Many years ago I built a remote antenna switch that allowed feeding up to 4 antennas from the same feedline. The feedline also was used for the control signal, so no additional wires were needed.
It was a very simple circuit. The switch box at the top of the tower contained 5 coax connectors, two DPDT relays, two diodes, an RF choke and a couple capacitors. The control box in the shack contained 2 coax connectors, a 60-Hz power transformer, a 4-position switch, an RF choke, two diodes and a couple capacitors. The schematic is at http://www.cds1.net/~n1al/ham/ant_switch.GIF The electrolytic capacitors in the switch box may not be needed, depending on the relays. I believe I used 0.1 uF for the coupling and bypass capacitors something like 22 or 47 uH for the RF chokes. (A smaller choke might be required for VHF.) The transformer was chosen to provide the correct relay voltage. You may need to add resistors in series with the relay coils to fine-tune the voltage. Al N1AL On Fri, 2010-12-17 at 07:48 -0800, Jobst Vandrey wrote: > A small board to insert 12 volts DC on the Coax at the shack and a similar > board to pick it up at the antenna end to run relays or power remote tuners > without impacting the RF carried on the coax. I really do not want to run a > second set of cables just for this purpose. It would be great if it was > configured with some more or less standard DPDT relay positions (optional of > course) that could be populated as needed by the user to meet various > switching needs. > > MFJ does offer such a beast (4116 and 4117 without the relays) - but I admit > to some significant uncertainty in the quality of the design and the of the > components used in the manufacturing. > > Jobst Vandrey > AC0LP > > > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
