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Old 21-Dec-2010, 3:40 AM   #3
John Candle
Senior Member
 
Join Date: Jun 2010
Posts: 2,697
Balun / Matching transformer /

Have no polarity when used to match 300 to 75 and 75 to 300 in a typical tv antenna installation. The balun can be turned around and used in the other direction. An example is , a Winegard HD7082P antenna has 75 impedance connection and a preamp has a 300 impedance input , the coax from the antenna is connected to the 75 impedance end of the balun and the 300 impedance end of the balun is connected to the input of a preamp that has a 300 impedance input. Or it could be the other way around , the antenna has 300 impedance connection and the preamp has the 75 impedance input. A typical balun is a few turns of wire on a ferrite core. The inexpensive ones are a metal tube and the inside is easy to slide out of the tube , take it apart and have a look.

Last edited by John Candle; 23-Dec-2010 at 7:31 AM.
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