[TowerTalk] Re: TowerTalk Digest, Vol 8, Issue 77

[Warren Munro]

on 8/19/03 10:28 AM, towertalk-request at contesting.com at
towertalk-request at contesting.com wrote:

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> 
> Today's Topics:
> 
> 1. Brake wedges for Tailtwister (Tree)
> 2. MA type towers (Terry Dunlap)
> 3. Re: Need info & manual on 20 meter beam (AA6DX)
> 4. Re: Towers on Rock Ledge (Geoff)
> 5. Re: MA type towers
> 6. AEA HF Analyst Manual?
> (Mandell, Thomas W (N-Superior Technical Resources Inc.))
> 7. Re: W0IYH Feed line Choke Performance (Tim Duffy K3LR)
> 8. Re: W0IYH Feed line Choke Performance (Tim Duffy K3LR)
> 9. Re: W0IYH Feed line Choke Performance (Jim White, K4OJ)
> 10. RE: W0IYH Feed line Choke Performance (Joe Subich, K4IK)
> 
> 
> ----------------------------------------------------------------------
> 
> Date: Tue, 19 Aug 2003 11:39:18 -0500
> From: Tree <tree at kkn.net>
> To: towertalk at contesting.com
> Subject: [TowerTalk] Brake wedges for Tailtwister
> Message-ID: <20030819163917.GA11116 at kkn.net>
> Content-Type: text/plain; charset=us-ascii
> MIME-Version: 1.0
> Precedence: list
> Message: 1
> 
> 
> I bought a couple of brake wedges at Dayton from the HyGain booth.  I have
> to replace the one in my Tailtwister that has a 3 element 40 on it after
> most any storm (which happens about once every two years).  I noticed
> that the slot that is drilled in the middle was slightly off - about 150
> mils or so.  I put it together, but it isn't locking down.
> 
> I have asked HyGain about this and really not received much useful
> information about it.  I have now ordered a new one and hopefully it
> will have the correct dimensions, and I will send the other ones back.
> 
> Anyone else have this problem?
> 
> Tree N6TR
> tree at kkn.net
> ------------------------------
> 
> Date: Tue, 19 Aug 2003 09:29:25 -0700
> From: Terry Dunlap <kk6t at pacbell.net>
> To: towertalk at contesting.com
> Subject: [TowerTalk] MA type towers
> Message-ID: <5.1.0.14.2.20030819092919.0411bb08 at postoffice.pacbell.net>
> Content-Type: text/plain; charset="us-ascii"; format=flowed
> MIME-Version: 1.0
> Precedence: list
> Message: 2
> 
> While we're on the subject of MA type towers.......
> 
> With the rotor at the top and any mast being held by only the
> top clamp of the rotor, how can people be using 5'-10' masts?
> 
> Even with minimal loads on the top of these masts, I would think
> that would be a huge strain on the rotor clamp.
> 
> 73 de Terry KK6T 
> 
> ------------------------------
> 
> Date: Tue, 19 Aug 2003 10:02:13 -0700
> From: "AA6DX" <aa6dx at pacbell.net>
> To: "Arne Gjerning" <gjerning at flash.net>, "Bob Nielsen" <nielsen at oz.net>,
> <towertalk at contesting.com>, "Pete Smith" <n4zr at contesting.com>
> Subject: Re: [TowerTalk] Need info & manual on 20 meter beam
> Message-ID: <037801c36673$a2d3d650$7662ce3f at desk>
> References: <000e01c36599$b3c8f880$3042f60c at attbi.com>
> <20030819034827.GA10084 at n7xy.net>
> <5.2.0.9.2.20030819030057.01b788d0 at mail.adelphia.net>
> Content-Type: text/plain;
> charset="iso-8859-1"
> MIME-Version: 1.0
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> Precedence: list
> Message: 3
> 
> Bob, NA6T, and I, have the 15M version of the original LONG JOHN ... it is a
> MONDO beam!
> Unfortunately, it is stored in the horizontally grounded position .. Boy,
> did it play at my Redding, CA  contest station in the late 70s.  73, Y'all
> Mark  AA6DX
> ----- Original Message -----
> From: "Pete Smith" <n4zr at contesting.com>
> To: "Arne Gjerning" <gjerning at flash.net>; "Bob Nielsen" <nielsen at oz.net>;
> <towertalk at contesting.com>
> Sent: Tuesday, August 19, 2003 12:01 AM
> Subject: Re: [TowerTalk] Need info & manual on 20 meter beam
> 
> 
>> At 11:01 PM 8/18/03 -0600, Arne Gjerning wrote:
>>> The LJ-205CA is NOT anywhere near the same antenna.  What Chuck, N6PSN,
> has
>>> is the ORIGINAL LONG JOHN series 20M yagi from late 50s/early 60s.  He
>>> described the yagi correctly as having a 46 ft boom; whereas the LJ-205CA
>>> has ONLY a 34ft boom.  His antenna is built like a "MACK TRUCK" compared
> to
>>> the LJ-205CA.
> 
> 
> ------------------------------
> 
> Date: Tue, 19 Aug 2003 13:29:11 -0400
> From: "Geoff" <geoffrey at jeremy.mv.com>
> To: "Martin Ewing AA6E" <aa6e at arrl.net>, <towertalk at contesting.com>
> Subject: Re: [TowerTalk] Towers on Rock Ledge
> Message-ID: <024001c36677$75cb3960$6501a8c0 at Carl>
> References: <3F41042A.5020003 at arrl.net>
> Content-Type: text/plain;
> charset="iso-8859-1"
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> Message: 4
> 
> I dug down to the ledge and then had 2" diameter holes drilled down 8' at
> the guy angle.
> Installed power company rock anchors, locked in place and filled the rest of
> the hole with "Pour Rock" to seal.
> That was 11 years ago and no problems whatsoever with a total of 4 towers.
> 
> The anchors are 3/4" diameter with heavy galvanizing; easy to attach Rohn 3
> and 5 level equalizing plates.
> 
> G
> 
> 
> ----- Original Message -----
> From: "Martin Ewing AA6E" <aa6e at arrl.net>
> To: <towertalk at contesting.com>
> Sent: Monday, August 18, 2003 12:51 PM
> Subject: [TowerTalk] Towers on Rock Ledge
> 
> 
>> Folks,
>> 
>> Is there any general information available on siting towers on rock?  I
> have
>> granite ledge just a foot or less down, so digging the big hole in the
> ground
>> won't do the trick here.
>> 
>> I suppose one needs "local engineering", but maybe there is some design
> info to
>> help get me oriented.
>> 
>> Tnx / 73,  Martin, AA6E
>> 
>> _______________________________________________
>> 
>> 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 at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
> 
> 
> ------------------------------
> 
> Date: Tue, 19 Aug 2003 13:35:40 EDT
> From: K7LXC at aol.com
> To: kk6t at pacbell.net, towertalk at contesting.com
> Subject: Re: [TowerTalk] MA type towers
> Message-ID: <ae.4605bb1e.2c73b9ec at aol.com>
> Content-Type: text/plain; charset="US-ASCII"
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7bit
> Precedence: list
> Message: 5
> 
> In a message dated 8/19/03 9:33:31 AM Pacific Daylight Time, kk6t at pacbell.net
> writes:
> 
>> With the rotor at the top and any mast being held by only the
>> top clamp of the rotor, how can people be using 5'-10' masts?
> 
> There are 2 configurations: 1) rotator on the top of the tower and 2)
> rotator at the bottom of the tower as part of the MARB rotating tower system.
> It's obviously easier with the rotator at the bottom to have a loaded mast.
>> 
>> Even with minimal loads on the top of these masts, I would think
>> that would be a huge strain on the rotor clamp.
> 
> Well, yes but sometimes the rotator will take it. When I was at Hy-Gain
> in the 90's we destruction tested a TailTwister and the force required was
> something like 3,000 foot/pounds before the neck broke off. Pretty strong!
> 
> Cheers,
> Steve     K7LXC
> TOWER TECH 
> ------------------------------
> 
> Date: Tue, 19 Aug 2003 10:49:31 -0400
> From: "Mandell, Thomas W (N-Superior Technical Resources Inc.)"
> <thomas.w.mandell at lmco.com>
> To: towertalk at contesting.com
> Subject: [TowerTalk] AEA HF Analyst Manual?
> Message-ID: <F74C419E9D6FCD448BE5B4DDF904ED78047B109D at EMSS04M06.us.lmco.com>
> Content-Type: text/plain; charset=iso-8859-1
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7BIT
> Precedence: list
> Message: 6
> 
> If your looking for the AEA CIA HF analyzer manual it's available on  the AEA
> web site.
> 
> Tom W3FRG
> ------------------------------
> 
> Date: Mon, 18 Aug 2003 18:09:06 -0500
> From: Tim Duffy K3LR <k3lr at k3lr.com>
> To: "Paul Christensen, Esq." <w9ac at arrl.net>,
> Towertalk <towertalk at contesting.com>
> Subject: Re: [TowerTalk] W0IYH Feed line Choke Performance
> Message-ID: <3F415C92.E09543D6 at k3lr.com>
> References: <3F410FD4.186A29FC at k3lr.com>
> <009501c365c7$1116a5a0$6401a8c0 at se1.client2.attbi.com>
> Content-Type: text/plain; charset=us-ascii
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7bit
> Precedence: list
> Message: 7
> 
> HI Paul!
> 
> You are correct, it would be interesting experiment and some day I will take
> my
> own measurements on coax single layer chokes and I will post my findings here.
> However, in the mean time there are two excellent sources that have good
> information on the subject. W7EL has some suggested single layer coax chokes
> in
> the ARRL Antenna Book. WA2SRQ had a TowerTalk post some years back (should be
> in the archives) where Ed gave a very detailed account of his tests related to
> coax chokes.
> 
> 73,
> Tim K3LR
> http://www.k3lr.com
> 
> "Paul Christensen, Esq." wrote:
> 
>> Tim,
>> 
>> By chance, did you happen to measure the impedance of an air-wound choke
>> consisting of many tight turns?  On the low bands, it would be an
>> interesting exercise to determine the equivalent number of air-wound turns
>> needed on a given diameter in order to approximate the same impedance
>> effectiveness as either the W2DU or W0IYH types.
>> 
>> -Paul, W9AC
>> 
>> ----- Original Message -----
>> From: "Tim Duffy K3LR" <k3lr at k3lr.com>
>> To: "Towertalk" <towertalk at contesting.com>
>> Sent: Monday, August 18, 2003 1:41 PM
>> Subject: [TowerTalk] W0IYH Feed line Choke Performance
>> 
>>> I posted some of my experience concerning the W2DU type choke
>>> performance a few weeks ago.
>>> There were several requests for the test data.
>>> I retrieved my lab notes taken from my HP Network Analyzer on October
>>> 15, 2001.
>>> 
>>> The W0IYH choke is made from 100 type FB-5622-43 beads on RG-142 with
>>> silver plated PL-259's on each end.
>>> The list is test frequency followed by impedance
>>> 1.8 MHz  1152 ohms
>>> 3.7 MHz  3483 ohms
>>> 7.1 MHz  4115 ohms
>>> 14.2 MHz  1783 ohms
>>> 21.2 MHz  1280 ohms
>>> 28.5 MHz  1234 ohms
>>> 
>>> My tests with the W2DU choke:
>>> 1.8 MHz  984 ohms
>>> 3.7 MHz  1733 ohms
>>> 7.1 MHz  1921 ohms
>>> 14.2 MHz  1432 ohms
>>> 21.2 MHz  905 ohms
>>> 28.5 MHZ  423 ohms
>>> 
>>> In 100% key down CW tests into a 50 ohm dummy load for 10 minutes I
>>> found the W2DU to overheat (individual bead temperature exceeded
>>> manufactures ratings) at 500 watts on every band. The W0IYH choke passed
>>> the same test at 2000 watts and was well within the temperature
>>> specification for each bead. I believe the W0IYH choke has adequate
>>> safety factor for 1500 watt stations as long as the VSWR does not exceed
>>> 3:1.
>>> 
>>> There are lots of W2DU chokes in service and as you can see they will
>>> work well. The W0IYH design is an improved version. As I indicated in my
>>> September 1998 CQ Contest magazine article, I use the W0IYH design at my
>>> station. They are on every feed point of every antenna, at the tower
>>> mounted stacked antenna RF  switch box and at the end of each antenna
>>> feed line where it connects to the RF amplifier in the radio room. They
>>> keep RF from flowing on the outside shields of the feed lines very well.
>>> 
>>> 
>>> 
>>> If you are interested in ready to go chokes, completed W0IYH chokes are
>>> available from Comtek Systems. Please contact them for price and
>>> availability.
>>> http://www.comteksystems.com
>>> 
>>> 
>>> 73,
>>> Tim K3LR
>>> http://www.k3lr.com
>>> 
>>> 
>>> _______________________________________________
>>> 
>>> 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 at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
> 
> 
> 
> ------------------------------
> 
> Date: Mon, 18 Aug 2003 18:12:41 -0500
> From: Tim Duffy K3LR <k3lr at k3lr.com>
> To: K3vw at aol.com, Towertalk <towertalk at contesting.com>
> Subject: Re: [TowerTalk] W0IYH Feed line Choke Performance
> Message-ID: <3F415D69.BB2CDA98 at k3lr.com>
> References: <108.25e39718.2c7292e6 at aol.com>
> Content-Type: text/plain; charset=us-ascii
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7bit
> Precedence: list
> Message: 8
> 
> Hi Willy!
> 
> Jim may have not had time to post the new information. Give him a call at
> 704-542-4808. Jim's up early, so anytime after 7 AM eastern time.
> 
> 73,
> Tim K3LR
> http://www.k3lr.com
> 
> K3vw at aol.com wrote:
> 
>> Tim, I went to their site but there was W0iyh Balun there, just W2DU types.
>> Did I miss something?  I've been building my own baluns and 9: to 1 beverage
>> impedence transformers for over 22 years now. Some of the big gun's on 160
>> still
>> have mine in use after all that time & RF!!  Willy K3VW
> 
> 
> 
> ------------------------------
> 
> Date: Tue, 19 Aug 2003 15:03:15 -0400
> From: "Jim White, K4OJ" <k4oj at tampabay.rr.com>
> To: Tim Duffy K3LR <k3lr at k3lr.com>
> Cc: Towertalk <towertalk at contesting.com>
> Cc: "Paul Christensen, Esq." <w9ac at arrl.net>
> Subject: Re: [TowerTalk] W0IYH Feed line Choke Performance
> Message-ID: <3F427473.2010802 at tampabay.rr.com>
> References: <3F410FD4.186A29FC at k3lr.com>
> <009501c365c7$1116a5a0$6401a8c0 at se1.client2.attbi.com>
> <3F415C92.E09543D6 at k3lr.com>
> Content-Type: text/plain; charset=us-ascii; format=flowed
> MIME-Version: 1.0
> Content-Transfer-Encoding: 7bit
> Precedence: list
> Reply-To: k4oj at tampabay.rr.com
> Message: 9
> 
> ...the WA2SRQ studies are on several places on the net including K1TTT's
> most excellent web site
> 
> http://www.k1ttt.net/technote/airbalun.html
> 
> I have toyed with the idea of making these as a side business... as a
> happy user of "WA2SRQ baluns" for years... and no bugs!
> 
> I would be interested to know if there is a market for these... I am
> looking for a small business, have a few mechanical tweaks W1CW and I
> added to the basic design - probably would sell them on eBay or in the
> ham classifieds...
> 
> Please reply direct to me on this one!
> 
> Thanks,
> 
> Jim, K4OJ
> 
> 
> 
> 
> Tim Duffy K3LR wrote:
>> HI Paul!
>> 
>> You are correct, it would be interesting experiment and some day I will take
>> my
>> own measurements on coax single layer chokes and I will post my findings
>> here.
>> However, in the mean time there are two excellent sources that have good
>> information on the subject. W7EL has some suggested single layer coax chokes
>> in
>> the ARRL Antenna Book. WA2SRQ had a TowerTalk post some years back (should be
>> in the archives) where Ed gave a very detailed account of his tests related
>> to
>> coax chokes.
>> 
>> 73,
>> Tim K3LR
>> http://www.k3lr.com
>> 
>> "Paul Christensen, Esq." wrote:
>> 
>> 
>>> Tim,
>>> 
>>> By chance, did you happen to measure the impedance of an air-wound choke
>>> consisting of many tight turns?  On the low bands, it would be an
>>> interesting exercise to determine the equivalent number of air-wound turns
>>> needed on a given diameter in order to approximate the same impedance
>>> effectiveness as either the W2DU or W0IYH types.
>>> 
>>> -Paul, W9AC
>>> 
>>> ----- Original Message -----
>>> From: "Tim Duffy K3LR" <k3lr at k3lr.com>
>>> To: "Towertalk" <towertalk at contesting.com>
>>> Sent: Monday, August 18, 2003 1:41 PM
>>> Subject: [TowerTalk] W0IYH Feed line Choke Performance
>>> 
>>> 
>>>> I posted some of my experience concerning the W2DU type choke
>>>> performance a few weeks ago.
>>>> There were several requests for the test data.
>>>> I retrieved my lab notes taken from my HP Network Analyzer on October
>>>> 15, 2001.
>>>> 
>>>> The W0IYH choke is made from 100 type FB-5622-43 beads on RG-142 with
>>>> silver plated PL-259's on each end.
>>>> The list is test frequency followed by impedance
>>>> 1.8 MHz  1152 ohms
>>>> 3.7 MHz  3483 ohms
>>>> 7.1 MHz  4115 ohms
>>>> 14.2 MHz  1783 ohms
>>>> 21.2 MHz  1280 ohms
>>>> 28.5 MHz  1234 ohms
>>>> 
>>>> My tests with the W2DU choke:
>>>> 1.8 MHz  984 ohms
>>>> 3.7 MHz  1733 ohms
>>>> 7.1 MHz  1921 ohms
>>>> 14.2 MHz  1432 ohms
>>>> 21.2 MHz  905 ohms
>>>> 28.5 MHZ  423 ohms
>>>> 
>>>> In 100% key down CW tests into a 50 ohm dummy load for 10 minutes I
>>>> found the W2DU to overheat (individual bead temperature exceeded
>>>> manufactures ratings) at 500 watts on every band. The W0IYH choke passed
>>>> the same test at 2000 watts and was well within the temperature
>>>> specification for each bead. I believe the W0IYH choke has adequate
>>>> safety factor for 1500 watt stations as long as the VSWR does not exceed
>>>> 3:1.
>>>> 
>>>> There are lots of W2DU chokes in service and as you can see they will
>>>> work well. The W0IYH design is an improved version. As I indicated in my
>>>> September 1998 CQ Contest magazine article, I use the W0IYH design at my
>>>> station. They are on every feed point of every antenna, at the tower
>>>> mounted stacked antenna RF  switch box and at the end of each antenna
>>>> feed line where it connects to the RF amplifier in the radio room. They
>>>> keep RF from flowing on the outside shields of the feed lines very well.
>>>> 
>>>> 
>>>> 
>>>> If you are interested in ready to go chokes, completed W0IYH chokes are
>>>> available from Comtek Systems. Please contact them for price and
>>>> availability.
>>>> http://www.comteksystems.com
>>>> 
>>>> 
>>>> 73,
>>>> Tim K3LR
>>>> http://www.k3lr.com
>>>> 
>>>> 
>>>> _______________________________________________
>>>> 
>>>> 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 at contesting.com
>>>> http://lists.contesting.com/mailman/listinfo/towertalk
>>> 
>> 
>> 
>> 
>> _______________________________________________
>> 
>> 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 at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>> 
> 
> 
> 
> ------------------------------
> 
> Date: Tue, 19 Aug 2003 15:20:04 -0400
> From: "Joe Subich, K4IK" <k4ik at subich.com>
> To: "'Tim Duffy K3LR'" <k3lr at k3lr.com>,
> "'Towertalk'" <towertalk at contesting.com>
> Subject: RE: [TowerTalk] W0IYH Feed line Choke Performance
> Message-ID: <002a01c36686$e56d4420$c080a8c0 at laptop>
> In-Reply-To: <3F415C92.E09543D6 at k3lr.com>
> Content-Type: text/plain;
> charset="us-ascii"
> MIME-Version: 1.0
> Content-Transfer-Encoding: 8bit
> Precedence: list
> Message: 10
> 
> 
> Here is the WA2SRQ data from my personal archive ...
> 
> ---------------------------------------------------------------------
> 
> Having access to a Hewlett-Packard 4193A vector impedance meter at work,
> I have made measurements on a number of baluns, coaxial and otherwise.
> For my beams I was particularly interested how many turns and on what
> diameter are optimum for air core coaxial baluns, and what the effect of
> bunching the turns was (formless).  Using the remote programming capability
> of the HP4193A along with an instrument controller, I measured the magnitude
> 
> and phase of each balun's winding impedance at 1 MHz intervals from 1 to 35
> MHz.  For comparison, I also made measurements on a commercial balun which
> consists of a number of ferrite beads slipped over a short length of coax.
> I've appended some of these measurements so you can draw your own
> conclusions.  
> 
> PVC pipe was used for coil forms.  The 4-1/4 inch diameter baluns were wound
> 
> on thin-walled PVC labeled "4 inch sewer pipe".  This material makes an
> excellent balun form.  It's very light weight and easy to work with, and I
> obtained a 10 foot length at the local Home Depot for about 3 dollars.  The
> 6-5/8 inch diameter forms are 6 inch schedule 40 PVC pipe which is much
> thicker, heavier, and more expensive.
> 
> Each test choke was close-wound on a form as a single-layer solenoid using
> RG-213 and taped to hold the turns in place.  The lengths of cable were cut
> so there was about 2 inches excess at each end.  This allowed just enough
> wire at the ends for connections to the HP4193A's probe tip.  After data was
> 
> collected for each single-layer configuration, the PVC form was removed, the
> 
> turns were bunched together and taped formless, and another set of
> measurements 
> was taken.  I have only included the "bunched" measurements in the table for
> 
> one of the baluns, but the trend was the same in each case.  When compared
> to 
> the single-layer version of the same diameter and number of turns, the
> bunched 
> baluns show a large downward shift in parallel self-resonance frequency and
> poor choking reactance at the higher frequencies.
> 
> 
> 
> Interpreting the Measurements
> -----------------------------
> All the baluns start out looking inductive at low frequencies, as indicated
> by 
> the positive phase angles.  As the frequency is increased, a point is
> reached 
> where the capacitance between the windings forms a parallel resonance with
> the 
> coil's inductance.  Above this frequency, the winding reactance is reduced
> by 
> this capacitance. The interwinding capacitance increases with the number of
> turns and the diameter of the turns, so "more is not always better".
> 
> The effects of a large increase in interwinding capacitance is evident in
> the
> measurements on the balun with the bunched turns.  This is probably a result
> of the first and last turns of the coil being much closer together than the
> single-layer coil.
> 
> An important requirement of these baluns is that the magnitude of the
> winding
> reactance be much greater than the load impedance.  In the case of a 50 ohm
> balanced antenna, the balun's winding impedance is effectively shunted
> across
> one half the 50 ohm load impedance, or 25 ohms.  A reasonable critera for
> the
> balun's winding impedance for negligible common mode current in the shield
> is
> that it be at least 20 times this, or 500 ohms.  The measurements show, for
> example, that 6 turns 4-1/4 inches in diameter meet this criteria from 14 to
> 35 MHz.  
> 
> The measurement data also reveals the power loss these baluns will exhibit.
> Each of the measurement points can be transformed from the polar format of
> the
> table to a parallel equivalent real and reactive shunt impedance.  The power
> dissipated in the balun is then the square of the voltage across it divided
> by
> the real parallel equivalent shunt impedance.  While this calculation can be
> made for each measurement point, an approximate number can be taken directly
> from the tables at the parallel resonance points.  At 0 degrees phase angle
> the magnitude numbers are pure resistive.  I didn't record the exact
> resonance
> points, but it can be seen from the tables that the four single-layer baluns
> are all above 15K ohms, while the ferrite bead balun read about 1.4K.  These
> baluns see half the load voltage, so at 1500 watts to a 50 ohm load, the
> power
> dissipated in the coaxial baluns will be less than 1.3 watts, and the
> ferrite
> bead balun will dissipate about 13.4 watts (neglecting possible core
> saturation and other non-linear effects).  These losses are certainly
> negligible.  At 200 ohms load impedance, the losses are under 5 watts for
> the
> coaxial baluns and 53.6 watts for the ferrite beads.
> 
> 
> 
> Conclusions
> -----------
> - A 1:1 coaxial balun with excellent choking reactance for 10 through 20
> meters can be made by winding 6 turns of RG-213 on inexpensive 4 inch PVC
> sewer pipe.  
> 
> - For 40 or 30 meters, use 12 turns of RG-213 on 4 inch PVC sewer pipe.
> 
> - Don't bunch the turns together.  Wind them as a single layer on a form.
> Bunching the turns kills the choking effect at higher
> frequencies.
> 
> - Don't use too many turns.  For example, the HyGain manuals for my 10 and
> 15
> meter yagis both recommend 12 turns 6 inches in diameter.  At the very least
> this is about 3 times as much coax as is needed, and these dimensions
> actually
> give less than the desired choking impedance on 10 and 15 meters.
> 
> 
> 
> Measurements
> ------------
> Magnitude in ohms, phase angle in degrees, as a function of frequency in Hz,
> for various baluns.
> 
> 6 Turns    12 Turns     4 Turns     8 Turns     8 Turns
> Ferrite
> 4-1/4 in    4-1/4 in    6-5/8 in    6-5/8 in    6-5/8 in
> beads
> sngl layer  sngl layer  sngl layer  sngl layer    bunched
> (Aztec)
> ----------  ----------  ----------  ----------  ----------
> ----------
> Frequency  Mag Phase   Mag Phase   Mag Phase   Mag Phase   Mag Phase   Mag
> Phase 
> 1.00E+06    26  88.1    65  89.2    26  88.3    74  89.2    94  89.3   416
> 78.1 
> 2.00E+06    51  88.7   131  89.3    52  88.8   150  89.3   202  89.2   795
> 56.1 
> 3.00E+06    77  88.9   200  89.4    79  89.1   232  89.3   355  88.9  1046
> 39.8 
> 4.00E+06   103  89.1   273  89.5   106  89.3   324  89.4   620  88.3  1217
> 26.6 
> 5.00E+06   131  89.1   356  89.4   136  89.2   436  89.3  1300  86.2  1334
> 14.7 
> 6.00E+06   160  89.3   451  89.5   167  89.3   576  89.1  8530  59.9  1387
> 3.6 
> 7.00E+06   190  89.4   561  89.5   201  89.4   759  89.1  2120 -81.9  1404
> -5.9 
> 8.00E+06   222  89.4   696  89.6   239  89.4  1033  88.8  1019 -85.7  1369
> -15.4 
> 9.00E+06   258  89.4   869  89.5   283  89.4  1514  87.3   681 -86.5  1295
> -23.7 
> 1.00E+07   298  89.3  1103  89.3   333  89.2  2300  83.1   518 -86.9  1210
> -29.8 
> 1.10E+07   340  89.3  1440  89.1   393  89.2  4700  73.1   418 -87.1  1123
> -35.2 
> 1.20E+07   390  89.3  1983  88.7   467  88.9 15840  -5.2   350 -87.2  1043
> -39.9 
> 1.30E+07   447  89.2  3010  87.7   556  88.3  4470 -62.6   300 -86.9   954
> -42.7 
> 1.40E+07   514  89.3  5850  85.6   675  88.3  2830 -71.6   262 -86.9   901
> -45.2 
> 1.50E+07   594  88.9 42000  44.0   834  87.5  1910 -79.9   231 -87.0   847
> -48.1 
> 1.60E+07   694  88.8  7210 -81.5  1098  86.9  1375 -84.1   203 -87.2   778
> -51.8 
> 1.70E+07   830  88.1  3250 -82.0  1651  81.8   991 -82.4   180 -86.9   684
> -54.4 
> 1.80E+07   955  86.0  2720 -76.1  1796  70.3   986 -67.2   164 -84.9   623
> -45.9 
> 1.90E+07  1203  85.4  1860 -80.1  3260  44.6   742 -71.0   145 -85.1   568
> -51.2 
> 2.00E+07  1419  85.2  1738 -83.8  3710  59.0  1123 -67.7   138 -84.5   654
> -34.0
> 2.10E+07  1955  85.7  1368 -87.2 12940 -31.3   859 -84.3   122 -86.1   696
> -49.9 
> 2.20E+07  3010  83.9  1133 -87.8  3620 -77.5   708 -86.1   107 -85.9   631
> -54.8 
> 2.30E+07  6380  76.8   955 -88.0  2050 -83.0   613 -86.9    94 -85.5   584
> -57.4 
> 2.40E+07 15980 -29.6   807 -86.3  1440 -84.6   535 -86.3    82 -85.0   536
> -58.8 
> 2.50E+07  5230 -56.7   754 -82.2  1099 -84.1   466 -84.1    70 -84.3   485
> -59.2 
> 2.60E+07  3210 -78.9   682 -86.4   967 -83.4   467 -81.6    60 -82.7   481
> -56.2 
> 2.70E+07  2000 -84.4   578 -87.3   809 -86.5   419 -85.5    49 -81.7   463
> -60.5 
> 2.80E+07  1426 -85.6   483 -86.5   685 -87.1   364 -86.2    38 -79.6   425
> -62.5 
> 2.90E+07  1074 -85.1   383 -84.1   590 -87.3   308 -85.6    28 -75.2   387
> -63.8 
> 3.00E+07   840 -83.2   287 -75.0   508 -87.0   244 -82.1    18 -66.3   346
> -64.4 
> 3.10E+07   661 -81.7   188 -52.3   442 -85.7   174 -69.9     9 -34.3   305
> -64.3 
> 3.20E+07   484 -78.2   258  20.4   385 -83.6   155 -18.0    11  37.2   263
> -63.2 
> 3.30E+07   335 -41.4  1162 -13.5   326 -78.2   569  -0.3    21  63.6   212
> -58.0 
> 3.40E+07   607 -32.2   839 -45.9   316 -63.4   716 -57.6    32  71.4   183
> -40.5 
> 3.50E+07   705 -58.2   564 -56.3   379 -69.5   513 -72.5    46  76.0   235
> -29.6
> 
> 
> ------------------------------
> 
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> 
> End of TowerTalk Digest, Vol 8, Issue 77
> ****************************************
>