[Elecraft] disconnecting antennas

[AJSOENKE at aol.com]

Some of the e-mails in this thread exhibit some disregard for the fact that  
the shield side of a coax cable feedline is as much a part of the antenna as 
the  center conductor. Simply disconnecting the coax from the rig doesn't 
necessarily  prevent it from drawing hundreds of amps of Megavolt electricity from 
following  that shield to a convenient ground nearby. If for instance you 
disconnect a  diple with RG-8 feedline and simply drop the PL-259 on the lawn. 
you'll most  likely save the rig but not necessarily the lawn. or anything 
attached to the  antenna. Likewise, unplugging a feed line at the back of the rig 
and dropping  the cable on the floor may be too close to the nearest outlet or a 
lamp cord to  prevent an arc-over to  the rest of the system.
Nothings going to stop  lighting that just traversed several thousand feet of 
atmosphere from "ignoring"  1/2 an inch of carpet, etc.  Most of us have been 
very lucky.  My  first experience with lightning discharge was listening to 
my Viking Ranger  during a particularly windy night in Golden Colorado as the 
static buildup  jumped from the plate to the cathode of the 6146B tube. I did a 
hasty removal of  the ant feedline and spent the rest of the night wondering 
where the static was  going at that time.

Last interesting experience was with what I believe  is called dry lightning 
- no clouds around for miles.  Atop Diablo Peak on  Santa Cruz Island 24 years 
ago this week, I was setting up for the annual UHF  contest. First job was to 
assemble antennas. The previous night we (the  assembled contest team) 
observed a rather impressive lightning display from a  storm near San Diego, about 
200 miles away. That morning about 8 am it was clear  and gentle breeze with 
evidence of T C activity about 80 miles to the North East  of us over the San 
Gabriel Mountains.  As we assembled the antennas, mainly  sliding 1/8" Alum 
welding rods through various boom  holes, we suddenly  noticed a melodic humming 
like a multitude of tuning forks vibrating around us.  The next thing we knew 
as we hastily dropped what we were doing was all the  vegetation, mainly a fine 
grass that grows about 10 " tall and all very dry this  time of year, was 
standing on end as if reaching for the sky and shaking  violently with a very 
noisy crackling sound..Note, this is not a golf course  turf, but a rocky 
mountain top of the coast of So Cal. We were moving very fast  to get off the top and 
down the cliff side about 1000 ft to the west, where  there is a small cave 
carved in the cliff side. No sooner had we cramped  ourselves into this minor 
cavity than a slight warm breeze came up and an  instant later we heard a 
tremendous crack-bang that we knew was a lightning  strike. We didn't know where it 
struck and we decided to keep our heads down for  about 1/2 hour before 
peeking out and over the edge of the embankment.   When we emerged and hiked back 
up the hill, it was just another pleasant clear  day to behold. We never could 
figure where the strike took place and there were  several 50 + ft towers up 
there. None of our gear was disturbed or anything else  we could see including 
our 220 / 6 M repeater system.  Never got over the  nervous feeling of 
lighting from a clear sky.  Later that afternoon Thunder  storms ravaged many 
stations while we were in contact with them. Wayne N6NB was  Mobile on Mt Pinos and 
rode out the core of one TC. Pt Mugu NAS 30 Mi to th NE  of us had a record 
rainfall that flooded the base with 3 ft deep runoff.   And we remained dry 
through it all. It's an annual thing to have the Monsoon  flow to the SE of here 
but about once every 10 years it sweeps through with very  unpredictable 
conditions.
 
73 all   - Al WA6VNN



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