=  NOW 35 WPM  =  TEXT IS FROM FEBRUARY 2022  QST  PAGE 51 =

ASK DAVE MYSTERY BALUNS, REVIVING A RADIO, DIPOLES, AND MORE ON SPLATTER
DETERMINING A BALUN OR UNUNS RATIO Q I HAVE A COMMERCIALLY MADE BALUN IN MY
JUNK BOX THAT I ONCE USED FOR A WHILE AND WOULD LIKE TO AGAIN, BUT THE
LABEL HAS FADED.  ITS EITHER 1 1 OR 4 1.  IS THERE ANY TEST I CAN DO TO
FIND OUT?  A ABSOLUTELY, AND YOU PROBABLY HAVE THE REQUIRED EQUIPMENT IN
YOUR HAM SHACK ALREADY.  YOU NEED A RESISTANCE OF KNOWN VALUE USE A
RESISTOR, OR EVEN YOUR DUMMY LOAD AS WELL AS AN ANTENNA ANALYZER.  PLACE
THE KNOWN RESISTANCE ACROSS THE OUTPUT TERMINALS OF THE BALUN, THEN CONNECT
THE ANTENNA ANALYZER AS THOUGH YOU WERE MEASURING SWR, I RECOMMEND SWEEPING
ACROSS A WIDE SECTION OF THE 80 METER BAND.  THE ANALYZER WILL TYPICALLY
MEASURE AND DISPLAY BOTH THE RESISTANCE AND THE REACTANCE.  ESPECIALLY IN
THE HF BANDS, THE REACTANCE SHOULD BE VERY LOW, BUT WERE JUST INTERESTED IN
THE RESISTANCE MEASUREMENT.  MY TEST SETUP IN FIGURE 1 USES A 100 RESISTOR.
ON THIS 4 1 BALUN WE WOULD EXPECT A READING OF APPROXIMATELY 25.  THE
ANTENNA ANALYZER ACTUALLY READS 28, WHICH IS CLOSE ENOUGH TO CONFIRM THAT
THE BALUN IS 4 1, AS INDICATED ON THE LABEL.  WITH A 1 1 BALUN, WE WOULD
EXPECT A READING APPROXIMATELY EQUAL TO THE VALUE OF THE RESISTANCE.
PLEASE NOTE THAT HAM RADIO QUALITY TEST GEAR IS USUALLY INEXPENSIVE AND MAY
GIVE RESULTS THAT ARE ONLY CLOSE TO THE EXPECTED VALUE.  AS YOU TUNE THE
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