[time-nuts] time-nuts Digest, Vol 100, Issue 114

M. Simon msimon6808 at yahoo.com
Mon Nov 26 20:06:31 UTC 2012


If you get a direct hit pretty much nothing can save you. Except luck. Because, when you are trying to get signals in on the one hand and keep lightning out on the other, strange things can happen. 

 
I had a long wire about 100 ft long (outdoor length probably on the order of 80 ft.) around 10 ft above ground (year about '74 - Carbondale, Illinois). A Lafayette Radio Antenna Kit IIRC.  A spark plug lightning arrestor (gapped to .010) on the end of an 8ft pipe pounded into the ground and then into the shack with a knife switch ground for use  during storms. 

During a storm with every thing in order - knife switch closed - antenna thus grounded - I took a direct hit. It caused a 3 ft ball lightning to form inside. It was green and moved slowly in my direction as I backed away. I think it lasted about a minute but time sense in such situations is not very good so it might have been 10 or 20 seconds. Total movement from inception to collapse - around 10 ft. No eqpt. was damaged. XMTR was a Johnson Ranger and the RCVR was a Hallicrafters. Can't recall the model. It would have been a similar price rage for the time - both bought used. 

So ball lightning is real. I found out up close and personal. 

Simon

Engineering is the art of making what you want from what you can get at a profit.


Message: 2
Date: Mon, 26 Nov 2012 10:18:34 -0800
From: Mark Spencer <mspencer12345 at yahoo.ca>
To: Discussion of precise time and frequency measurement
    <time-nuts at febo.com>
Subject: Re: [time-nuts] Surge Arresters
Message-ID: <CF4183AD-9C33-4012-8563-B5575DEBA4F8 at yahoo.ca>
Content-Type: text/plain;    charset=us-ascii

I don't use one on my gpsdo feed line.   The shield of the feed line is grounded prior to it entering the house and I don't live in a lightning prone area.  The gps antenna I use apparently has diode protection to provide some immunity to near by lightning strikes.  Most of my radio antennas are dc grounded.  I also had a dedicated roof top ground system installed during some prior home renovations that the coax shields of my roof top antenna(s) are connected to.   This ground system is in turn connected to the electrical service ground out side of the house.  I'm hopeful the roof top ground will be a more attractive path to ground for lightning than the shields of the feed lines that run into the house that are connected to gpsdo's and radios that are in turn grounded via the electrical system in the house.

If I see a surge suppressor for a decent price on eBay I might re consider getting one, but I'm unsure if it would make much difference in my circumstances in the event of a direct hit.   I'm primarily interested in protecting the house and it's occupants.   The survival of the radios is a fairly low priority to me.

I hope I never get to find out what happens if my roof top antennas get hit by lightning.

Regards

Mark Spencer

Sent from my iPad


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