On 4/17/2019 1:40 AM, Ulrich Weiß wrote:
Would like to know how to feed the relay at the top of the vertical... regards Uli, DJ2YA
Run a single insulated wire from the bottom to the top of vertical. Connect a 0.1 uF bypass capacitor from the wire to the vertical at the top. Connect another bypass capacitor from the wire to the vertical at the bottom. Connect the coil of the relay across the upper bypass capacitor. I like to spiral the wire around the vertical just to hold it in place. You can also use cable ties or electrical tape to hold it. Wind a bifilar choke on a large high permeability (EG #33) toroid. Connect one end of the twisted pair across the bypass capacitor at the bottom of the vertical. The other end of the twisted pair from the toroid should also have a bypass capacitor across it. The conductor in the pair that is connected to the vertical should be connected to ground at the other end. This provides a DC ground for static drain purposes. The other conductor is where you feed in the coil voltage. The reason for this arrangement is that the DC currents due to the relay coil in the bifilar wires are equal and opposite. Therefore, the DC does not excite the toroid and saturate it or magnetize it. It also avoids generating any voltage spikes when the coil voltage is switched off. About 25 turns on the toroid will work (not critical). Rick N6RK _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector