I use a a relay to disconnect to the vertical portion just above the bottom
matching coil, keeping all else connected.
I do not understand why the shield should be disconnected ?
If it carries RF back it could be decoupled by ground rods to shield or
chokes.Bu if he top section is open circuit, there would not be any signal to
carry back in the first place.
Raoul ZS1C
On Sunday, December 8, 2019, 2:30:00 PM GMT+2, Rob Atkinson
<ranchorobbo@gmail.com> wrote:
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.
73
Rob
K5UJ
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