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Topband: FW: Relay lightening protection

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Subject: Topband: FW: Relay lightening protection
From: "Wolfert, William R." <WWolfert@columbuspolice.org>
Date: Wed, 28 Jan 2009 09:22:36 -0500
List-post: <topband@contesting.com">mailto:topband@contesting.com>
 

 

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 

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