I need a remotely controlled antenna switch for new tower in Kasperske Hory located on top of the tower
with capability to select one of 4 antennas, able to pass "usual power" and don't affecting SWR too much.
The switch should be controlled from operator position just by buttons (to be fast)
with possibility to attach computer control from contest programs.
The goal is also to use minimum wires - the control cable I have
is limited and I would like to spare the rest for other hardware at the tower.
I managed to get suitable relays at flee market (russian 24V models with 1 switching contact).
I have designed a circuit diagram that should meet my needs.
The most funny thing is the polarity switching between the wires in order to control 4 relays
over just 3 wires. Of course, there are more possibilies, but this is nice simple. Next step was PCB desing and manufacturing (see the picture bellow). I placed the control unit into plastic box.
The relay unit is on the top of tower in another larger protecting box wired with control unit in shack - all reliably working for several months already. No signs of interference with TX RF power in 500W range.
The relay box
Printed circuit boards
Download PCB design (Express PCB)
Inside view - shortly after it becomes "alive"
Control unit in box - final