[TenTec] OT: Openwire/Window Line and Bad Wx

Bob McGraw - K4TAX RMcGraw at Blomand.net
Tue Jul 30 15:04:50 EDT 2013


Further to this, a properly designed balanced feed system should balance the 
line to ground as opposed to just a balanced output or being balanced above 
ground.  Being properly designed, be it a balun or balanced tuner, it should 
provide a path to ground.  In effect the secondary at the center tap, should 
go to ground and not be floating.  Hence no further steps required to bleed 
off static build-up from wind, snow and etc.

On this point, any degree of unbalance in the system can be measured as 
current in the ground path between the CT of the balanced network and 
station ground.  Thus little to no current indicates a good balanced system. 
More current indicates some degree of unbalance with larger current values 
indicating greater degrees of unbalance.

73
Bob, K4TAX






----- Original Message ----- 
From: "Bob McGraw - K4TAX" <RMcGraw at Blomand.net>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Tuesday, July 30, 2013 12:10 PM
Subject: Re: [TenTec] OT: Openwire/Window Line and Bad Wx


> Yes, but lightning is not DC.  It is a series of short duration pulses 
> resembling AC and should be treated accordingly with little to no 
> inductance in the path.  Thus any inductance in line would actually 
> prevent the energy from going to ground.
>
> For lightning protection on balanced feed systems, see The Wireman model 
> #878 as one good example.   Just about every series fed broadcast tower 
> uses an "arc gap" method for that purpose.  I find that a pair of small 
> engine non resistive sparkplugs mounted on suitable hardware which is 
> adequately grounded does an excellent job and with no issues at legal PEP 
> power.
>
> The old knife switch approach is OK........... if one remembers to put the 
> switch in the proper position when lightning is around or the station goes 
> QRT.
>
>
> 73
> Bob, K4TAX
>
>
> ----- Original Message ----- 
> From: "Robert Arenella" <rja12 at comcast.net>
> To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
> Sent: Tuesday, July 30, 2013 8:01 AM
> Subject: Re: [TenTec] OT: Openwire/Window Line and Bad Wx
>
>
>>
>>> On 7/29/2013 11:31 PM, Richards wrote:
>>>
>>>  > A second question is what lightning protection devices are preferred
>>>  > for securing open transmission line?
>>>  >
>>>  > ===============  K8JHR  ================
>>>
>>> I'm not sure what is "preferred", but what I use is a large DPDT knife
>>> switch, one side to the tuner, the other position to ground.
>>>
>>> Although I don't use one, there is always the ever-popular dual spark
>>> gap as shown in the old (and maybe newer?) Handbooks.
>>>
>>> Finally, for static mitigation there is the high value resistor from
>>> each open wire conductor to ground.
>>>
>>> 73,
>>> Carter   K8VT
>>>
>>>
>>> _______________________________________________
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>>>
>>
>> Another option is to use a pair of plate chokes from each half of the 
>> feedline to ground.  I have a friend up in NH using this setup.  Keeps 
>> the antenna & feedline DC grounded.  Lightning isn't his big problem, 
>> static electricity generated by blowing snow was creating havoc at his 
>> station. The chokes solved the problem.
>>
>> 73 de bob,
>> N2OAM
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>> TenTec at contesting.com
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>>
>
>
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