Topband: Binocular Transformer Design

[Dennis W0JX]

Pete:
I can tell you from experience that a half-turn situation with a binocular core really screws up the balance of the transformer. I made several identical xformers and hooked them up back to back to check loss and SWR. The units with half-turns always had much higher SWR results.
 
For 75 ohm cable, use a 2 turn primary and 5 turn secondary. This means each hole will have two passes for the primary and 5 passes for the secondary. The 2 to 5 ratio results in a 6.25 impedance step up to 469 ohms. That is what I usually use on my beverages and my K9AY. I also recently tried a 3 turn primary and 7 turns secondary which results in a 532 ohm match. I cannot tell the difference in performance of my K9AY between the two xformers.
 
73, Dennis W0JX/8