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Re: [TenTec] If you ground it - it will come!

To: <k4qo@earthlink.net>,"Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Subject: Re: [TenTec] If you ground it - it will come!
From: <ve1bn@ns.sympatico.ca>
Reply-to: Discussion of Ten-Tec Equipment <tentec@contesting.com>
Date: Fri, 5 May 2006 13:00:34 -0300
List-post: <mailto:tentec@contesting.com>
Randy -

Right you are!!  Years ago when I had a Cushcraft R-4 vertical, mounted on a 
high-rise
roof, I followed the recommended grounding instructions.  A year later it 
got a direct hit, which blew the matching box and a couple of traps.

Needless to say, I replaced the antenna with an R-5 but left it ungrounded. 
Once hit, made
aware (hi).  It has been up at the same location for the past 10 years 
without any lightning
problems. As a protection in the shack, the coax is disconnected when the 
rig is not in use, and the AC power cord is pulled, just in case of a near 
EMF hit.

73 -  Don,  VE1BN




----- Original Message ----- 
From: "Randy K4QO" <k4qo@earthlink.net>
To: <tentec@contesting.com>
Sent: Friday, May 05, 2006 11:19 AM
Subject: [TenTec] If you ground it - it will come!


> With apologies to "Field of Dreams", what I mean is that just grounding
> things sometimes means that you are inviting lightning to go to ground
> there... through your equipment.
>
> In my line of work with commercial radio towers, I have found that
> sometimes it is a mistake to ground certain items.  Improvements in
> survivability were gained when certain protection points were removed.
> For example, a serial communication line was protected with a device and
> was always getting fried along with the device it was hooked to.
> Removing the protection actually caused the devices to survive for more
> than three years with no problems.
>
> At my QTH, I look for ways to remove paths like was described by the
> "RIP" post.   Details like replacing switcher wall warts with
> transformer based ones provide a slight measure of advantage.  The
> transformer ones have (admittedly small)  isolation from ground and the
> AC lines.  This isolates the router and cable modem (which is attached
> to the cable!) from the AC mains and doesn't "invite" the surge to use
> this path to go to ground.  I won't go into a full treatise about
> grounding but if you take the time to personify lightning surges and see
> what paths it can take to ground (via your AC power plugs), you might
> see some opportunities for isolation.  One more thought - I use a large
> linear supply with better transformer isolation to power the cable modem
> and router and my radio supplies are all linears for the same reason.
> No switchers for me!
>
> BTW, I have heavy surge arrestors at the cable entry point with ferrites
> on the cable on the house side of things to encourage the surges (that
> are basically an RF signal) to go to ground at the points I have
> provided outside the house.  Its my own brand of voodoo but it is based
> on observations garnered at the commercial sites.
>
> This is a topic fraught with lots of opinion and some science and I
> don't mean that you shouldn't ground your station.  The commercial sites
> frequently have some of the best grounding known to man and still see
> damage.  Of course, at the end of the day, your best defense is to
> totally isolate your prized possessions during the storms.
>
> 73,
> Randy
> K4QO
> _______________________________________________
> TenTec mailing list
> TenTec@contesting.com
> http://lists.contesting.com/mailman/listinfo/tentec
> 

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