I've been enjoying several Lazy H antenna I built for 10 meters that
are being fed with 450 ohm ladder line back to the tuner. They
antennas are performing well. The problem is the external baluns I am
using back at the tuner heat up even at 100 watts. These are suppose
to be 1.5 kw baluns, but they can't handle the impedance mismatch for
full legal limit. I have commercial 1:1 voltage baluns and 4:1
voltage baluns.
I decided to build an air core balun in hopes of saving myself the
expense of buying several torrid cores. The problem is none of the
plans listed in the Bill Orr handbook or that I have found on the
Internet actually work. On my one commercial 4:1 balun if I place a
200 ohms resistor across the leads of the balun I get an SWR reading
of about 1.1:1. When I build the air core balun listed in the William
Orr handbook I get a 2.5:1 SWR.
Hmm..So I decided to try some 4:1 air core balun designs off of the
Internet as well. I found the web page below;

"A 4:1 Air-wound Balun"
http://combotec.com/projects/balun14/balun14.html

I built the balun exactly like the web page described. It does not
work. 2.5+ SWR on 10 meters with a 200 ohm resistor plugged up to the
terminals. The same 200 ohm resistor shows close to a 1.1 on a
ferrite 4:1 balun.

So, the Bill Orr 4:1 air core balun listed in his handbook does not
work on 10 meters. Neither does his 1:1 air core balun when tested on
10 meters with a 50 ohm resistor. The 4:1 air core balun listed on the
web page above does not work either. I'm getting tired of building
air core baluns that don't work.

So....,does anyone have any plans for a 4:1 air core balun for feeding
450 ladder from a tuner that you have actually tested and used that
and it shows close to a 1.1:a SWR when presented with a 200 ohm load?

By the way, of the 4 or 5 1:1 commercial baluns I purchased back in
the 1990s only one of them actually shows a 1.1:SWR when presented
with a 50 ohm load. The others show between a 1.7:1 and 2.1:1 SWR on
10 meters, and that is among several baluns that were all the same
model from the same manufacturer. I'd post the brand name, but the
paper brand labels wore off years ago. I can tell you it has little
brass machined screws and brass holders on the sides of the balun and
not the piece of copper wire coming out to the eye hooks. They are
enclosed inside the typical white PVC pipe with caps on each end and a
coax connector at the bottom.

Michael Rawls
KS4HY

On Jul 2, 6:10*pm, Michael wrote:
I almost forgot ..They need to be air core baluns that can easily
handle legal limit.

Thank you.

Michael Rawls
KS4HY

Michael wrote in news:e820bd25-b016-45f3-9511-
:


I've been enjoying several Lazy H antenna I built for 10 meters that
are being fed with 450 ohm ladder line back to the tuner. They
antennas are performing well. The problem is the external baluns I am
using back at the tuner heat up even at 100 watts. These are suppose
to be 1.5 kw baluns, but they can't handle the impedance mismatch for
full legal limit. I have commercial 1:1 voltage baluns and 4:1
voltage baluns.

Therein lies a possible explanation of your problems.

If you view the 4:1 voltage balun as device that can transform any load
from say 5+j0 to 5000+j0 (just staying on the X=0 axis) at 1kW (for
round numbers), you expected it to handle 15A, and withstand 3000Vpk,
over more than a decade freqency range, and to have a maximum loss of
say 20W (which is about enough to heat the core in most enclosures to
Curie point) or 98% efficient.... and then give a near ideal impedance
transformation.

Well, it just doesn't happen that easily... as you now know.

Owen

On 2 Jul,
Michael wrote:

So....,does anyone have any plans for a 4:1 air core balun for feeding
450 ladder from a tuner that you have actually tested and used that
and it shows close to a 1.1:a SWR when presented with a 200 ohm load?

Why not just use a(n electrical) half wave loop of coax if you are only using
it on 10metres? Or even just a Pawsey stub for a balun and match elsewhere.
You can do a lot of (single band) matching with just a quarter wave of open
wire line with shorts/open circuits and taps.

--
BD
Change lycos to yahoo to reply

Hey OM
The baluns I like to use are choke baluns and real transmission line
baluns, for ten meters and a 66% velocity factor coax that is 11ft of
RG213. That is 4:1 on ten meters only. And the high current, high
voltage nodes are at the ends of the coax.
73 OT
de N8ZU




On Jul 3, 6:50*pm, wrote:
On 2 Jul, *
* * *Michael wrote:

So....,does anyone have any plans for a 4:1 air core balun for feeding
450 ladder from a tuner that you have actually tested and used that
and it shows close to a 1.1:a SWR when presented with a 200 ohm load?

Why not just use a(n electrical) half wave loop of coax if you are only using
it on 10metres? Or even just a Pawsey stub for a balun and match elsewhere.
You can do a lot of (single band) matching with just a quarter wave of open
wire line with shorts/open circuits and taps.

--
* BD
* Change lycos to yahoo to reply

raypsi skrev 2011-08-10 15:43:
Hey OM
The baluns I like to use are choke baluns and real transmission line
baluns, for ten meters and a 66% velocity factor coax that is 11ft of
RG213. That is 4:1 on ten meters only. And the high current, high
voltage nodes are at the ends of the coax.
73 OT
de N8ZU




On Jul 3, 6:50 wrote:
On 2 Jul,
wrote:

So....,does anyone have any plans for a 4:1 air core balun for feeding
450 ladder from a tuner that you have actually tested and used that
and it shows close to a 1.1:a SWR when presented with a 200 ohm load?

Why not just use a(n electrical) half wave loop of coax if you are only using
it on 10metres? Or even just a Pawsey stub for a balun and match elsewhere.
You can do a lot of (single band) matching with just a quarter wave of open
wire line with shorts/open circuits and taps.

--
BD
Change lycos to yahoo to reply


I have had success using a construction similiar to:

http://www.arising.com.au/people/Hol...h/CM4Balun.htm

Two coils are made out of two pieces 75 Ohm coax, each 4m long.
As coil forms i'm using tubular foam pipe isolation. I dont know
the correct word for them in English The type used has a diameter
of 6 cm.


These baluns has served me well. Using TV-coax, the whole construction
wheights very little.


73
Ben / SM0KBW

This post is for anyone who finds this thread, and wants to know what my working solution is.

I purchased several 4:1 five killowatt baluns from Universal-Radio.com. The brand name and model number is "Hy Power GU4-HF-5KWS". When I tested these baluns with a 200 ohm resistor they showed a 1:1 match. I adjusted the length of the 450 ladder line coming from the Lazy H antennas to find the point where the tuner required the least amount of inductance to bring the system to resonance. The balun stayed much cooler this way. In retrospect I probably could have used a 1:1 balun as well. The length of the ladder line makes a huge difference in how hot the balun gets for a certain amount of power at the design frequency.

The Hy-Power 4:1 balun is Guanella Current HF Balun. It works well and the Lazy H antennas have been performing beautifully.

Thanks for all the replies.

Michael

On 09/17/2013 09:16 AM, Michael wrote:

This post is for anyone who finds this thread, and wants to know what my working solution is.

I purchased several 4:1 five killowatt baluns from Universal-Radio.com. The brand name and model number is "Hy Power GU4-HF-5KWS". When I tested these baluns with a 200 ohm resistor they showed a 1:1 match. I adjusted the length of the 450 ladder line coming from the Lazy H antennas to find the point where the tuner required the least amount of inductance to bring the system to resonance. The balun stayed much cooler this way. In retrospect I probably could have used a 1:1 balun as well. The length of the ladder line makes a huge difference in how hot the balun gets for a certain amount of power at the design frequency.

The Hy-Power 4:1 balun is Guanella Current HF Balun. It works well and the Lazy H antennas have been performing beautifully.

Thanks for all the replies.

Michael

Hello, and what is the bandwidth (in terms of a ratio) in which the
balun is expected to operate? Transmission-line baluns not
incorporating ferromagnetic materials have been around for a long time
but they're relatively narrow band devices. (Baluns using tapered
transmission lines and providing bandwidths approaching 1000:1 can be
constructed but aren't generally off-the-shelf available). Sincerely,
and 73s from N4GGO,

--
J. B. Wood e-mail: