Station switching system design

14 Oct 2013 by sm0w, No Comments »

My friend Mike SJ2W and me started discussing tiopics on station automation and integration over ten years ago, and Mike began forming a project called openASC, asc as in "Antenna Switch Controller". The initial demands would be to create some kind of device that would switch all TX and RX antennas. Turn rotators and monitor things such as output power and other data. The system should also be idiot proof! So in the heat of a contest battle you should not be able to break anything by running RF into "loose ends", ak.a get rid of the human factor. Mike already implemented the system at his site that he is building, you should follow the development there I have spent thousands of hours myself over the last years and finally now I have most of the system up and running althogh some parts as rotator control etc.. is still to be built.

We have 4 operating positions at the contest station with an option of another 2 for a full Multi-Multi operation. When I designed the relay matrix itself for the antenna switching I decided that the following chriteria would apply. SO2R operation with high isolation between rigs. M/S and M/2 operations and possibility for M/M as well. To complete that it shoud also be possible to route WARC antennas into the system for DX chasing outside of contests. this is how the antenna switching matrix ended up:

openASC_RF_PathsTo simply describe the RF matrix 4 operating positions go into 9×2 switch boxes that connect Band Pass Filters for an actual band to the correct operating position. After the band pass filters signals are routed to an auto tune amplifier and to power splitters one for each band. The power splitters have 4 antenna inputs each. So each band can have 4 separate antenna systems to shoot RF into several directions at a time. the poer splitters are build with a 12.5 to 50 ohm transformer which makes it possible to combine up to 3 antenna systems on the actual band simultaneously. It will also be possible to add single bands amplifiers in the future, one for each band to avoid "tuning" during contests. Theese will be a project for the future.

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OJØR Market Reef

OJØR Market Reef

OJØR is my callsign during visits to the barren rock of Market Reef in the middle of the Baltic sea. [&hellip