It's not the outer jacket that would be the life-limiter in this
design, but it definitely contributes to the eventual problem. Heat
absorbed by the outer conductor and also that dissipated between the
center conductor and the shield will cause distortion of the
dielectric. The coax is wound in a loop with the dielectric holding
the center conductor in place. As the dielectric softens due to the
heat, it will allow the center conductor to migrate outwards to its
more natural form (straighter, in less tension). Eventually the
center conductor will contact the shield and the trap will be
useless. This phenomenon happens faster in hot areas (i.e. the South)
than in more moderate climates, but it does happen in time over all.
OK, so this was overly technical in the discussion, but the gist is
that the dielectric will melt and the center conductor will short to
the shield. The sun will heat darker colors more than light colors,
but in time the trap will fail. Anyone have a good reference as to
how long it will take? I have seen this happen in just months in
South Florida...
On Jul 19, 2008, at 10:15 PM, Steve Davis -Davis RF Co. wrote:
> Hi Dave, not sure if I am completely qualified to answer your
> question,
> but not seeing any response, I will throw my thoughts in. I can
> only say
> that from the prospective of the outer winding of RG-213, as long
> as you are
> using an RG-213 which has a Type-IIA outer jacket
> (PVC Type IIA), which is inherently a non-migrating type, AND if it
> ALSO is
> UV resistant (not all IIA is UV resistant, but all we supply for
> outdoor is
> both IIA and UV resistant, both of which is the ONLY way to go),
> then I
> wouldn't worry at all for some 15-20 years of jacket and internal
> life of
> the cable. There is a supplier, possibly suppliers, that sell a
> PVC jacket
> for outdoors that is NOT IIA , and also they CLAIM that it is
> buriable, but
> strictly by definition, if the jacket is PVC, there is no PVC being
> used
> currently that is truly buriable (another subject) . Ref. ur sched
> 40 trap
> core, whether or not the 213 outer winding is covering all or most
> of that
> core, I wouldn't be concerned with degradation of the sched 40,
> enough to
> make any difference in the assembly/function of the trap, certainly
> for the
> life period of the coax itself (15-20 years). The wall is more
> than thick
> enough to handled any UV that might hit it for such a period.
> Having said
> all that, I haven't actually seen the configuration you
> describe...if you
> have a picture or dwg, etc I'd be glad to look at it further.
> 73, Steve
> K1PEK JS/KJ/CC
> DAVIS RF Co.
> Wire, Cable, RF Connectors and wire aerial parts. LMR, Heliax, Eupen
>
> Commercial / Military / & Custom Cable Design
>
> tel: 978-369-1738 Fax: 978-369-3484
> www.DavisRF.com
>
>
>
>
> ----- Original Message -----
> From: <towertalk-request@contesting.com>
> To: <towertalk@contesting.com>
> Sent: Saturday, July 19, 2008 3:31 PM
> Subject: TowerTalk Digest, Vol 67, Issue 64
>
>
>> Send TowerTalk mailing list submissions to
>> towertalk@contesting.com
>>
>> To subscribe or unsubscribe via the World Wide Web, visit
>> http://lists.contesting.com/mailman/listinfo/towertalk
>> or, via email, send a message with subject or body 'help' to
>> towertalk-request@contesting.com
>>
>> You can reach the person managing the list at
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>>
>> When replying, please edit your Subject line so it is more specific
>> than "Re: Contents of TowerTalk digest..."
>>
>>
>> Today's Topics:
>>
>> 1. Yagi Balun (walnutcreek@appstate.net)
>> 2. Re: Yagi Balun (Peter Voelpel)
>> 3. Re: another stupid guywire question (K5MLC (Mike))
>> 4. Fw: Tower MFG help (jody.n7ert)
>> 5. Fw: Tower MFG help (jody.n7ert)
>> 6. Fw: Tower MFG help (jody.n7ert)
>> 7. Fw: Tower MFG help (jody.n7ert)
>> 8. Painting Traps... (R. David Eagle)
>> 9. Re: Yagi Balun (Wes Attaway (N5WA))
>> 10. Long cable pull (K4SAV)
>> 11. Re: Long cable pull (John Ammeter)
>>
>>
>> ---------------------------------------------------------------------
>> -
>>
>> Message: 1
>> Date: Sat, 19 Jul 2008 12:27:47 -0400
>> From: <walnutcreek@appstate.net>
>> Subject: [TowerTalk] Yagi Balun
>> To: <towertalk@contesting.com>
>> Message-ID: <1718503415.20080719122747@appstate.net>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> I beg to differ...
>> I changed the baluns on my Telrex Monobanders, and a TB5EM to 1:1
>> Ferrite
>> Choke Baluns that I built and they are working great with a 1:1
>> SWR and a
>> max at band edge of 1.6:1 SWR. They're all down and in stroage right
>> now....moved.
>> Worked for me, just my experience.
>> 73 from afar,
>> Cam WA4JKW
>>
>>
>> I do believe that the Telrex monoband yagis employed the use of a
>> T match
>> in
>> the driven element. The impedance of a T match is not 50 ohms but
>> 400 to
>> 600 ohms. You would probably need a 9:1 Balun. A 1:1 Balun will not
>> work.
>>
>> Bob W6TR
>>
>>
>>> Three 29 year old TELREX MONOBAND yagi's are off the towers and
>>> on the
>>> ground for maintenance and repairs. The factory made and
>>> installed coax
>>> baluns will be replaced. If the baluns are replaced with a
>>> ferrite-bead
>>> type 1:1 balun such as the Force-12 brand, will the antenna
>>> pattern or
>>> other factors be changed?
>>>
>>> Thanks.
>>>
>>> Bee K4JLD
>>> k4jld@juno.com
>>> __________________________________________________________
>>
>>
>>
>> ------------------------------
>>
>> Message: 2
>> Date: Sat, 19 Jul 2008 19:06:36 +0200
>> From: "Peter Voelpel" <df3kv@t-online.de>
>> Subject: Re: [TowerTalk] Yagi Balun
>> To: <towertalk@contesting.com>
>> Message-ID: <15D89687D24A408CA7130F6125518605@ap200>
>> Content-Type: text/plain; charset="us-ascii"
>>
>> Typically with a t-match the matching arms are adjusted for an
>> impedance
>> of
>> 200 ohms and then a halfwave coax 4:1 transformer is used for
>> matching to
>> 50
>> ohms unbalanced feedline.
>>
>> 73
>> Peter
>>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] On Behalf Of Bob Maser
>> Sent: Samstag, 19. Juli 2008 04:09
>> To: towertalk@contesting.com; Bee Walton
>> Subject: Re: [TowerTalk] Yagi Balun
>>
>> I do believe that the Telrex monoband yagis employed the use of a
>> T match
>> in
>> the driven element. The impedance of a T match is not 50 ohms but
>> 400 to
>> 600 ohms. You would probably need a 9:1 Balun. A 1:1 Balun will not
>> work.
>>
>> Bob W6TR
>> ----- Original Message -----
>> From: "Bee Walton" <k4jld@juno.com>
>> To: <towertalk@contesting.com>
>> Sent: Friday, July 18, 2008 6:24 PM
>> Subject: [TowerTalk] Yagi Balun
>>
>>
>>> Three 29 year old TELREX MONOBAND yagi's are off the towers and
>>> on the
>>> ground for maintenance and repairs. The factory made and
>>> installed coax
>>> baluns will be replaced. If the baluns are replaced with a
>>> ferrite-bead
>>> type 1:1 balun such as the Force-12 brand, will the antenna
>>> pattern or
>>> other factors be changed?
>>>
>>> Thanks.
>>>
>>> Bee K4JLD
>>> k4jld@juno.com
>>> ____________________________________________________________
>>> Need cash? Click to get a cash advance.
>>>
>> http://thirdpartyoffers.juno.com/TGL2141/fc/
>> Ioyw6i3mKeticKh9mZBzKeQwXuyJWoov
>> M4PBqFzJWojut7VXNbYh9C/
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> 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
>>
>>
>>
>> ------------------------------
>>
>> Message: 3
>> Date: Sat, 19 Jul 2008 10:10:27 -0700 (PDT)
>> From: "K5MLC \(Mike\)" <k5mlc@sbcglobal.net>
>> Subject: Re: [TowerTalk] another stupid guywire question
>> To: "Michael Fox \(K5MEF\)" <k5mef@mefox.org>
>> Cc: towertalk <towertalk@contesting.com>
>> Message-ID: <862535.94925.qm@web81907.mail.mud.yahoo.com>
>> Content-Type: text/plain; charset=iso-8859-1
>>
>> Very good question.? In my case, Michael, I just want something
>> with high
>> tensile strength?that is comparable with EHS specifications and I
>> found
>> that I could get the galvanized "aircraft cable" with the same
>> tensile
>> strength for about 2/3 of the cost of EHS. Yes, the Phillistrand
>> would be
>> an excellent alternative if I wanted?and had the extra cash to
>> spend. I've
>> researched?Rohn 25 tower guying specifications on the Rohn site and
>> made?my guying decisions based on that.?
>> OTOH, I live in an area that is subject to high winds from tropical
>> disturbances so I want to try to support the tower as much as I
>> can within
>> financial reason and good common sense.?I don't think guywire with
>> higher
>> tensile strength than EHS would have any benefit for me with a 51'
>> tower.?If we get a really big blow, survivability of the tower is in
>> question -?chances are the tower is going to come down. I plan on
>> insuring
>> it and the rest of my equipment through the insurance plan with
>> the ARRL.
>> End of story. ?
>> 73 de K5MLC
>> Mike
>>
>> ----- Original Message ----
>> From: Michael Fox (K5MEF) <k5mef@mefox.org>
>> To: towertalk@contesting.com
>> Sent: Friday, July 18, 2008 5:02:47 PM
>> Subject: Re: [TowerTalk] another stupid guywire question
>>
>> I've been following the discussion about guy wires with great
>> interest.?
>> The
>> Phillystrand product is also very interesting.
>>
>> Please excuse my ignorance.? How does one go about determining which
>> tensile
>> strength of Phillystrand (or any other material) is needed for a
>> particular
>> application?
>>
>> Michael K5MEF
>>
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>>
>> ------------------------------
>>
>> Message: 4
>> Date: Sat, 19 Jul 2008 10:10:01 -0700
>> From: "jody.n7ert" <jody.n7ert@gmail.com>
>> Subject: [TowerTalk] Fw: Tower MFG help
>> To: <towertalk@contesting.com>
>> Message-ID: <000401c8e9c2$64225d00$d200a8c0@EchoTest>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Anyone seen this tower?? Seeking help to identify the fabricator
>> of a
>> tower.. I appears not to be Valmont/Pirod, ERI, or Radian/Rohn. Each
>> section is bolted together with 6 ea 10" long 1" bolts, 2 per
>> leg... Top
>> section is marked with number 332142-2 and bottom section is
>> marked with
>> 332142-1,which has a 4 bolt flanges that mounts it to the concrete
>> tower
>> base 8'x8'x6'.. Face on tower is approx 36", Tower leg is 2"
>> solid rod.
>> Attached is link to picture that shows the metal ID tag and one
>> mounting
>> bolt section
>> Thanks, Jody N7ERT http://www.orednet.org/~jcross/tower1.jpg
>>
>>
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 5
>> Date: Sat, 19 Jul 2008 10:10:56 -0700
>> From: "jody.n7ert" <jody.n7ert@gmail.com>
>> Subject: [TowerTalk] Fw: Tower MFG help
>> To: <towertalk@contesting.com>
>> Message-ID: <000b01c8e9c2$6b496b00$d200a8c0@EchoTest>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Anyone seen this tower?? Seeking help to identify the fabricator
>> of a
>> tower.. I appears not to be Valmont/Pirod, ERI, or Radian/Rohn. Each
>> section is bolted together with 6 ea 10" long 1" bolts, 2 per
>> leg... Top
>> section is marked with number 332142-2 and bottom section is
>> marked with
>> 332142-1,which has a 4 bolt flanges that mounts it to the concrete
>> tower
>> base 8'x8'x6'.. Face on tower is approx 36", Tower leg is 2"
>> solid rod.
>> Attached is link to picture that shows the metal ID tag and one
>> mounting
>> bolt section
>> Thanks, Jody N7ERT http://www.orednet.org/~jcross/tower1.jpg
>>
>>
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 6
>> Date: Sat, 19 Jul 2008 10:11:10 -0700
>> From: "jody.n7ert" <jody.n7ert@gmail.com>
>> Subject: [TowerTalk] Fw: Tower MFG help
>> To: <towertalk@contesting.com>
>> Message-ID: <001201c8e9c2$73937530$d200a8c0@EchoTest>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Anyone seen this tower?? Seeking help to identify the fabricator
>> of a
>> tower.. I appears not to be Valmont/Pirod, ERI, or Radian/Rohn. Each
>> section is bolted together with 6 ea 10" long 1" bolts, 2 per
>> leg... Top
>> section is marked with number 332142-2 and bottom section is
>> marked with
>> 332142-1,which has a 4 bolt flanges that mounts it to the concrete
>> tower
>> base 8'x8'x6'.. Face on tower is approx 36", Tower leg is 2"
>> solid rod.
>> Attached is link to picture that shows the metal ID tag and one
>> mounting
>> bolt section
>> Thanks, Jody N7ERT http://www.orednet.org/~jcross/tower1.jpg
>>
>>
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 7
>> Date: Sat, 19 Jul 2008 10:12:50 -0700
>> From: "jody.n7ert" <jody.n7ert@gmail.com>
>> Subject: [TowerTalk] Fw: Tower MFG help
>> To: <towertalk@contesting.com>
>> Message-ID: <000c01c8e9c2$ae639c30$d200a8c0@EchoTest>
>> Content-Type: text/plain; charset="iso-8859-1"
>>
>> Anyone seen this tower?? Seeking help to identify the fabricator
>> of a
>> tower.. I appears not to be Valmont/Pirod, ERI, or Radian/Rohn. Each
>> section is bolted together with 6 ea 10" long 1" bolts, 2 per
>> leg... Top
>> section is marked with number 332142-2 and bottom section is
>> marked with
>> 332142-1,which has a 4 bolt flanges that mounts it to the concrete
>> tower
>> base 8'x8'x6'.. Face on tower is approx 36", Tower leg is 2"
>> solid rod.
>> Attached is link to picture that shows the metal ID tag and one
>> mounting
>> bolt section
>> Thanks, Jody N7ERT http://www.orednet.org/~jcross/tower1.jpg
>>
>>
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 8
>> Date: Sat, 19 Jul 2008 12:13:24 -0700 (PDT)
>> From: "R. David Eagle" <kb8nnu@yahoo.com>
>> Subject: [TowerTalk] Painting Traps...
>> To: Tower Talk List <towertalk@contesting.com>
>> Message-ID: <963807.55399.qm@web51706.mail.re2.yahoo.com>
>> Content-Type: text/plain; charset=iso-8859-1
>>
>> Hello all...
>> I am in the process of putting a Battle Creek Special (trapper edt.)
>> together and was wondering if I should paint the traps since they
>> will be
>> exposed to UV.? The traps are made out of 4'' PVC drain pipe and
>> is wound
>> with rg-213.? Will painting the traps affect the performance of
>> the traps
>> or should I not worry about it?
>> Thanks,
>> Dave
>> KB8NNU
>>
>>
>>
>>
>> ------------------------------
>>
>> Message: 9
>> Date: Sat, 19 Jul 2008 14:38:37 -0500
>> From: "Wes Attaway \(N5WA\)" <wesattaway@bellsouth.net>
>> Subject: Re: [TowerTalk] Yagi Balun
>> To: <walnutcreek@appstate.net>, <towertalk@contesting.com>
>> Message-ID: <65A63AB7F3E344D7831A9D34B8E490B1@OFFICE>
>> Content-Type: text/plain; charset="us-ascii"
>>
>> My 5-el Telrex 20M beam used a 4:1 transformer. I no longer have
>> that
>> antenna but I do know that was what it used.
>>
>> ------------------ Wes Attaway (N5WA) ------------------
>> 1138 Waters Edge Circle - Shreveport, LA 71106
>> 318-797-4972 (office) - 318-393-3289 (cell)
>> Computer Consulting and Forensics
>> -------------- EnCase Certified Examiner ---------------
>>
>> -----Original Message-----
>> From: towertalk-bounces@contesting.com
>> [mailto:towertalk-bounces@contesting.com] On Behalf Of
>> walnutcreek@appstate.net
>> Sent: Saturday, July 19, 2008 11:28 AM
>> To: towertalk@contesting.com
>> Subject: [TowerTalk] Yagi Balun
>>
>> I beg to differ...
>> I changed the baluns on my Telrex Monobanders, and a TB5EM to 1:1
>> Ferrite
>> Choke Baluns that I built and they are working great with a 1:1
>> SWR and a
>> max at band edge of 1.6:1 SWR. They're all down and in stroage right
>> now....moved.
>> Worked for me, just my experience.
>> 73 from afar,
>> Cam WA4JKW
>>
>>
>> I do believe that the Telrex monoband yagis employed the use of a
>> T match
>> in
>>
>> the driven element. The impedance of a T match is not 50 ohms but
>> 400 to
>> 600 ohms. You would probably need a 9:1 Balun. A 1:1 Balun will not
>> work.
>>
>> Bob W6TR
>>
>>
>>> Three 29 year old TELREX MONOBAND yagi's are off the towers and
>>> on the
>>> ground for maintenance and repairs. The factory made and
>>> installed coax
>>> baluns will be replaced. If the baluns are replaced with a
>>> ferrite-bead
>>> type 1:1 balun such as the Force-12 brand, will the antenna
>>> pattern or
>>> other factors be changed?
>>>
>>> Thanks.
>>>
>>> Bee K4JLD
>>> k4jld@juno.com
>>> __________________________________________________________
>>
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>>
>>
>> ------------------------------
>>
>> Message: 10
>> Date: Sat, 19 Jul 2008 17:13:53 -0500
>> From: K4SAV <RadioIR@charter.net>
>> Subject: [TowerTalk] Long cable pull
>> To: towertalk@contesting.com
>> Message-ID: <48826721.2060703@charter.net>
>> Content-Type: text/plain; charset=us-ascii; format=flowed
>>
>> After being disappointed in the direct burial method, I am
>> planning on
>> adding some conduit to access my low band receiving antennas. I have
>> one section of conduit that is 500 feet. Can I do this with one
>> pull,
>> or will I be wishing a I had added an access box and broken the
>> pull up
>> into two parts? I have never pulled a 500 ft run before. Since it is
>> unlikely that I will ever want to add another cable into this
>> conduit, I
>> was planning on using 1.5 inch conduit. The run will be straight
>> except
>> for a couple of very long curves and then the curve at the exit
>> out of
>> the ground at the ends. I need to pull one run of RG6 and one run
>> of 16
>> ga landscape lightning cable for dc.
>>
>> Before someone suggests sending the dc down the RG6 to eliminate a
>> cable, the dc resistance of 635 ft of RG6 is about 22 ohms. (It's
>> 625
>> ft total to get to the operating position.) Besides the RG6
>> already has
>> dc controls signals on it as well as RF.
>>
>> Second question: What is a good method of putting the pull string
>> in a
>> conduit this long? I have put it there when building the conduit,
>> but
>> that is a pain. I have used an air compressor to blow a string
>> tied to
>> a rag thru the conduit, but never on a conduit this long. Is that
>> likely to work?
>>
>> Jerry, K4SAV
>>
>>
>> ------------------------------
>>
>> Message: 11
>> Date: Sat, 19 Jul 2008 15:31:17 -0700
>> From: John Ammeter <jammeter@cablespeed.com>
>> Subject: Re: [TowerTalk] Long cable pull
>> To: K4SAV <RadioIR@charter.net>
>> Cc: towertalk@contesting.com
>> Message-ID: <48826B35.2080507@cablespeed.com>
>> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>>
>> You can probably use a "mouse" and a shop vacuum to get the first
>> lightweight pull string down the conduit. Use the lightweight
>> string to
>> pull a stronger pull rope. I've never pulled 500 feet but with
>> virtually a straight run I doubt you'll have any trouble. I'm not
>> sure
>> if pulling grease is compatible with RG6 and you probably won't
>> need it
>> anyway.
>>
>> I used 1 1/2" conduit to run 4 10 gauge conductors with two sharp
>> 90's
>> and one gradual 90 bend over 100 feet with no trouble. Also, 3 12
>> gauge
>> solid conductors 125 feet through a 3/4" conduit with two 90's.
>> Didn't
>> use any pulling grease...
>>
>> John KE7JGB
>>
>> K4SAV wrote:
>>> After being disappointed in the direct burial method, I am
>>> planning on
>>> adding some conduit to access my low band receiving antennas. I
>>> have
>>> one section of conduit that is 500 feet. Can I do this with one
>>> pull,
>>> or will I be wishing a I had added an access box and broken the
>>> pull up
>>> into two parts? I have never pulled a 500 ft run before. Since
>>> it is
>>> unlikely that I will ever want to add another cable into this
>>> conduit, I
>>> was planning on using 1.5 inch conduit. The run will be straight
>>> except
>>> for a couple of very long curves and then the curve at the exit
>>> out of
>>> the ground at the ends. I need to pull one run of RG6 and one
>>> run of 16
>>> ga landscape lightning cable for dc.
>>>
>>> Before someone suggests sending the dc down the RG6 to eliminate a
>>> cable, the dc resistance of 635 ft of RG6 is about 22 ohms.
>>> (It's 625
>>> ft total to get to the operating position.) Besides the RG6
>>> already has
>>> dc controls signals on it as well as RF.
>>>
>>> Second question: What is a good method of putting the pull string
>>> in a
>>> conduit this long? I have put it there when building the
>>> conduit, but
>>> that is a pain. I have used an air compressor to blow a string
>>> tied to
>>> a rag thru the conduit, but never on a conduit this long. Is that
>>> likely to work?
>>>
>>> Jerry, K4SAV
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> 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 67, Issue 64
>> *****************************************
>>
>>
>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk@contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk
- Jack Brindle, W6FB
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