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Re: [TowerTalk] What Killed the Computers? was: Re: Grounding ofAmateur

To: "WA3GIN @ Arlington County, VA" <>
Subject: Re: [TowerTalk] What Killed the Computers? was: Re: Grounding ofAmateur Radio installations
From: Jim Lux <>
Date: Fri, 08 Dec 2006 15:16:57 -0800
List-post: <>
At 02:27 PM 12/8/2006, you wrote:
>There are surge protectors for phone lines, Satellite coax lines as well
>as Cable TV coax lines.  Just google your area of concern and you'll
>find lots of vendors.
>Most companies recommend a whole house protector followed by individual
>units at all electronic equipment service areas.

After seeing the analysis in the book, I'd really question the need 
for individual units at point of use (at least as they are 
implemented in the usual consumer devices).  What might actually be 
useful is something like a transient clipper at the service entry, 
followed by a suitable low pass filter (to turn a high voltage narrow 
spike into a long duration bump).

Likewise, at point of use, a good low pass filter might be a more 
useful device than a transient suppressor. Of course, such devices 
are substantially more expensive to build than a plug strip with a 30 
cent MOV. The well equipped scrounging ham, on the other hand, should 
be able to find lots and lots of line filters from Corcom, etc., 
available surplus and wire them up appropriately.  That lightning 
transient, after all, has most of the energy up in the hundreds of 
kHz range and higher.

{BTW, I suspect that it's all those filters that are present in most 
consumer equipment these days that's why Standler's test data showed 
that 1000V short duration spikes didn't cause any troubles}

Excepting the "nearby lightning strike" scenario, there isn't much 
way for a fast transient to be induced into your inside wiring.  This 
is assuming you don't have a big "noise generator" inside your house, 
in which case, you should be focussing on stopping the transients at 
the source. (Come on, just build that faraday cage for your 5kVA 
tesla coil and stop operating the electromagnetic quarter shrinker in 
the living room!)

OTOH, I can plausibly see a lot of surge/sag kinds of behavior (i.e. 
Vrms going up to 130 for a second) and conducted transients (from 
switching and/or lightning somewhere in the power transmission/distribution).

I readily confess that I live in a relatively lightning free zone 
(southern California) but we DO get a lot of line transients, 
especially when it's windy. (Tree touches line, faults, breaker 
trips, then recloses, propagating 50% amplitude transients hither and yon)



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