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: