‰ NOW 20 WPM ‰ TEXT IS FROM DECEMBER 2013 QST PAGE 49‰ REALLY JUST A VERY CLOSELY SPACED PARALLEL CONDUCTOR FEED LINE. BY USING THE RIGHT MIX OF FERRITE, THE CHOKE WILL CREATE ENOUGH IMPEDANCE ACROSS THE HF RANGE. FOLLOWING THE GUIDANCE OF JIM BROWNS, K9YC, TUTORIALS ON FERRITES AND CHOKES, I CHOSE A 2R4 INCH DIAMETER 31 MIX WITH A WINDING OF 10 TURNS. THE FERRITE TUTORIAL ESTIMATES THAT THE BALUNS CHOKING IMPEDANCE AT 7, 14, AND 28 MHZ IS 3000, 3500, AND 2000, RESPECTIVELY, AS SHOWN IN FIGURE 1. FOR THE BIFILAR WINDING, I USED TWOCONDUCTOR PVC INSULATED 16 ZIP CORD WHICH IS FINE FOR 100 W POWER LEVELS. IF YOU PLAN ON RUNNING HIGH POWER, USE 12 OR LARGER WIRE. FOR THIS CORE YOU NEED ABOUT 3 INCHES OF WIRE PER TURN PLUS THE CONNECTIONS AT EITHER END FOR A TOTAL OF ABOUT 36 INCHES OF WIRE, INCLUDING THE INPUT AND OUTPUT CONNECTIONS. THE BALUN ‰ END OF 20 WPM TEXT ‰ QST DE W1AW ƒ