[TowerTalk] LRC - Lightning Retardant Cable
K8RI-on-TowerTalk at tm.net
Sun Jun 3 20:17:49 PDT 2012
On 6/3/2012 10:17 PM, Martin Sole wrote:
> I hadn't heard of this before and at first was rather sceptical, still am to
> some degree, but it appears to be real enough and might in some types of
> installation be effective. Here are a few links to information:
Based on my, and most every one else's feeble understanding of
lightning: Near as I can tell
They use a 3 layer/conductor consisting of a central conductor, and two
*wound* outer layers at *roughly* 90 degrees to each other which would
put them at 45 degrees to the center conductor and separated by a high
voltage insulation that has a high dielectric constant that is also high
temperature and fire resistant.
Theoretically, and I have to emphasize the "theoretically" it should be
capable of reducing, induced voltage spikes, BUT I'd have to see test
data to have much faith in anything beyond low to medium voltage induced
spikes. It would "likely" add another layer of protection for voltage
sensitive devices, but with the variability and unpredictability of
lightning you are always playing the odds where a nearby strike may be
suppressed via simple means to a direct hit from a super strike that
only divine intervention or luck can protect what ever.
A straight conductor has very little inductance, but even a large tower
can posses enough that a strike with a rapid rise time will cause the
current to build so fast that it becomes self quenching and the stroke
will jump off the tower sideways.
If I read the description correctly this conductor appears, or is
claimed to appear as two chokes on the cable that will cancel the
current from the lightning strike, making the cable appear to be much
longer than its actual dimensions.
Having seen a shorted 1 1/2" diameter, solid copper buss whip around
like a snake while the arc burned the ends back like a fairly fast
burning fuse, I have my doubts as the effectiveness at handling much
power. OTOH *most* induced spikes do not contain a lot of power and they
are of short duration. That, combined with not having seen any test
data leaves me having to reserve an informed judgement about the
performance under specific conditions.
BUT we recently had a rather long discussion on here about diminishing
So, until I could actually see the test figures and conditions I think
I'd stick with the more conventional methods of grounding and bypassing
for equipment protection that have proven effective for what they were
designed while keeping in mind that there is nothing that will give us
100% protection. A really big strike very close can induce enough
voltage into the unplugged power cord to do damage, but those are
extremely rare and you won't be concerned about the equipment until the
ringing in your ears is reduced to the point where you can again
understand speech and the tingling in your extremities is mostly gone.
Nerves are something else<:-))
> I also have the US Navy test report from 2004 on lrc RG-214 that states
> improvements in phase stability and local interference pickup.
> I am interested to know if any here have looked at this product or can
> indicate what value it might add to an installation. My own initial feeling,
> after I had suspended my instant disbelief, is that in most amateur
> installations it probably adds little real benefit in terms of lightning
> protection where much of the intrinsic protection comes from other elements
> in the antenna system or indeed the whole outdoor network of objects.
> Martin, HS0ZED
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