I knew from the beginning of this project, that it would take a circuit board to contain what I wanted. I began with the BCD-10 decoder from Unified Microsystems (http://www.unifiedmicro.com/decoder.html) and I ran the outputs to a bunch of relays so I could use source voltage to switch the antennas, instead of just having sinking the voltage to ground. This worked, but every time I changed my antennas, I had to rewire it.
Next I added circuit boards with switching relays and jumpers on it so I could have a "programmable" antenna switching system. All I had to do was simply move jumpers around!
Then I wanted to get rid of the relays (after I counted over 50 relays to switch 12 antenna lines, and to allow manual selection of switches.) It was at this point that I looked into using a microprocessor to accomplish my goals. I knew nothing about such things, but was willing to learn. I found an ARRL course which was supposed to teach me how to program PICs (http://www.arrl.org/shop/ARRL-s-PIC-Programming-for-Beginners/), but I had a difficult time learning assembly language. When I switched to Swordfish Basic, suddenly programming became a reality. Along with a Hamstack board from SierraRadio (http://www.hamstack.com/hs_cpu.html), I finally was able to make something work! My first attempt had inputs for two radios, and outputs to the antenna switch, as it told me, through a serial connection to my computer, what was going on, and what antenna is connected to what radio.
It worked, but I wanted more. What about an LCD readout? And manual selection of the antennas if I wished? And selection of Dummy loads? And selection via the web? And alternate antenna selection? And...? I wanted more than the Hamstack board would do without lots of external shields and connections. Finally I discovered the Arduino Mega 2560 board with lots of I/O pins! The only problem was I had to learn a new programming language! But another benefit was I could program on the Mac instead of the PC. So... I sat down and designed the circuit board... about 10 times! It seems that I always left something off or got the pins backwards, or ... you name it, I got it wrong.
So I had a lot of expensive prototype boards which got wasted. It seemed that whatever circuit worked on my breadboard did not work when it was put on a circuit board! Go figure! Finally I designed a circuit which worked... mostly. After putting it together, I discovered that all the antennas switched great when the radio changed bands, and I was ecstatic! Then I turned on the amplifier and discovered that my circuit loaded down the BCD sensing lines so much that the amp would not automatically switch bands! So I looked through my junk box and found some line driver ICs which, when breadboarded, isolated the lines from the Amp! Success! Five years finally coming to an end! The circuit board information you find on this page is the final result. I'm still waiting for this PCB to arrive, but I'm sure (fingers crossed) it will work!
Below you will find the schematic and the PCB layout (right click on them to download a pdf copy.) I used the Eagle layout program, although there are others which will work also.