical thing to do is to increase the length of the ladder-line until
a current maximum point is available at the coax/ladder-line
junction.
--
73, Cecil, W5DXP

4:1 balun question
 

Please all, remember,

The common-mode currents the choke is suppressing are not necessarily
related to the antenna impedance (the load) or the transmit/receive
currents flowing in the antenna, though there can and will be some
coupling between the two on an antenna (if you measure antenna Z
with/without a choke they will usually differ).

To place the choke in the best spot, you need to measure the common
mode current on the feedline and not the load impedance. If you have
common mode currents induced by an unbalanced situation in the antenna
itself, right at the antenna is probably best. Other places might be
good if you are coupling electrical noise to your feedline.
W1HIS's article was most interesting in this respect.

I would assume that because the feedline current is common-mode (the
same in both conductors), it will usually travel at the velocity factor
of a wire in air rather than the feedline velocity factor, though I do
not know this.

73,
Glenn AC7ZN

4:1 balun question
 

wrote:
I would assume that because the feedline current is common-mode (the
same in both conductors), it will usually travel at the velocity factor
of a wire in air rather than the feedline velocity factor, though I do
not know this.

Seems like a reasonable assumption given skin effect and the
outside braid of the coax. Common-mode current also, no doubt,
forms standing waves with current minimums and maximums 1/4WL
apart. A choke would be most effective at a standing wave
common mode current maximum point.
--
73, Cecil http://www.qsl.net/w5dxp