Topband: More - lightning protection on 4 sq

[Roger D Johnson]

Harold Smith wrote:
> 
>> Greetings everyone. . .
>>
>> I received several responses to my email regarding installation of 
>> lightning protection on my 160 meter four square.  Several people 
>> suggested I put a Polyphaser on the coax output of the Comtek box. . .the 
>> coax going to the rig.  In my case, the lightning did not enter the Comtek 
>> box via the coax going to the rig (it's buried with a Polyphaser on the 
>> rig end of the coax).  Lightning came into the Comtek box from one of the 
>> vertical elements of the array itself.
>>
>> Several people suggested spark gap arrestors, shorted 1/4 wave stubs, or 
>> choke shunts (ala Array Solutions) on the elements.  These approaches 
>> would, no doubt, help.  Unfortunately, I didn't get a firm answer to the 
>> real question.  Will the addition of the standard DC blocked Polyphasers 
>> (basically, a big series cap) installed on one end of each coax phasing 
>> line, alter and destroy the correct phasing of the array?  A couple of 
>> people said they thought it would but weren't sure.  It would seem that 
>> inserting a large amount of C in series with the phasing line would have 
>> to alter its electrical length. . . and ruin the phasing in the process. 
>> If so Polyphasers wouldn't work, leaving the spark gap, stub, or choke 
>> solutions.  Is my thinking on track?
>>
>> 73 . . . Dave
>> W0FLS

I did a quick EZNEC model and adding -4 Ohms reactance (.02 ufd)at the 
feedpoint of the verticals showed no change in F/B ratio. I would also
add a robust spark gap and an RF choke to act as a static drain.

73, Roger

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