[HiDARG-MEMBERS] Ununs & Baluns

[Max Vaughan]

Look for the book.

"Understanding, Building, and Using Baluns and Ununs"

Jerry Sevick W2FMI

 

Both are TLT devices... Transmission Line Transformers

 

Basically the jest of the book is when to use what and where/why and making
your own..

Baluns go from a balanced line to an unbalanced line.

And Ununes are for unbalanced to unbalanced. (not as common)

 

Baluns are most commonly used to keep voltage from getting onto the outer
shield of 

your feed line in the case of coax, and to match that 50 ohm coax to several
hundred ohms worth of antenna's.

 

To better simplify this, try not to think about what you need and when/where
you should use it.

Think of how you are running the signal from your radio to the antenna.

Coax/ladder/ combo... and what kind of antenna you have.

 

The book advises that if you want to know why/where/when/how to use TLT's

you should take a graduate course in electronic transformer theory.

 

BUT KEEP IT PRACTICAL..

When in reality you just need to know that your transmitter is designed for
50 ohms and you need

to ensure that  as much voltage/current gets to the antenna..not on the
outside of your coax

and reflected back to your radio..(your tuner helps to do that, it makes
sure that the radio see's a 50 ohm

antenna, and that your antenna sees a radio that is at the same ohms as the
antenna.)

Most of the TLT's job is to make sure that the current/voltage stays in the
coax and is going out the antenna...

 

The TLT just converts one impedance to another and makes sure as much of the


power on one side gets to the other side, with little loss.

 

Think about your stereo..it recommends that you use 8ohm speakers, your only
have 4ohm speakers.

So you get a 4 ohm resistor (tuner) and put it in series with your speaker.

Your stereo sees 8 ohms but only half the power gets to the speaker. The
rest is heat in the resistor.

 

So instead you put two 4ohm speakers in series now your speaker is matched
and no loss of power.

Simplistic view, but you get the idea.

 

The first question is what kind of antenna and what the designed impedance
is.

Then how are you feeding it... coax or ladder, end fed???

Then chose the proper ratio recommended for the antenna design

Build your own or buy one. Make sure it can handle the current(watts) your
good to go.

 

73 

Max Vaughan KF7MAX  Secretary

High Desert Amateur Radio Group

PO Box 723

Bend, Oregon USA   97709

541-706-1475

www.hidarg.org <http://www.hidarg.org/>  

maxv at horizonps.com <mailto:maxv at horizonps.com>       

kf7max at arrl.net <mailto:kf7max at arrl.net> 

 

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