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[TowerTalk] Re: antenna element vibration damping -how

To: <towertalk@contesting.com>
Subject: [TowerTalk] Re: antenna element vibration damping -how
From: bouwker0@planetinternet.be (Kerkhofs Luc)
Date: Wed Aug 13 10:32:01 2003
Anyone ever tried to fill up the elements with PUR ??

ON4IA, Luc

----- Original Message -----
From: <towertalk-request@contesting.com>
To: <towertalk@contesting.com>
Sent: Tuesday, August 12, 2003 7:52 AM
Subject: TowerTalk Digest, Vol 8, Issue 45


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> Today's Topics:
>
>    1. TIC Control box (Steve)
>    2. Chicago Tribune: Antenna Stirs Static Among Neighbors
>        (Rob Atkinson, K5UJ)
>    3. Wearing hard hats (Gregg Seidl)
>    4. Re: Chicago Tribune: Antenna Stirs Static Among Neighbors
>        (Jerry Muller)
>    5. Re: antenna element vibration damping - how (Jim White, K4OJ)
>    6. Re: Tribander problem (Jim White, K4OJ)
>    7. Re: Reverse rotation on Ham IV (Jim White, K4OJ)
>    8. Re:  Antenna element vibration damping - How (Jan Erik Holm)
>    9. Re: antenna element vibration damping - how (Jan Erik Holm)
>
>
> ----------------------------------------------------------------------
>
To: <towertalk@contesting.com>
> Date: Tue, 12 Aug 2003 00:27:38 +0100
> From: Steve <ve3tu@rac.ca>
> To: "towertalk@contesting.com" <towertalk@contesting.com>
> Subject: [TowerTalk] TIC Control box
> Message-ID: <3F38266A.495BCC12@rac.ca>
> Content-Type: text/plain; charset=us-ascii
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7bit
> Precedence: list
> Message: 1
>
> Just a shot in the dark but I would like to know if anyone has a TIC
> control box that they would like to sell?
>
> tu es 73 Steve VE3TU
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Tue, 12 Aug 2003 00:43:45 +0000
> From: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>
> To: towertalk@contesting.com
> Cc: k5uj@hotmail.com
> Subject: [TowerTalk] Chicago Tribune: Antenna Stirs Static Among Neighbors
> Message-ID: <Law14-F28nGotPlcoQs00016b07@hotmail.com>
> Content-Type: text/plain; format=flowed
> MIME-Version: 1.0
> Precedence: list
> Message: 2
>
> P. 1 of the Metro section of today's Chicago Tribune:
>
> Antenna Stirs Static Among Neighbors
> by John Keilman 8/11/2003
>
> Excerpts (summaries in [ ]):
>
> Carmen Ambroggio's lifelong passion for ham radio is all too obvious to
some
> people in his Park Ridge neighborhood.  They just have to look up.
>
> There, above his rooftop, is the steel antenna tower the 78 year old
retired
> businessman is building in his back yard so he can talk to people on the
> other side of the globe....
>
> But he has few sympathizers among his neighbors.  They call the $9,000
> retractable tower, designed to reach a maximum height of 64 feet, an
eyesore
> that is out of place in a community where even telephone wires are buried.
>
> "It's not appropriate for someone to move in and put something like this
in
> a residential neighborhood," said Robert Wallace, who lives a few houses
> away.  "It may be legal, but it shouldn't be legal."
>
> ..oppposition has led city officials to crack down on Ambroggio for
placing
> his tower a few feet farther into his yard than it should be, marking
> another skirmish in the long-standing battle between the nation's 685,000
> ham radio operators and the people living near them.
>
> [Paragraph describing ham radio public service leading to PRB-1]
>
> On the other side, many neighbors of radio operators have no desire to
look
> at the towers, which can reach heights of 75 feet or more...[cause]
> interference nearby...concerns prompted some municipalities and home
owners
> assns. to get tough on the towers.
>
> Park Ridge zoning laws allow antenna towers up to 75 feet...When some
> neighbors learned about his plan for a tower, they complained that it
would
> be out of place on their street of ranch and split-level houses.  After
> several months of deliberation, the city gave Ambroggio a building permit.
>
> Thomas Wong, chairman of the Elec. and Computer Eng. dept. at Ill. Inst.
of
> Tech. said interference could be due to improperly installed antennas or
> transmitters that send out too much power.  Home electronics also could be
> to blame if they are not properly shielded from outside radio waves, he
> said.
>
> [Neighbor Kevin] Goll was no fan of the tower to begin with, but as he
> watched construction proceed he grew more irritated as he realized that
the
> tower was not being placed where it was supposed to go.
>
> [Account of how Ambroggio found an uncharted drain pipe during tower base
> excavation]  Without getting clearance from the city, he moved the tower's
> base a few feet farther into his yard.  That made the antenna even more
> visible, Goll said.  "By being moved so far out, there's nowhere we can be
> on our back patio and not see this thing," he said.  "This structure is
not
> small."
>
> He and other neighbors appealed to the city [Ambroggio reportedly has to
> move his tower at a cost of $3,000].  To Ambroggio and his atty., Sheldon
> Epstein [also a ham], the complaints are tantamount to harassment..."It
> doesn't matter if [neighbors] have an aesthetic objection or not," said
> Epstein, ..."The community has passed an ordinance that permits it.  End
of
> argument."
>
> Two photos:  1.  Photo of Mr. Goll looking unhappy with retracted tower in
> background.  Caption:  Kevin Goll and other Park Ridge residents have
> complained about the ham radio tower in the yard of Carmen Ambroggio.
Goll
> says he now hears static and voices from his TV and stereo.
> 2.  Photo of Mr. Ambroggio in basement shack.  Caption:  Carmen Ambroggio
> says his 64-foot tower is legal and necessary to operate the ham radio
> equipment in his basement.
>
> Rob Atkinson
> K5UJ
>
> _________________________________________________________________
> Add photos to your messages with MSN 8. Get 2 months FREE*.
> http://join.msn.com/?page=features/featuredemail
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 11 Aug 2003 20:09:53 -0500
> From: "Gregg Seidl" <k9kl@gbonline.com>
> To: <TowerTalk@contesting.com>
> Subject: [TowerTalk] Wearing hard hats
> Message-ID: <03ab01c3606e$7359cd40$51c667d1@doubleknlvs8ml>
> Content-Type: text/plain;
> charset="iso-8859-1"
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7bit
> Precedence: list
> Message: 3
>
> I really wish everyone on the reflector would wear a hardhat.July 31 I was
> going to go up my tower and do some work.I took hold of the tower to start
> on my up and a nut from one the tower sections fell and drilled me right
in
> my..........hardhat.Scared the #$%$#& out of me but no damage to the
> noodle.Please wear a hard hat,I really think if I hadn't had mine on which
I
> just recently started to do I would not be typing this.   Gregg K9KL
>
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 11 Aug 2003 21:17:38 -0400
> From: "Jerry Muller" <k0tv@adelphia.net>
> To: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>, <towertalk@contesting.com>
> Subject: Re: [TowerTalk] Chicago Tribune: Antenna Stirs Static Among
Neighbors
> Message-ID: <011701c3606f$85726950$6701a8c0@JerryP4>
> References: <Law14-F28nGotPlcoQs00016b07@hotmail.com>
> Content-Type: text/plain;
> charset="iso-8859-1"
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7bit
> Precedence: list
> Reply-To: Jerry Muller <k0tv@arrl.net>
> Message: 4
>
> This guy got off easy. I live in "Live Free or Die" New Hampshire and had
to
> spend over $25K in legal fees to protect three towers on six acres that
are
> almost invisible. (New Hampshire Supreme Court, Marchand v. Hudson)
>
> Jerry, K0TV
>
> ----- Original Message -----
> From: "Rob Atkinson, K5UJ" <k5uj@hotmail.com>
> To: <towertalk@contesting.com>
> Cc: <k5uj@hotmail.com>
> Sent: Monday, August 11, 2003 8:43 PM
> Subject: [TowerTalk] Chicago Tribune: Antenna Stirs Static Among Neighbors
>
>
> > P. 1 of the Metro section of today's Chicago Tribune:
> >
> > Antenna Stirs Static Among Neighbors
> > by John Keilman 8/11/2003
> >
> > Excerpts (summaries in [ ]):
> >
> > Carmen Ambroggio's lifelong passion for ham radio is all too obvious to
> some
> > people in his Park Ridge neighborhood.  They just have to look up.
> >
> > There, above his rooftop, is the steel antenna tower the 78 year old
> retired
> > businessman is building in his back yard so he can talk to people on the
> > other side of the globe....
> >
> > But he has few sympathizers among his neighbors.  They call the $9,000
> > retractable tower, designed to reach a maximum height of 64 feet, an
> eyesore
> > that is out of place in a community where even telephone wires are
buried.
> >
> > "It's not appropriate for someone to move in and put something like this
> in
> > a residential neighborhood," said Robert Wallace, who lives a few houses
> > away.  "It may be legal, but it shouldn't be legal."
> >
> > ..oppposition has led city officials to crack down on Ambroggio for
> placing
> > his tower a few feet farther into his yard than it should be, marking
> > another skirmish in the long-standing battle between the nation's
685,000
> > ham radio operators and the people living near them.
> >
> > [Paragraph describing ham radio public service leading to PRB-1]
> >
> > On the other side, many neighbors of radio operators have no desire to
> look
> > at the towers, which can reach heights of 75 feet or more...[cause]
> > interference nearby...concerns prompted some municipalities and home
> owners
> > assns. to get tough on the towers.
> >
> > Park Ridge zoning laws allow antenna towers up to 75 feet...When some
> > neighbors learned about his plan for a tower, they complained that it
> would
> > be out of place on their street of ranch and split-level houses.  After
> > several months of deliberation, the city gave Ambroggio a building
permit.
> >
> > Thomas Wong, chairman of the Elec. and Computer Eng. dept. at Ill. Inst.
> of
> > Tech. said interference could be due to improperly installed antennas or
> > transmitters that send out too much power.  Home electronics also could
be
> > to blame if they are not properly shielded from outside radio waves, he
> > said.
> >
> > [Neighbor Kevin] Goll was no fan of the tower to begin with, but as he
> > watched construction proceed he grew more irritated as he realized that
> the
> > tower was not being placed where it was supposed to go.
> >
> > [Account of how Ambroggio found an uncharted drain pipe during tower
base
> > excavation]  Without getting clearance from the city, he moved the
tower's
> > base a few feet farther into his yard.  That made the antenna even more
> > visible, Goll said.  "By being moved so far out, there's nowhere we can
be
> > on our back patio and not see this thing," he said.  "This structure is
> not
> > small."
> >
> > He and other neighbors appealed to the city [Ambroggio reportedly has to
> > move his tower at a cost of $3,000].  To Ambroggio and his atty.,
Sheldon
> > Epstein [also a ham], the complaints are tantamount to harassment..."It
> > doesn't matter if [neighbors] have an aesthetic objection or not," said
> > Epstein, ..."The community has passed an ordinance that permits it.  End
> of
> > argument."
> >
> > Two photos:  1.  Photo of Mr. Goll looking unhappy with retracted tower
in
> > background.  Caption:  Kevin Goll and other Park Ridge residents have
> > complained about the ham radio tower in the yard of Carmen Ambroggio.
> Goll
> > says he now hears static and voices from his TV and stereo.
> > 2.  Photo of Mr. Ambroggio in basement shack.  Caption:  Carmen
Ambroggio
> > says his 64-foot tower is legal and necessary to operate the ham radio
> > equipment in his basement.
> >
> > Rob Atkinson
> > K5UJ
> >
> > _________________________________________________________________
> > Add photos to your messages with MSN 8. Get 2 months FREE*.
> > http://join.msn.com/?page=features/featuredemail
> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
> Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with
any
> questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 11 Aug 2003 22:56:29 -0400
> From: "Jim White, K4OJ" <k4oj@tampabay.rr.com>
> To: kr7x@comcast.net
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] antenna element vibration damping - how
> Message-ID: <3F38575D.1090309@tampabay.rr.com>
> References: <200308112005.h7BK5Ggq006500@contesting.com>
> Content-Type: text/plain; charset=us-ascii; format=flowed
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7bit
> Precedence: list
> Reply-To: k4oj@tampabay.rr.com
> Message: 5
>
> Thanks, Hank!
>
> That was interesting.
>
> ..more importantly, now I remember why I dropped out of engineering
school!
>
> :-)
>
> Jim, K4OJ
>
>
>
> kr7x@comcast.net wrote:
> > List members:
> >
> > The phenomina you are witnessing is called vortex shedding or
oscillation. It
> > is a function of natural frequency of the element, in this case a
cylindar with
> > l/d >25, and the weight per unit length plus the wind velocity.
> >
> > For those who wish to see some illustrations go to:
> >
> >               http://www.itsc.com/movvkv.htm
> >               http://www.mecaconsulting.com/vortex_shedding.htm
> >
> > For a ton of sites use google and type in "vortex shedding" .
> >
> > For those interested further now come some formulas:
> >
> > for straight cylinder  nat freq (f)= C/2*Pi*L Sqrt(E*I*g/w)
> >
> >              C=3.515 for 1st mode
> >              L= length of element
> >              E=Modulus of elasticity of element material
> >              I=Moment of Inertia of element cross section
> >              g= acceleration of gravity
> >              w= element weight per unit length
> >
> > IF the element is tapered then:
> >
> >                 f = 3.52*De/48*Le Sqrt(E*g/2*w)
> >
> >                 De= equivalent dia of tapered element
> >                 Le= equivalent length of tapered element
> >
> >                  De=D+Dend/2
> >                  Le= L*Sqrt(2*De/De+D)
> >
> > The critical velocity to induce oscillation is:
> >
> >                            v= f*D/S      S=Strouhal number =0.2
> >                                          D= D or De
> >
> > As can be seen as the natural frequency goes up the critical velocity
goes up
> >
> > When you add a rope inside an element then you have increased the mass
which
> > increases the unit weight without modifying any other component which
will
> > reduce the natural frequency and there by decreasing the critical
velocity.
> > This helps explain why these things occur at lower velocities.
> >
> > IF you taper the element then you reduce both the diameter, reduce the I
and
> > the w and reduce the length. The upshot is that the natural frequency
normally
> > increases thus the critical velocity increases.
> >
> > This occurs again at the next harmoinc natural frequency. The force
generated
> > at natural or resonant frequencies of structures increase/decrease very
quickly
> > at the resonant frequencies with very little change in velocity. So as
the wind
> > starts and if the critical velocity is reached vortex shedding and its
> > accompaning oscillations occur. As you pass through the critical
velocity point
> > then the vibration will damp out. If the wind speed continues to rise it
is
> > likely that it will approach the 2nd harmonic frequency velocity and the
> > oscillations will occur with additional node and so on.
> >
> > Which is better as far as mass increase via rope in the element or
tapered
> > elements ? Who knows.
> >
> > Which ever mechanism you choose it would be advantageous to have a
fundamental
> > natural frequency that would be high enough to exceed normal wind
velocities at
> > a given location. However this on a commercial basis would be very
difficult.
> >
> > In general if you use straight non-tapered elements use rope inside if
tapered
> > then I would think that the taper would be very dramatic as to lessend
Le and
> > De but not to the detriment of the I or stiffness of the section to
withstand
> > design wind and ice loadings. See not an easy answer with all kinds of
> > comprimises.
> >
> > This is my 1 euro input but I hope it expands the understanding behind
this
> > type of vibration.
> >
> > 73
> > Hank Lonberg, P.E.,S.E. / KR7X
> > Lonberg Design Group, Ltd.
> >
> >
> >
> >
> >
> >
> >
> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 11 Aug 2003 23:10:10 -0400
> From: "Jim White, K4OJ" <k4oj@tampabay.rr.com>
> To: RLVZ@aol.com
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] Tribander problem
> Message-ID: <3F385A92.8060005@tampabay.rr.com>
> References: <164.244512bb.2c697d97@aol.com>
> Content-Type: text/plain; charset=us-ascii; format=flowed
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7bit
> Precedence: list
> Reply-To: k4oj@tampabay.rr.com
> Message: 6
>
> have you tried parking a stupid load (oops dummy load) at the top end of
> the tower - far end of coax - to see if the coax might not be the source
> of your problems...
>
> I would not be surprised ot hear it was... or, a connector which is on
> its last legs...
>
> K4OJ
>
>
>
> RLVZ@aol.com wrote:
> > Here's the problem: A Hy-Gain TH3-Mk4 tribander works fine at 100
watts...
> > but with a KW the SWR goes up when used for an hour or so at 50% duty
cycle.  I
> > pulled the traps and all looked well except for a couple loose screws
which I
> > tightened but it didn't solve the problem.   I have also tried replacing
the
> > balun without success.
> >
> > Any idears what could be the culprit?
> >
> > Thanks!
> >
> > Dick- K9OM
> > _______________________________________________
> >
> > See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 11 Aug 2003 23:32:15 -0400
> From: "Jim White, K4OJ" <k4oj@tampabay.rr.com>
> To: va3pl@cuic.ca
> Cc: towertalk@contesting.com
> Subject: Re: [TowerTalk] Reverse rotation on Ham IV
> Message-ID: <3F385FBF.8010609@tampabay.rr.com>
> References: <007e01c35ddd$b6b4e590$0200a8c0@k1ttt1>
> <3F360E3E.3020003@jimaz.cz> <3F373C63.1050102@telia.com>
> <3F376A61.5000803@telia.com>
> <WorldClient-F200308111130.AA30140089@cuic.ca>
> Content-Type: text/plain; charset=us-ascii; format=flowed
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7bit
> Precedence: list
> Reply-To: k4oj@tampabay.rr.com
> Message: 7
>
> one should stay one....
>
> that is your system common for both the directional and brake "paths"....
>
> unfortunately my manual is not here but....
>
> I know 4 and 8 are the motor capacitor....
>
> so I would guess it just may be 2 and 3 that need switching....
>
> Lift the line and put you Voltmeter on there - see which combo moves
> when you hit the directional buttons!
>
> As memory serves its 24 volts I think
>
> K4OJ
>
>
>
>
> VeeAthreePL wrote:
> > I think I goofed somewhere with control cables (too many connectors and
> > too many splices) to the rotor and the rotor is rotaiting the other way.
> > When I press CW it rotate CCW. It is like CW and CCW are reversed. What
> > happen if I reverse wires connected to pin 1 and 2? Will the rotor
rotate
> > the way it
> > should?
> > Thanks
> > Andy - VA3PL
> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
> > TowerTalk mailing list
> > TowerTalk@contesting.com
> > http://lists.contesting.com/mailman/listinfo/towertalk
> >
>
>
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Tue, 12 Aug 2003 07:42:44 +0200
> From: Jan Erik Holm <sm2ekm@telia.com>
> To: towertalk@contesting.com
> Subject: [TowerTalk] Re:  Antenna element vibration damping - How
> Message-ID: <3F387E54.4030200@telia.com>
> In-Reply-To: <5.2.0.9.2.20030811133603.00b08088@mail.earthlink.net>
> References: <007e01c35ddd$b6b4e590$0200a8c0@k1ttt1>
> <5.2.0.9.2.20030811133603.00b08088@mail.earthlink.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
> MIME-Version: 1.0
> Content-Transfer-Encoding: 8bit
> Precedence: list
> Message: 8
>
> Thank?s for this info, very interesting. After reading this I
> can see that I did some right things.
> What I mean with my elements isn?t vibrating is that I can
> neither see or hear any vibration, I have had antennas I
> could both see and hear how it did rattle and then elements
> would fall off after some time.
> Now, there pritty well could be vibrations but if I neither
> can see or hear it I will consider that it doesn?t vibrate
> and the design correct.
> Perhaps better put then, no harmful vibrations.
>
> 73 and now over to hard hats / Jim SM2EKM
>
> PS: Since I have a woodpecker on my property I always have
> the hard hat on when being outdoors.
> ----------------------------------------------------------------
>
>
> Jim Lux wrote:
>
> > At 11:19 AM 8/10/2003 +0200, Jiri Sanda wrote:
> >
> >> To later responses.
> >> Jan - I would like to see some designs that DOES NOT vibrate at all.
> >> Until now I have not seen such a beast !!!
> >
> >
> > Any round element will vibrate in the wind...simple mechanics and
> > aerodynamics (shed vortices), and forms the basis of such things as
> > aeolian harps. The vibration might not be noticable, or it might be
> > quite significant, and in a high Q system (which many mechanical systems
> > are) the vibration might build up to a significant amplitude.
> >
> ,
>
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Tue, 12 Aug 2003 07:50:56 +0200
> From: Jan Erik Holm <sm2ekm@telia.com>
> To: towertalk@contesting.com
> Subject: [TowerTalk] Re: antenna element vibration damping - how
> Message-ID: <3F388040.4070801@telia.com>
> In-Reply-To: <200308112005.h7BK5Ggq006500@contesting.com>
> References: <200308112005.h7BK5Ggq006500@contesting.com>
> Content-Type: text/plain; charset=ISO-8859-10; format=flowed
> MIME-Version: 1.0
> Content-Transfer-Encoding: 8bit
> Precedence: list
> Message: 9
>
> Thank?s Hank very good explanation. Now nobody has to ask
> anymore and I can see I have done the right thing.
> Also I don?t have to explain anymore with my crummy English,
> but people doesn?t beleive me anyway, guess I have to
> live with that.
>
> 73 Jim SM2EKM
> ------------------------------------------------------------------
>
> kr7x@comcast.net wrote:
>
> > List members:
> >
> > The phenomina you are witnessing is called vortex shedding or
oscillation. It
> > is a function of natural frequency of the element, in this case a
cylindar with
> > l/d >25, and the weight per unit length plus the wind velocity.
> >
> > For those who wish to see some illustrations go to:
> >
> >               http://www.itsc.com/movvkv.htm
> >               http://www.mecaconsulting.com/vortex_shedding.htm
> ,
>
>
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>
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> End of TowerTalk Digest, Vol 8, Issue 45
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