[TowerTalk] Relay lightening protection

[Wolfert, William R.]

Gentlemen

 

I'm putting together a switchbox for a phased array. I had many spdt relays on hand so I'm using them. 2 relays per antenna will work fine. The array is an 8 circle 

(for 80m, hung off the top of the 160 Vertical) and I've used ON4UN's switching scheme (on page 11-65 of latest edition of LBDX). I'm located in central Ohio, with moderate thunderstorm activity in the summer. Since unused antennas must float, the relay contacts are spoken for. The 160 Vertical has a spark gap and I intend to put a spark gap at the base of each wire. The 160 antenna has 120 ¼wl radials and each 80 m element will have 64. Control wires are underground from the shack to the towers. I have bypassed the control wires at the phase box. The feed coax is grounded when not in use. Adding a third relay per element would allow me to ground the system when not in use, but I'd rather not have 3 relays per element. Are diodes across the relay coils necessary? And if so, how can I detect a failed diode (a short, correct?) before turning on the power? The entire system (house, towers, shack, etc) is properly grounded by SPG. Your input is appreciated. 

 

73, Bill WR8K