WA3GIN wrote:
> Depends on the amount of protection and your budget.
>
> R-56 Motorola standard states that you ground the coax shield to the
> tower at the top, middle and bottom of the tower. You place your
> lightning protection at the bulkhead panel or entry panel to your radio
> room.
>
> Polyphaser protectors are commercial grade, used by wireless carriers
> and they make products for amateur use as well. Those units cost about
> $65. ea. These devices do a great job. We require their use on all our
> public safety radio system antenna installations.
But the Polyphaser units aren't listed "Antenna Discharge Units" are
they? (at least last time I checked their catalog) So what do you use to
meet the NEC requirement for ADUs? Or does your local AHJ allow the use
of bulkhead feedthroughs in a entrance panel that's bonded to the
grounding system?
>
> Most amatuers don't go to the trouble and expense but I think it is
> worth the expense esp. if your tower is tall and you live in a location
> where lightning storms are frequent.
Worth is pretty subjective. And that gets back to trying to describe
your requirements: downtime tolerance, capital available for installing
stuff vs replacing stuff that is unprotected, etc.
For instance, I'd venture that most folks don't do much lightning
protection for their mobile rig.
a) Cars don't get hit that often
b) It is difficult to design a good protection system
c) Most lightning damage I've heard about (from hams) has actually been
from induced transients on thing like power and phone lines, not from a
direct hit on the antenna.
d) your auto comprehensive insurance covers the replacement cost
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|