[TowerTalk] static drainage

[Jon Ogden]

Pete,

There's been HUGE discussions on the danger of disconnecting for lightning
protection.  A pulse on your feedline could literally jump through the air
in your shack looking for that lowest resistance path to ground.  And if you
disconnect via relay or switch, I doubt you get much protection there.  The
pulse would probably arc over your relay or switch and go right through your
equipment.

You want to do all you can to prevent the lightning from entering your house
or shack.  Relays, filters, chokes, etc. inside the shack just aren't safe.
If your RF safety choke in your PA takes a strike, it will probably blow the
heck out of that choke and possibly a good part of your amp.  If I remember
correctly, those chokes are pretty high inductances.  Lighting doesn't like
high inductance and may not even take that path.

Unless you disconnect outside your house/shack and physically remove the
cables, then I'd be very concerned.

Additionally, with the disconnect method, you either have to unhook all your
cables every time you leave the shack or risk having a storm/strike sometime
when you are not home, etc.

Even if you still chose to disconnect, having surge protectors outside the
shack at the tower base or at the place where you have your SPG is a MUCH
safer idea.

73,

Jon
NA9D


on 1/27/03 10:01 AM, Pete Smith at n4zr at contesting.com wrote:

> At 09:00 AM 1/27/03 -0600, Jon Ogden wrote:
>> Agreed.  With such protectors (ICE and Polyphaser both have DC grounded
>> models) there is no need for any other form of static drain.  Plus, I've
>> been told that with continuous static drain, it makes your receive quieter
>> as you aren't hearing any noise from static build up.
> 
> 
> On the other hand, I have consciously opted for the "disconnect everything"
> method of lightning protection.  Given that, couldn't I simply shunt an RF
> choke to ground inside the relay box at its output jack, so that any time
> an antenna is connected by relay, any static goes immediately to ground
> before it gets upstream to the radio?  For that matter, as long as I am
> using my amplifier, which has an RF safety choke to ground, don't I get
> equivalent protection?

-------------------------------------
Jon Ogden
NA9D (ex: KE9NA)

Citizen of the People's Democratic Republik of Illinois

Life Member: ARRL, NRA
Member:  AMSAT, DXCC

http://www.qsl.net/na9d   <- Updated on 1/22/03!!!

"A life lived in fear is a life half lived."