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@Blomand.net>
To: "Discussion of Ten-Tec Equipment" <tentec@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@comcast.net>
To: "Discussion of Ten-Tec Equipment" <tentec@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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