If you have more than 1 antenna you will at some point get annoyed to switch them manually. There will be lots of situations where you are simply transmitting into the wrong antenna, especially in the battle of a contest. Don’t ask me how I know. 😉
FUNKAMATEUR magazine has a nice kit to switch up to 4 antennas remotely, the FA-AU 4.1 (pictured left together with the controller unit described here). The big advantage is it is mounted in an outdoor mast enclosure so besides the availibility to switch 4 antennas you can even do it “remotely” and thus save a lot of koax cable, you just need one into the shack. Nice!
As you can see on the other pages it would not be me if I would not have developed something automatic for it, too. 😉 So in FA 6/10 and 7/10 I introduced a PIC based solution that will decode different band outputs of transceivers. Selected band is stored together with the antenna selection you made so whenever you do a band change at the radio the automatic antenna switcher will select the right antenna for you, no need to do anything manually anymore. 🙂 Besides this the antenna switcher generates single band signals available on a separate socket that can be used for additional switching tasks, i.e. to switch bandpass filters or the like.
For band detection the following methods are supported/implemented:
- BCD codes (used by Elecraft, Yaesu, some logging software, etc.)
- ICOM band voltage (virtually every ICOM radio has it)
- Yaesu band voltage (used in the FT-817)
- manual mode (if you have a radio not supporting band signals, i.e. Kenwood)
Band detection mode, detected band as well as choosen (and stored) antenna are displayed on a standard 16×2 display:
FUNKAMATEUR liked the idea so much they decided to produce a kit out of it, too: the BX-162 can be purchased from their webshop. It includes an assembly manual (sorrily in German only, but most things should be self-explainatory), the PCB and all to-be-soldered components. Only thru-hole components are used. As the likes of people are different it is up to the builder to choose a fitting enclosure. I used the typical “euro enclosures”, i.e. this one by Proma.