Topband: Binocular Cores

[Dennis W0JX]

Mike: What do you mean when you say the K9AY "failed misearably on 160?"  I have a K9AY here that I use on both 160 and 80. I use a type 73 binocular core with only a 2 turn primary and 5 turn secondary. That gives a turns ratio of 2.5 and impedance ratio of 6.25. My core, however, is longer than the usual units almost 1 inch long x .5 wide.
   
  With 75 ohm cable, the resulting match is 469 ohms which is a good match to the 450 ohm
  feedpoint of a K9AY. Mine seems to work better on 160 and below rather than 80.
   
  One item to check is your terminating resistor. It has to be optimized for each band. In my K9AY, I use a 390 ohm terminating resistor.
   
  73, Dennis W0JX/8

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