Quick Answer: What Is A Balun And How Does It Work?

Is a balun necessary?

Yes, a balun is needed.

All balanced antennas such as dipoles, Yagis and hexagonal beams that are fed with unbalanced feed lines such as coax, require a choke balun.

Without a choke balun, common mode RF currents flow on the outside of the coax making the feedline act like another antenna..

Do TV amplifiers go bad?

Amps do go bad, especially in areas with frequent electrical storms. There doesn’t have to be a direct strike for a charge to be passing through an antenna to ground. Weak signals can be helped with amplification, but often the better solution is moving the antenna to a better location.

How does a current balun work?

The voltage balun forces equal voltage across the two sides of a balanced load and the current balun forces equal current through the two sides of a balanced load. The 1:1 current balun is usually nothing more than a simple transmission line (e.g. bifilar winding or coaxial cable) wound on a Ferrite core.

What is a balanced antenna?

A balanced antenna is one where the elements are fed and are of equal length on both sides such as a dipole antenna ( most but not in all cases).

How do you test a balun?

look for the nearest trash can. That tests the balun CM impedance when operating into a balanced load. A more severe test is to attach the grounded jumper first to one side of the series pair, and then to the other side, and check how much the SWR changes. Also, using low value resistors “desensitises” the test.

What is the purpose of a balun?

A balun /ˈbælʌn/ (portmanteau of “balanced to unbalanced”) is an electrical device that converts between a balanced signal and an unbalanced signal. A balun can take many forms and may include devices that also transform impedances but need not do so.

Does a balun reduce noise?

Whilst a balun is usually associated with reduced unwanted transmission line radiation (eg. from the feedline and power cord), a balun can also help minimise unwanted noise picked up by your feedline.

What is a TV antenna balun?

The Outdoor Balun/Matching Transformer (CM94444) is used to convert the 300 ohm antenna output to 75 ohms so that low loss coaxial cable can be used to transport the TV signals from the antenna to the TV set. It is called a matching transformer because it matches the 300 ohm antenna output to the 75 ohm coaxial cable.

Do I need a balun on my TV antenna?

If you want to connect an antenna with a coaxial connection to an older TV that uses a two-wire input, you’ll need to use a balun transformer because these are different types of circuits. The coaxial connection is an unbalanced circuit that carries a single signal on its center conductor.

Why use a balun on a dipole?

A dipole is what is termed a balanced antenna. In an ideal world a balun should be used with coaxial feeder (which is unbalanced) to make the transition between balanced and unbalanced systems. The use of a balun will prevent the coax radiating any power or picking up any noise.

When should I use an antenna balun?

A Balun is used to “balance” unbalanced systems – i.e. those where power flows from an unbalanced line to a balanced line (hence, balun derives from balance to unbalanced). As an example, consider a coaxial cable connected to a half-wave dipole antenna shown in Figure 1. Figure 1.

What balun do I need for a dipole?

The overall length of the multi-band dipole antenna should be shorter than one-half wavelength as shown in Table 1. For best efficiency, ladder line feed and a good antenna tuner with balanced connections are required. The ideal balun is a 1:1 ratio DX Engineering special application tuner balun.

Do I need a balun on my dipole?

Paul, a dipole does not *have* to have a balun. Having one may help prevent RF from coming down the line into the shack and may improve the radiation characteristics of the dipole, but I’ve run dipoles connected straight to coax without a problem. Put one up without a balun and see how it works for you.

Can a balun go bad?

Now you know. That balun is usually the thing that goes bad. It’s pretty durable and works well, but most baluns are simply printed circuit boards and with enough hot and cold weather, they can crack. At the same time, some of the wiring that connects parts of the antenna together or connects to the balun can crack.