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base cement

Subject: base cement
From: JKAHRS@delphi.com (JKAHRS@delphi.com)
Date: Wed Jun 21 00:15:32 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@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
Niceville, FL (Baja Alabama)

>From Brian Short <ke7gh@PrimeNet.Com>  Wed Jun 21 04:29:47 1995
From: Brian Short <ke7gh@PrimeNet.Com> (Brian Short)
Subject: SSTV
Message-ID: <199506210329.UAA19418@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@aol.com

>From BILL FISHER" <BFISHER@CONCEN.COM  Wed Jun 21 08:51:41 1995
Subject: Contest Free Zone ??
Message-ID: <9505218037.AA803746301@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.

>From Peter G. Smith" <n4zr@netcom.com  Wed Jun 21 13:27:32 1995
From: Peter G. Smith" <n4zr@netcom.com (Peter G. Smith)
Subject: exploding bases
Message-ID: <Pine.3.89.9506210549.A2890-0100000@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@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                                       
"Better, faster,cheaper -- choose any two"
"No no no -- it's WEST Virginia"

>From wrt@eskimo.com (Bill Turner  W7LZP)  Wed Jun 21 13:30:00 1995
From: wrt@eskimo.com (Bill Turner  W7LZP) (Bill Turner  W7LZP)
Subject: Which vertical
Message-ID: <199506211230.AA17215@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

73, Bill  W7LZP

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

At 12:15 PM 6/20/95 -0400, K8DO@aol.com wrote:
>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@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

>From Stankiewicz, Warren,  NF1J" <wstankiewi@arrl.org  Wed Jun 21 13:56:00 1995
From: Stankiewicz, Warren,  NF1J" <wstankiewi@arrl.org (Stankiewicz, Warren,  
Subject: exploding bases
Message-ID: <2FE819FB@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?


Warren, NF1J

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

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

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


         * * * The *FIRST HAM OWNER* of The Vibroplex Co., Inc. * * *
Email:  fmitch@maf.mobile.al.us   or, second choice, fmitch@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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