RXADS progress #2
Last week my RX antenna switching cards finally came in the mail from the PCB maker. Had to solder them up right away last week. =) The design came out just the way I wanted. There are 7 antenna inputs per card and possibility to extend to another card with additional 7 antenna inputs, so in total it will be possible to switch any of 14 RX antennas to any of 3 receievers. Theese cards will be in the forest about 150m away from the house/shack in a plastic box as described in an earlier post.
The relay matrix for each receiver is controlled by a 4-bit binary code, where the last bit is used only for switching to the extended card. All of the inputs are protected by RC low-pass filters and MOVs. The antenna inputs and outputs are protected by 90V gas discharge tubes. I added the possibility to connect preamps in the future with relays for that as well. Here are some pics of the finished cards.