Grant,
In broadcast, we use both good grounding on everything and surge arresstors
on most low power equipment. I generally use PolyPhaser but there are
other suppliers. You are correct that the "professional" surge arrestors
are typically 250w or less.but there are (or at least was) QRO arrestors
aimed at the commercial HF and amateur market.
Good to hear that you are using DIN connectors. Until a couple of years
ago, I had never observed a DIN connector in the wild but now specify them
on all lower power FM transmitters.
On large AM and FM transmitters, good grounding and built in lightning
protection is typically all that is used. Not to mention that the output
sections are inherently capable of withstanding high voltages.
Another very effective method of lightning protection is to use toroids of
5,000µ J-material over power, control and antenna cables. Here is a link
to an article on Nautel's site. It really seems to work...
http://www.nautel.com/support/technical-resources/tips-n-tricks/05-04-2011/
Do center pin arrestors do anything? I believe so. Especially if the
antenna feed isn't a shorted type.
And as I tell my clients, "The best lightning protection in the world
becomes just that much more smoking junk in a mega-strike. We can stop the
small problems, minimize the major ones but never completely eliminate
lightning related damage."
Good luck,
<http://www.mag-inc.com/products/ferrite-cores/j-material>
On Wed, Aug 5, 2015 at 10:06 PM, Grant Saviers <grants2@pacbell.net> wrote:
> I'm wondering what commercial practice is re surge arrestors?
>
> I note the max power ratings for DIN connector arrestors is 250 watts at
> least at Tessco. Many are frequency selective. PolyPhasers claim 2500
> watts 1.5MHz to UHF.
>
> With top and bottom tower bonding to a ground rod grid and 125' to tower
> in a trench with the shack entry plate feedthrough grounded to a 200'
> perimeter footing Ufer, to center pin arrestors do anything useful?
>
> Tower and trench coax is all DIN terminated hardline, so it would make
> sense to connect to a DIN connector arrestor (if useful), but no such QRO
> animal seems to exist.
>
Kevin C. Kidd, CSRE/AMD
AM Ground Systems Company - WD4RAT
kkidd@kkbc.com -- 866-22-RADIO -- 866-227-2346
www.amgroundsystems.com
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