Antenna Selector

Remote Antenna Selector

This device remotely selects 1 out of 4 antennas for each of the 2 feedlines independently.
Ideally it sits very close to the antennas so that you only need to route to the shack one or two long feedlines instead of all the antennas. It is controlled via the PC COM-port connected to an RS232-RS485 adaptor that feeds the control cable (4 wires). This cable may be as long as 1km, so the Antenna-Selector can be located 1km away from the shack to get out of a local noise zone.

2 feedlines are supported to allow phaser operation, each feedline selector acts independly of the other.
If you only need one feedline then you can arrange the device to select 1 out of 7 antennas.

In the shack you select the antenna via a menu or hotkey in StationList.
Even when running a remote-QTH environment you now can select the antenna.

Automated recording now also selects antenna

You predefine in StationList scheduler what antenna to use for each recording.

Block Diagram of a typical 2-feedline antenna system

Block Diagram of a typical 1-feedline system with max 7 antennas

The Antenna-Selector board is indicated by the dashed box.
Everything else has to be provided by you, except the RS232 adaptor.

The 2 torroid chokes prevent feedline noise coupling back into the antenna. Do not ignore them, they are essential for eliminating noise!

How to build the choke?
Wind RG174 coax on a ferrite torroid (type FT140-77) as tight as possible in one layer, similar as shown here
Do not wind a second layer, it will increase the capacitance between windings and attenuation will decrease at higher frequencies

The RS232-RS485 adaptor connects to the PC COM-port, a small power supply 12VDC also plugs into the adaptor and feeds the selector board. Power is only needed during a selector change. The relays remain in that state and power is no longer needed.

Each input is protected by a 90V gas discharge tube. (GDT)

Antenna Selector Board

All terminals are plugable, simply pull them off if you want to remove the board. Only 4 GDTs are mounted here.

Antenna Selector mounted in box (made by FiBox)

Antenna Selector in the field

The 2 chokes are also placed in the box

Component Set

The BNC adpators are not part of the set. It's an older photo, because I currently have no other.
The board option shown here has only 4 relays mounted to save cost

You need one?

Quite a few DXers showed interest in buying this Antenna Selector, so I decided to produce them in an one-run.

There will be no second run after that, and this page will be closed

The project has been closed now !