base cement

Wed Jun 21 00:15:32 EDT 1995

On 19-JUN-1995 20:55:59.6 mraz said to JKAHRS
   > Pete, N4ZR, posted the results of his question re: tower base cement.
   > I have a related question that came to mind. I've heard that the rebar
   > in a tower base should not be connected to the tower because the base
   > may explode if the tower is hit by lightning. However, Rohn sells a 5
   > foot tower section that is meant to be buried in the base cement. Is
   > the exploding base just a ham myth?
   > 73
   > Kris AA5UO (->N5KM)
   > mraz at aud.alcatel.com

The HyGain SS(Self Supporting) Crank-ups also use a rebar cage with 3 plates
that are above the concrete.  The tower then bolts to these plates.  As a
retired Naval Officer, I have left more than a few of these cages
around the U.S.  Sort of monuments to Amateur Radio.  I always have grounded
the tower just outside the concrete block.  I now live in the land of
thunder storms (FL), have been hit once (Meltdown '92), but not on the
tower.  It came in through the telephone lines!

73, Hank
K2UVG
Niceville, FL (Baja Alabama)

>From Brian Short <ke7gh at PrimeNet.Com>  Wed Jun 21 04:29:47 1995
From: Brian Short <ke7gh at PrimeNet.Com> (Brian Short)
Date: Tue, 20 Jun 1995 20:29:47 -0700 (MST)
Subject: SSTV
Message-ID: <199506210329.UAA19418 at usr1.primenet.com>

I understand the 87 number.  The best way to pin it down would be to try!
Also, I see the contest free zone as an apeasement to put a stop to any
credibility that current complaints may have.  If one of the organizations
you mention receives contest complaints, they can be reminded readily that
there is a contest free zone, if only it would used.  Folks are slow to
accept change and over the long haul perhaps more folks than you think
would see the light.  The contest free zone could be a real argument 
stopper, in my estimation.  What do you think?  73 de Brian

> 
> On this thread....
> A contest free zone may appeal to us...BUT... If I am not a contester and you
> are telling me that on any given weekend I HAVE to move my daily
> net/sstv/ragchew in order to lessen interference for your contest, guess what
> I am going to tell you... (picture a universal gesture here)
> I understand the rational behind the idea of a contest free zone, but I also
> understand human nature, and the 87% of hams who do not contest will assume
> that WE ought to stay away from them, not the other way around.... I strongly
> urge that the idea of further sub bands be dropped... Moving the discussion
> of this topic into the national magazine forums, or into the ARRL's policy
> groups, or into the purview of the FCC subcommittees is more likely to result
> in significant restrictions on contesting, than it is too generate wide
> support for moving 87% of hams off THEIR frequency...
> 
> Notatum Bono...
> 87% is an estimate, plucked out of the 'aether'.
> Rational discussion welcomed..
> Flames go the curb with the kitty litter...
> 
> Denny                 k8do at aol.com
> 

>From BILL FISHER" <BFISHER at CONCEN.COM  Wed Jun 21 08:51:41 1995
From: BILL FISHER" <BFISHER at CONCEN.COM (BILL FISHER)
Date: Wed, 21 Jun 95 07:51:41
Subject: Contest Free Zone ??
Message-ID: <9505218037.AA803746301 at concen.concen.com>

     I've been auto-trashing this SSTV thread until I saw something from 
     Tree.  Someone must have suggested a contest free zone?

     Hello McFly?  We already have one:  WARC.

     Don't be too quick to cave in guys... We aren't on the bands that 
     much.  Just when we are, we're loud and there's lots of us.

     73

>From Peter G. Smith" <n4zr at netcom.com  Wed Jun 21 13:27:32 1995
From: Peter G. Smith" <n4zr at netcom.com (Peter G. Smith)
Date: Wed, 21 Jun 1995 05:27:32 -0700 (PDT)
Subject: exploding bases
Message-ID: <Pine.3.89.9506210549.A2890-0100000 at netcom20>

About half the people who responded to this question seem to have assumed 
it was from me, because I was quoted in the message.  Not so.  The query 
came from Kris (AA5UO,   mraz at maverick.aud.alcatel.com).  I'm skeptical 
about it, myself, and nobody who e-mailed me has reported personal 
experience with the alleged phenomenon, while a number reported 
extensive, negative results.

73, Pete                                       
N4ZR at netcom.com
"Better, faster,cheaper -- choose any two"
"No no no -- it's WEST Virginia"

>From wrt at eskimo.com (Bill Turner  W7LZP)  Wed Jun 21 13:30:00 1995
From: wrt at eskimo.com (Bill Turner  W7LZP) (Bill Turner  W7LZP)
Date: Wed, 21 Jun 1995 12:30:00 +0000
Subject: Which vertical
Message-ID: <199506211230.AA17215 at mail.eskimo.com>

Hi Rick:  I know you asked about verticals, but if I may make a suggestion,
you'd be better off putting up something horizontally polarized.  The simple
dipole or inverted vee will work out better than a vertical, unless you can
put down a truly humongus set of radials.  The ARRL antenna book has a good
(but pretty technical) discussion of horizontal vs vertical and the effect
of ground reflection on each.  Over ordinary earth with the "usual" number
and size of radials, horizontal wins easily.  The same effect is shown by
the various antenna modeling programs such as Elnec.  Over "perfect" earth
or salt water, the vertical does well, but over "real" earth, it will be
roughly two to five db down.  Us contesters need every db we can get.  Good
luck!!

73, Bill  W7LZP
wrt at eskimo.com

>From wrt at eskimo.com (Bill Turner  W7LZP)  Wed Jun 21 13:38:16 1995
From: wrt at eskimo.com (Bill Turner  W7LZP) (Bill Turner  W7LZP)
Date: Wed, 21 Jun 1995 12:38:16 +0000
Subject: base cement
Message-ID: <199506211238.AA18211 at mail.eskimo.com>

At 12:15 PM 6/20/95 -0400, K8DO at aol.com wrote:
>Hi...
>How many tower bases have 'exploded' to the PERSONAL knowledge of any ham you
>know? How many tower bases for TV antennas have exploded in your community?
> How many radio/tv broadcast towers have had this happen in your community?
>
>I rest my case......
>
>Denny               K8DO at AOL.COM
>
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Living on the lightning-deprived west coast, I've never known of one
exploding.  Just as a thought, if one were to explode it probably would be
from entrapped water being turned to steam.  This would imply that you
should do your best to seal the area where the tower base goes down into the
concrete.  If your tower's been up a while, it's probably too late to worry
about it, though.  

73, Bill  W7LZP
wrt at eskimo.com

>From Stankiewicz, Warren,  NF1J" <wstankiewi at arrl.org  Wed Jun 21 13:56:00 1995
From: Stankiewicz, Warren,  NF1J" <wstankiewi at arrl.org (Stankiewicz, Warren,  NF1J)
Date: Wed, 21 Jun 95 08:56:00 EDT
Subject: exploding bases
Message-ID: <2FE819FB at arrl.org>

I've never heard of this phenomenon myself.

I wonder though--if lightning hit a recently poured base, where there was 
still a fair amount of water involved, couldn't that water turn into steam 
and then cause the "exploding base" phenomenon?

73,

Warren, NF1J

Disclaimer--my thoughts and opinions, not my employers.

>From Mitch, WA4OSR" <fmitch at maf.mobile.al.us  Wed Jun 21 14:02:59 1995
From: Mitch, WA4OSR" <fmitch at maf.mobile.al.us (Mitch, WA4OSR)
Date: Wed, 21 Jun 1995 08:02:59 -0500 (CDT)
Subject: Vibroplex now on contest reflector
Message-ID: <Pine.SOL.3.91.950621080143.5510B-100000 at ns1>

just a note to let everyone know that Vibroplex is now on the contest
reflector...

mitch
wa4osr

         * * * The *FIRST HAM OWNER* of The Vibroplex Co., Inc. * * *
-------------------------------------------------------------------------------
Email:  fmitch at maf.mobile.al.us   or, second choice, fmitch at rd.qms.com
 Felton "Mitch" Mitchell, WA4OSR
 The Vibroplex Co., Inc.
 11 Midtown Park, E.
 Mobile, AL 36606-4141 USA
 334-478-8873 Vibroplex, 334-342-7259 home, 334-476-0465 FAX
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