TVS - transient voltage suppressors, are another choice (TransZorb tm by
Vishay) and have some advantages over MOVs on small signal lines. The
bidirectional versions are basically two zeners back to back and are
very fast and have sharper knee voltages than MOVs. see
http://www.vishay.com/docs/88301/15ke.pdf TVS are available from 5v to
500v and peak pulse power from a less than a watt to 30,000w Digikey
seems to have many sizes in stock.
I am also told that MOVs can generate RF noise once subjected to a large
surge, which was experienced from a surge protected 120v outlet strip.
However, I think MOV's are the better choice for motor and large frame
relay spike protection and whole building surge protection.
While either device can absorb some of the spike energy, the spike
current needs to go somewhere that doesn't cause other problems.
Grant KZ1W
On 10/4/2012 10:59 AM, Dick Green WC1M wrote:
I use these:
http://hr-micro.com/
In addition to having two MOVs and a fuse per line, the board can be
purchased without the enclosure so you can mount on the ground panel inside
a weatherproof box.
One thing to be very careful about: some modern rotator controllers, SteppIR
controllers, etc., have delicate semiconductors directly connected to the
signal wires. You need to select MOVs that have a low enough trigger point
to protect the semiconductors without going below the average voltage put on
the signal wires by the semiconductors. This can be something of a
challenge.
Though I use surge suppressors at both ends (tower and shack), I also
disconnect whenever the station is not in use during lightning season. If a
surge gets past the MOVs, it can find its way into all sorts of equipment in
your shack via the controller.
73, Dick WC1M
-----Original Message-----
From: Larry Loen [mailto:lwloen@gmail.com]
Sent: Wednesday, October 03, 2012 6:41 PM
To: john@kk9a.com
Cc: TOWERTALK@contesting.com
Subject: Re: [TowerTalk] Lightning protection and control wires
Thanks to all.
This is the sort of stuff I'm looking for; happy if you know of
something else, too.
I am looking to operate remotely at some point, so this sort of MOV
surge protection looks like part of the cost of that dream.
Larry Wo0Z
On Wed, Oct 3, 2012 at 11:31 AM, <john@kk9a.com> wrote:
Array Solutions makes a nice protector.
http://www.arraysolutions.com/Products/surge_arrestor.htm
To: TOWERTALK@contesting.com
Subject:[TowerTalk] Lightning protection and control wires
From: Larry Loen <lwloen@gmail.com>
Date: Wed, 3 Oct 2012 09:34:59 -0700
I really don't understand, quite, how to protect myself from lightning
coming down the various wires. I'm sure this will be crushingly
obvious to someone, but I'm clearly missing something.
I'll have wires to coax switches and, of course, the rotor.
I plan on doing all the grounding of the coax and even putting in one
of those special gadgets that "blow out" a ball of
whatever-that-substance-is for the non-ground signal on the coax. I
plan on putting in the grounding systems talked about in "Up the
Tower" and generally around here.
But, despite having "Up the Tower" I don't get how to really secure
control lines (e.g. to the rotor) as far as lightning goes.
Is there some gadget that does the job?
Have I overlooked something?
Do I just rely on the regular low impedance grounding system to take
up most of the energy and hope not much flows on these wires?
Larry Wo0Z
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