N3EG - 3 wire 9 port remote antenna switch
 


Your R (right) and L (left) relay switching voltages will be either positive, negative, or zero.  A "1" indicates the
relay switched on (or in its "transmit" condition) and a "0" indicates unswitched.  Using a three wire cable to the
control box (right, left, ground) , you get 9 possible conditions and 9 outputs. For example, a condition of -12v
on the right and +12v on the left gets you 17 meters.  +12v on the right and 0v on the left gets you 15 meters.
+12v on the right and +12v on the left gets you 12 meters.  Use diodes on each bank of relays to determine
which polarity will switch them from the correct line.  Relays should be coax relays such as ones from old
Motorola radios (trashpicked Motracs/Mocoms/Micors except UHF/Mitreks/Syntors) or similar.

NOTES:  Use 1000 uF capacitors on the relay coils if the contacts chatter.
                Put your favorite band on "all zeros" in case of cable cut or power failure.
                Put lower bands in the lower right hand corner where the loss of four relays will be less
                         due to the lower frequency.
                This becomes a 2-wire antenna switch when you use your rotor cable or coax for ground!