Topband: K9ay loop not performing

Rob Atkinson ranchorobbo at
Sun Dec 8 07:29:37 EST 2019

If you open the tx antenna feedline for rx, from my experience, you
need to completely open the entire feedline, namely the coaxial cable
shield as well as the center conductor.   coaxial relays that maintain
conductivity of the shield when N.O. won't detune/isolate the tx
antenna.  I use a pair of open frame relays for this.  Fortunately on
1800 kc the Z bump is almost nonexistent.   What will govern your
choice of relay is tx power and tx time, and whether or not you
require QSK.  I do not, but if you do, you may have to consider
something like multiple paralleled reed relays tor speed and power, or
vacuum relays.


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