One might string some protective cables to deflect the falling branches?
Possible?
Sent from my iPhone
On Dec 2, 2011, at 10:11 AM, towertalk-request@contesting.com wrote:
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> Today's Topics:
>
> 1. cushcraft D3W (Bill Feissner)
> 2. Force required on guys to cause catastrophic failure? Have
> your guys been struck by falling limbs? (John W)
> 3. Re: Which type of cable for a crank-up tower?
> (krishna kanakasapapathi)
> 4. Re: TowerTalk Digest, Vol 108, Issue 6 (Craig Clark)
> 5. Cost effective Tower height (Jim Thomson)
> 6. Re: Cost effective Tower height (K1TTT)
> 7. Re: cushcraft D3W (Bert Almemo)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Thu, 1 Dec 2011 15:10:22 -0500
> From: "Bill Feissner" <ai3q@pa.metrocast.net>
> Subject: [TowerTalk] cushcraft D3W
> To: <towertalk@contesting.com>
> Message-ID: <460D33EA25AF4B79BA8CBCC2AA7A0DCE@BILL>
> Content-Type: text/plain; charset="iso-8859-1"
>
> What kind of opinion s there about mounting a D3W 5 feet under a 402cd. The
> 402cd is about 5 feet above the top of the tower and can't go any higher. I
> can mount the D3W paralell to the elements or run it with the boom. I know a
> yagi would be better but I am out of tower space except for this area. I did
> at one time have a 40 rotatible dipole under a 5 el tribander running with
> the boom about 7 feet below it with no ill effects...any thoughts on this.
> thanks
> Bill, AI3Q
>
> ------------------------------
>
> Message: 2
> Date: Fri, 2 Dec 2011 04:29:20 -0800
> From: John W <xnewyorka@hotmail.com>
> Subject: [TowerTalk] Force required on guys to cause catastrophic
> failure? Have your guys been struck by falling limbs?
> To: <towertalk@contesting.com>
> Message-ID: <BAY163-W245EDC4253ADBDD35BF532A5B60@phx.gbl>
> Content-Type: text/plain; charset="iso-8859-1"
>
>
> This is a two-part question. There is a small survey at the end for those who
> have had a guy struck by a falling limb or tree.
>
> My main question is: Are there any engineers out there who can tell me how to
> calculate the downward force on a guy that would cause a breakage or
> catastrophic failure?
>
> The reason I ask is that regardless of where I place my to-be-built tower, I
> cannot avoid having guys passing through the woods, and I am in a high wind
> area.
> There are constantly limbs, and sometimes even trees of various sizes,
> getting knocked down by the wind.
>
> I realize that if a huge tree falls on a set of guys, it's probably all over.
> That's a risk I'll have to take, and I plan to monitor tree health closely.
> What I am more concerned about is the large number of limbs, some of which
> are fairly sizable, that fall when the wind blows.
>
> I can measure the weight of a typical limb. They are mostly 2 lbs. to 5 lbs.
> But let's say I want to plan for the occasional big one, say 75 lbs.
> If it falls from a height of 80' before hitting a guy, I can calculate the
> acceleration due to gravity and calculate the force it has using F=MA.
> (I will have to break out the college physics book to do this, but I should
> be able to do it!)
>
> Now that I know the force, I can compare that figure against the force needed
> to either a) snap the guy wire it hits, or b) put so much instantaneous
> tension on the guy that it causes the tower to buckle.
> (Sorry to cause the inevitable cringing here, but...) I assume the tower
> would probably buckle at the point of attachment of the guy below the guy
> that got struck.
> It's also a reasonable assumption that it is most likely to be the top guy
> that gets struck. Although it's also entirely possible that a tree off to
> the side falls down, and the top of the tree strikes a lower guy in the
> latter part of its trip to the ground.
> In that case, the force on the guy would have both a downward and a lateral
> component. It would also be a lot harder for me to remember how to calculate
> the striking force in that case.
>
> I assume that some of the other factors needed in order to make a correct
> calculation would be the tower type (Rohn 25G, 45G, or 55G), the guy material
> (which would be per factory spec), and the distance between the struck guy
> and the one above it or below it.
>
> I realize it's asking a lot for someone to provide the formula(s) needed to
> make this calculation, but if there is anybody out there who would know, I
> figured this would be the best place to find them! (Or is this something I
> can ask the tower manufacturer?)
>
> On a practical level, I'm sure there must be some of you who have had limbs
> fall on guys. I'm interested to hear:
>
> What size/weight of limb hit the guy?
> What was the tower configuration (height, type, and guy material)?
> Which guy got struck?
> How far did the limb fall?
> What was the result? Damage or no damage?
>
> Thanks for all input,
>
> John
> W2ID
>
> ------------------------------
>
> Message: 3
> Date: Fri, 02 Dec 2011 07:43:07 -0500
> From: krishna kanakasapapathi <kkanakas@cisco.com>
> Subject: Re: [TowerTalk] Which type of cable for a crank-up tower?
> To: John Lemay <john@carltonhouse.eclipse.co.uk>
> Cc: towertalk@contesting.com
> Message-ID: <4ED8C7DB.1070709@cisco.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> John et all,
> I just recabled my tower the past week. I found that the 5 year old
> (perhaps older) stainless steel cable
> showed signs of slight rust on the coiled up rounds on the drum of the
> winch.
> I was hoping that the prelube will prevent the corrosion on that part
> of the cable. I don't know if the polymer coat will stay intact on the
> exposed run of the cables.
>
> krish
> w4vku
>
> On 12/2/2011 4:34 AM, John Lemay wrote:
>> If you oil the cable, won't the oil wash off the first time it rains ?
>>
>> John G4ZTR
>>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] On Behalf Of krishna
>> kanakasapapathi
>> Sent: 01 December 2011 22:24
>> To: towertalk@contesting.com
>> Subject: Re: [TowerTalk] Which type of cable for a crank-up tower?
>>
>> For my Aluma tower, the company recommended the 7x19 stainless steel cable.
>> I have ordered the penetrating oil from champion radio to protect the cable.
>> Regardless, i plan to replace the cables every 3 or 4 years depending on
>> the condition.
>>
>> For a salty air environment, wouldn't stainless steel be better?
>> 73s
>> krish
>> w4vku
>>
>> On 12/1/2011 5:00 PM, Dan Levin wrote:
>>> Of course, if I knew who made it I would just get the manual and do what
>> they say. But I don't know who made it, so...
>>> I have an unidentified 65' crank-up tower, believed to be of English
>> origin. It needs to be recabled. The existing (original) cable appears to
>> be 5/16", but it might be 8mm or even 7mm (I am not where the tower is, so I
>> can't measure it exactly). Definitely bigger than 1/4". The tower lives in
>> a very salty, island climate.
>>> I am trying to figure out what type of cable to use - not which size, but
>> which material and construction.
>>> The easiest thing to find that seems appropriate is 5/16" 7x19 galvanized
>> steel.
>>> But, I have read that these towers usually use 6x19 LC (linen core) -
>> which I can find in plain steel, but not in galvanized.
>>> 1) Is galvanized the way to go in this situation?
>>>
>>> 2) Any sense of which construction is most appropriate? I assume 7x19
>> would be best if I can't find the 6x19 LC.
>>> 3) Anyone have a source of 6x19 LC galvanized 5/16" cable?
>>>
>>> ***dan, K6IF
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
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>
>
>
> ------------------------------
>
> Message: 4
> Date: Fri, 2 Dec 2011 08:59:04 -0500
> From: "Craig Clark" <jcclark@myfairpoint.net>
> Subject: Re: [TowerTalk] TowerTalk Digest, Vol 108, Issue 6
> To: <towertalk@contesting.com>
> Message-ID: <09c901ccb0fa$8e3c2280$aab46780$@net>
> Content-Type: text/plain; charset="us-ascii"
>
> Can we please edit responses. Delete is getting worn off my keyboard.
>
> There is no need to include everything when you respond.
>
> Thanks
>
> Craig
>
>
>
>
>
> ------------------------------
>
> Message: 5
> Date: Fri, 2 Dec 2011 06:12:25 -0800
> From: "Jim Thomson" <jim.thom@telus.net>
> Subject: [TowerTalk] Cost effective Tower height
> To: <towertalk@contesting.com>
> Message-ID: <CC87354A095E44198C9F5017DD5F0040@JimboPC>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Date: Thu, 01 Dec 2011 19:16:14 +0000
> From: Steve Hunt <steve@karinya.net>
> Subject: Re: [TowerTalk] Cost effectivel Tower height
>
> I think we sometimes concentrate too much on looking at antenna heights
> that will maximize gain at certain take-off angles, and forget about the
> nulls. Those deep elevation nulls can be "killers" if arrival angles
> over a wanted path happen to fall in them.
>
> So, before going firm on a height I'd encourage you to look at the ARRL
> Angle-of-Arrival statistics for various bands and paths, and make sure
> your selected height is not going to put a deep null at a high
> probability arrival angle for the bands/paths you are most interested
> in. It might be a better trade to be 1dB weak for 80% of the time rather
> than 20dB weak for 20% of the time, if you get my point.
>
> 73,
> Steve G3TXQ
>
> ## I'd agree on this. For a single height, I'd opt for 70-85' range.
> 70' is a winner every time for a single height, for a multiband 40-10m
> yagi that you propose. Back in the late 1970's here in town, we had one
> fellow with his tribander at 50'..... and another fellow with 20 m monobander
> at 100'...[ and with a 10/15 m interlaced array, 10' above the 20m yagi].
>
> ## The fellow with the 100' tall yagi would win out 85% of the time for dx to
> eu,
> but not asia, or south pacific. A lot of times the station with the 50'
> high tribander
> would clean the other fellow's clock. That happened quite often. I came
> along, with
> my 20m yagi at 72'..and the 15m yagi 8' higher. 95% of the time I was as
> loud as the
> 100' tall yagi....and at no time did the 50' tall tribander beat me out. I
> trounced the
> 50' tall array, hands down, any direction, any time of the day.
>
> ## after 2 years of this back and forth testing, my conclusion was most of
> the time, the
> angles were aprx 15 deg.... and that 10 degs was too low...and 20 deg was
> too high.
> To make matter's worse.... the fellow with the 100' high ant [10 deg
> angle] had a perfect
> NULL at 20 degs ! And of course the fellow with the 50' high tribander
> had max gain at
> 20 degs.
>
> ## Higher is better..up to a point, then you get too high, and then u have
> diminishing returns, PLUS
> you now have a big null at 20 degs. Of course if you have a motorized crank
> up, you can have
> your cake and eat it too. Since your proposed array is a 40-10m affair,
> I'd suggest 80'.
> A T-400 trylon would fit the bill, [ or the AN wireless 80', which is a lot
> stronger tower].
> Don't go cheap on the rotor, it's a one shot deal, PST-61, OR-2800,
> something big, with loads
> of TQ. Use anything smaller, and you will trash it, then you will have to
> replace with a big rotor
> anyway, so you saved...nothing.
>
> ## OK, you have neg 5 deg slope in all directions. I'd opt for 70' then.
> Like a T-500 trylon,
> or the 70' an wireless. Don't go cheap on the tower either..u want the WIDE
> base. If using the
> trylon, make it 6' deep, instead of 5 1/2'..and use a grid of re-bar across
> the top, so u have re-bar on
> 5 x sides..and use 30 mpa concrete [ 4350 psi..or at least 4000 psi]. The
> tower and the base is
> another one shot deal. In a 70+ mph wind + ice, then you can sleep at night.
> Freestanding tower's
> are a lot easier to deal with when installing any yagi..and no guys to mess
> with. By the time you
> buy the megabuck phillystran and the rohn 45, guy brackets, turnbuckles,
> loos gauge, etc,
> then install 3 x concrete guy anchor's, you will have saved nothing...or
> very little.
>
> later... Jim VE7RF
>
>
>
> ------------------------------
>
> Message: 6
> Date: Fri, 02 Dec 2011 14:59:17 +0000
> From: "K1TTT" <K1TTT@ARRL.NET>
> Subject: Re: [TowerTalk] Cost effective Tower height
> To: <towertalk@contesting.com>
> Message-ID: <003f01ccb102$f814b7a0$e83e26e0$@ARRL.NET>
> Content-Type: text/plain; charset=US-ASCII
>
> That's what stacks are for!
>
> David Robbins K1TTT
> e-mail: mailto:k1ttt@arrl.net
> web: http://wiki.k1ttt.net
> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
>
> -----Original Message-----
> From: Jim Thomson [mailto:jim.thom@telus.net]
> Sent: Friday, December 02, 2011 14:12
> To: towertalk@contesting.com
> Subject: [TowerTalk] Cost effective Tower height
>
> Date: Thu, 01 Dec 2011 19:16:14 +0000
> From: Steve Hunt <steve@karinya.net>
> Subject: Re: [TowerTalk] Cost effectivel Tower height
>
> I think we sometimes concentrate too much on looking at antenna heights that
> will maximize gain at certain take-off angles, and forget about the nulls.
> Those deep elevation nulls can be "killers" if arrival angles over a wanted
> path happen to fall in them.
>
> So, before going firm on a height I'd encourage you to look at the ARRL
> Angle-of-Arrival statistics for various bands and paths, and make sure your
> selected height is not going to put a deep null at a high probability
> arrival angle for the bands/paths you are most interested in. It might be a
> better trade to be 1dB weak for 80% of the time rather than 20dB weak for
> 20% of the time, if you get my point.
>
> 73,
> Steve G3TXQ
>
> ## I'd agree on this. For a single height, I'd opt for 70-85' range.
> 70' is a winner every time for a single height, for a multiband 40-10m yagi
> that you propose. Back in the late 1970's here in town, we had one fellow
> with his tribander at 50'..... and another fellow with 20 m monobander at
> 100'...[ and with a 10/15 m interlaced array, 10' above the 20m yagi].
>
> ## The fellow with the 100' tall yagi would win out 85% of the time for dx
> to eu,
> but not asia, or south pacific. A lot of times the station with the 50'
> high tribander
> would clean the other fellow's clock. That happened quite often. I came
> along, with
> my 20m yagi at 72'..and the 15m yagi 8' higher. 95% of the time I was as
> loud as the 100' tall yagi....and at no time did the 50' tall tribander
> beat me out. I trounced the
> 50' tall array, hands down, any direction, any time of the day.
>
> ## after 2 years of this back and forth testing, my conclusion was most of
> the time, the angles were aprx 15 deg.... and that 10 degs was too
> low...and 20 deg was too high.
> To make matter's worse.... the fellow with the 100' high ant [10 deg
> angle] had a perfect
> NULL at 20 degs ! And of course the fellow with the 50' high
> tribander had max gain at
> 20 degs.
>
> ## Higher is better..up to a point, then you get too high, and then u have
> diminishing returns, PLUS you now have a big null at 20 degs. Of course if
> you have a motorized crank up, you can have
> your cake and eat it too. Since your proposed array is a 40-10m affair,
> I'd suggest 80'.
> A T-400 trylon would fit the bill, [ or the AN wireless 80', which is a
> lot stronger tower].
> Don't go cheap on the rotor, it's a one shot deal, PST-61, OR-2800,
> something big, with loads of TQ. Use anything smaller, and you will trash
> it, then you will have to replace with a big rotor anyway, so you
> saved...nothing.
>
> ## OK, you have neg 5 deg slope in all directions. I'd opt for 70' then.
> Like a T-500 trylon, or the 70' an wireless. Don't go cheap on the tower
> either..u want the WIDE base. If using the trylon, make it 6' deep, instead
> of 5 1/2'..and use a grid of re-bar across the top, so u have re-bar on
> 5 x sides..and use 30 mpa concrete [ 4350 psi..or at least 4000 psi]. The
> tower and the base is
> another one shot deal. In a 70+ mph wind + ice, then you can sleep at night.
> Freestanding tower's are a lot easier to deal with when installing any
> yagi..and no guys to mess with. By the time you buy the megabuck
> phillystran and the rohn 45, guy brackets, turnbuckles, loos gauge, etc,
> then install 3 x concrete guy anchor's, you will have saved nothing...or
> very little.
>
> later... Jim VE7RF
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
> ------------------------------
>
> Message: 7
> Date: Fri, 2 Dec 2011 10:11:01 -0500
> From: Bert Almemo <balmemo@sympatico.ca>
> Subject: Re: [TowerTalk] cushcraft D3W
> To: "'Bill Feissner'" <ai3q@pa.metrocast.net>,
> <towertalk@contesting.com>
> Message-ID: <BLU0-SMTP77F6D429B52CC50B645D99D4B60@phx.gbl>
> Content-Type: text/plain; charset="us-ascii"
>
> Hi Bill,
>
> This topic has been discussed before and the simple answer is that you can
> mount the dipole on the same boom as the 402CD if you want. There will be
> very little or no interaction.
>
> A friend of mine put a D3W on a 10/15/20M yagi between the driven element
> and the reflector. He's had it for years and it works great. Good luck!
>
> 73 Bert, VE3NR
>
>
>
> -----Original Message-----
> From: towertalk-bounces@contesting.com
> [mailto:towertalk-bounces@contesting.com] On Behalf Of Bill Feissner
> Sent: Thursday, December 01, 2011 3:10 PM
> To: towertalk@contesting.com
> Subject: [TowerTalk] cushcraft D3W
>
> What kind of opinion s there about mounting a D3W 5 feet under a 402cd. The
> 402cd is about 5 feet above the top of the tower and can't go any higher. I
> can mount the D3W paralell to the elements or run it with the boom. I know a
> yagi would be better but I am out of tower space except for this area. I did
> at one time have a 40 rotatible dipole under a 5 el tribander running with
> the boom about 7 feet below it with no ill effects...any thoughts on this.
> thanks Bill, AI3Q _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
>
> ------------------------------
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
>
>
> End of TowerTalk Digest, Vol 108, Issue 7
> *****************************************
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