[Elecraft] A Mini Module I would love to see (AC0LP)

[Alan Bloom]

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
> 
> 
>   
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