I'm not sure who was questioning the integrity of LMR400, but here's my take on
the stuff. About a year ago, I replaced most of my coax with LMR 500 (I think
it
was 500...it was the stuff with comparable specs to 9913. I found it was sooo
flexible I was afraid the center conductor would migrate and short if it kinked,
and it did kink in normal handling. Fortunately, I haven't had any problems,
but I
just had a gut feeling that the stuff wasn't tough and I would never use it
again! JACK W1WEF
Tower Talk Digest wrote:
> Tower Talk Digest Monday, April 5 1999 Volume 02 : Number 127
>
> In this issue:
>
> Re: [TowerTalk] C4 Repaired -Coax Damage ?
> [TowerTalk] Re: [Antennas] TH3
> [TowerTalk] Rohn 45G Weight
> [TowerTalk] Verticals etc
> RE: [TowerTalk] Rohn 45G Weight
> Re: [TowerTalk] Rohn 45G Weight
> Re:[TowerTalk] Gin Pole Strength
> [TowerTalk] modeling log periodic arrays
> [TowerTalk] Hy-Gain BN-4000
> [TowerTalk] 4-point guying- per catalog
> [TowerTalk] Re: C4 Repaired -Coax Damage ?
> [TowerTalk] Rohn 25 vs 45 ?
> [TowerTalk] C4 40 Meter Coax Repair
> [TowerTalk] Hybrid Quad Antenna from T.G.M.
> Re: [TowerTalk] C4 40 Meter Coax Repair
> [TowerTalk] Hybrid Quad Antenna from T.G.M.
> [TowerTalk] Re: C4 40 Meter Coax Repair
> [TowerTalk] KT 34XA 15 redux
> [TowerTalk] Force 12 rotating 40 meter Dipoles
> Re: [TowerTalk] KT 34XA 15 redux
>
> See the end of the digest for information about towertalk-digest
>
> ----------------------------------------------------------------------
>
To: <towertalk@contesting.com>
> Date: Sun, 4 Apr 1999 21:05:52 -0700
> From: "Ron Castro" <ronc@sonic.net>
> Subject: Re: [TowerTalk] C4 Repaired -Coax Damage ?
>
> Carefully inspect the PVC element insulators where the elements clamp to the
> boom. I believe they are made of PVC, and with age and UV exposure, could
> have cracked when the lifting cable snapped. It's also possible that one of
> the other elements sustained damage causing intermittent conditions that
> interact with the 40 meter element. All of the elements are insulated from
> the boom on the C-4.
>
> In a previous post, you mentioned you were considering welding the sections
> of the tower together rather than install a new cable. Instead of welding,
> have you considered putting large clamps on each of the movable sections,
> lifting each section with a gin pole, then clamping the bottom to keep it
> from telescoping back into the larger section? That will at least give you
> the option of re-cabling at some later date, not to mention making it easier
> to remove the tower when the time comes.
>
> Ron N6AHA
>
> > 40 meter element now "hears" great, but on transmit, much
> > crackling and distortion occurs, almost sounding as if RF
> > arcing is occurring per fellows on the Hawaii Afternoon net
> > yesterday. Don't know the innards of LMR-400, but is it
> > possible it was permanently damaged in some way --
> > stretch of the inner conductor, crack in it, or now the outer
> > conductor is permanently pinched in toward the inner, and
> > arcs. This "arcing" occurs even with only 50 watts output!
> >
> > I hope the problem can be solved by replacing the coax,
> > and that some problem to the 40 meter dipole, unnoticed
> > yesterday when all was at ground level, has not occurred.
> > Visually the dipole, linear loading, matching coil, etc.,all
> > appeared just fine.
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 08:30:38 EDT
> From: JSheinb785@aol.com
> Subject: [TowerTalk] Re: [Antennas] TH3
>
> I've never had ANY luck with baluns & have used chokes with great sucess.
> 73, Joe WD5FHG, Corpus Christi TX
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 09:47:48 -0400
> From: Setzler James M NPRI <SetzlerJM@Code80.NPT.NUWC.NAVY.MIL>
> Subject: [TowerTalk] Rohn 45G Weight
>
> What is the approx. weight of a 10' section of 45G? The Rohn webpage is no
> help and catalog is at home.
>
> thanks &
> 73 James / k1sd
> Rhode Island
>
> >> setzlerjm@code80.npt.nuwc.navy.mil <<
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 13:25:55 +0100
> From: "Clive Penna" <clive@gm3poi.prestel.co.uk>
> Subject: [TowerTalk] Verticals etc
>
> Thanks to all that replied re pegging down radials, I now have a few ideas.
> Can any body remind me of the formula for calculating the equivalent
> diameter of a triangular tower in order to do some
> resonance checks with software. 73 Clive GM3POI
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 10:21:56 -0400
> From: Setzler James M NPRI <SetzlerJM@Code80.NPT.NUWC.NAVY.MIL>
> Subject: RE: [TowerTalk] Rohn 45G Weight
>
> Rohn 45G straight section: 70 pounds.
>
> thanks KZ1X, K5TR, W4BSG, W0UCE, N4TZ
>
> 73 James / k1sd
> Rhode Island
>
> >> setzlerjm@code80.npt.nuwc.navy.mil <<
>
> > ----------
> > From: Setzler James M NPRI
> > Sent: Monday, April 5, 1999 9:47 AM
> > To: 'Towertalk'
> > Subject: [TowerTalk] Rohn 45G Weight
> >
> >
> > What is the approx. weight of a 10' section of 45G? The Rohn webpage is
> > no
> > help and catalog is at home.
> >
> > thanks &
> > 73 James / k1sd
> > Rhode Island
> >
> > >> setzlerjm@code80.npt.nuwc.navy.mil <<
> >
> >
> > --
> > FAQ on WWW: http://www.contesting.com/towertalkfaq.html
> > Submissions: towertalk@contesting.com
> > Administrative requests: towertalk-REQUEST@contesting.com
> > Problems: owner-towertalk@contesting.com
> > Search: http://www.contesting.com/km9p/search.htm
> >
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 10:46:12 EDT
> From: K7LXC@aol.com
> Subject: Re: [TowerTalk] Rohn 45G Weight
>
> In a message dated 99-04-05 09:56:34 EDT, SetzlerJM@Code80.NPT.NUWC.NAVY.MIL
> writes:
>
> > What is the approx. weight of a 10' section of 45G? The Rohn webpage is no
> > help and catalog is at home.
>
> Seventy pounds.
>
> Cheers, Steve K7LXC
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 05 Apr 1999 07:43:30 PDT
> From: "Mark, N1LO" <n1lo@hotmail.com>
> Subject: Re:[TowerTalk] Gin Pole Strength
>
> Greetings from Gloucester,
> I missed this thread over the weekend. It sure has made for interesting
> reading with lots of good, thought-provoking, amicable discussion.
>
> I may have missed it, but no one mentioned that you should always use a
> turning block at the base of the tower for your haul rope to keep the
> haul load as close to the axis of the gin pole as possible. Some
> scenarios of pulleys described might lead people to envision the haul
> rope going straight from the hauler up at an angle to the pulley on the
> gin pole. Don't do this! As already pointed out, you want to keep side
> loads to a minimum.
>
> Be sure that your turning block (pulley) uses a safety hook or locking
> carabiner to attach it securely to a tower rung. DO NOT rely on the
> tension of the haul rope to keep a simple hook engaged!
>
> I witnessed a scary accident where the turning block unhooked itself,
> releasing a section of Rohn 45 to free fall for about 30 feet. It
> tumbled a little and got off to the side of the gin pole. When the slack
> in the haul rope pulled tight again, the resulting shock load on the
> Rohn gin pole bent it permanently. Fortunately, the tower workers and
> crew were only shaken and not hurt (They got "sewing-machine legs").
> Don't underestimate the energy that develops in a free fall. Shock loads
> are easily several times a normal load. This is why the 'working load'
> of a device is much lower than its ultimate breaking strength.
>
> I think some of the confusion in the load issue came from where the
> tackle blocks were placed. One block must be on the gin pole and the
> other must be on the load in order to reduce the vertical load on the
> pole.
>
> If the blocks are only on the haul line, as some of you undoubtably
> envisioned, and there is no change
> to the rig between the gin pole and the load, then the vertical load on
> the pole will not change and will be about twice the load weight.
>
> Alas there is no free lunch. Aren't we always running into compromises?
> The *work* that is done (force times distance) *is* still the same no
> matter how you rig your tackle blocks. Friction in the sheaves actually
> increases our work a little. If you have a 2:1 mechanical advantage, you
> have to pull the haul line twice as far. If 3:1, then you have to slog
> through three times as much rope. And, of course, you have to have a
> looooooong rope. And tall glass of iced tea afterwards.
>
> - --...MARK_N1LO...--
>
> Get Your Private, Free Email at http://www.hotmail.com
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 11:39:06 EDT
> From: CP2235@aol.com
> Subject: [TowerTalk] modeling log periodic arrays
>
> Hello,
>
> tried to model some log periodics few days ago. The modeling program I am
> using is K6STI's NECwires version 2.02 which uses the NEC2 modeling algorithm.
> I used the "transmission lines" feature instead of entering the transmission
> lines as separate wires. The results I got were not very encouraging.
> What is the shared knowledge on how exact this modeling program acts on log
> periodic antennas? Are there any known problems (like the corners on quad
> modeling, which need special attention)?. How do other modeling programs play
> on this subject? Any comments are highly appreciated.
> And what was the adress of the antenna modeling reflector?
>
> 73 and happy easter
> Con DF4SA
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 05 Apr 1999 11:37:05 -0400
> From: Bob Thacker <k3gt@pgh.net>
> Subject: [TowerTalk] Hy-Gain BN-4000
>
> Getting close to putting up a second hand TH-11DX. Put a lot of work in
> refurbishing it and now looking at the balun. How does one test this
> beast and what do y'all feel about using a choke instead of the BN-4000?
> A new BN-4000 is about 80 bucks, so rather use it if its ok...any
> thoughts?
> 73,
> Bob, K3GT
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 05 Apr 1999 11:03:44 -0500
> From: Bill Aycock <baycock@hiwaay.net>
> Subject: [TowerTalk] 4-point guying- per catalog
>
> I just had reason to make a reference to the Rohn catalog- the direct
> attachment of guys IS still in the catalog, in the section on Fold-Over
> towers. In the Drawing, it shows one guy to each of two legs, and one leg
> with two guys. The guys are looped so that they are inside the "point" of
> the welded-in braces, and not just looped around the leg.
>
> I think Rohn probably intended to specify only Brackets for guys, but
> forgot the drawing that goes with the Fold-Overs
>
> Bill- W4BSG
> - -
> Bill Aycock --- Persimmon Hill
> Woodville, Alabama, US 35776
> (in the N.E. corner of the State)
> W4BSG -- Grid EM64vr
> baycock@HiWAAY.net
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 08:46:32 -0400
> From: n8ug@juno.com
> Subject: [TowerTalk] Re: C4 Repaired -Coax Damage ?
>
> Hi Jim
> Have been following the sad tale with interest and sympathy - glad to
> hear that the antenna is repaired.
> There is little doubt to me that the coax is destroyed. LMR400 will not
> take a kink under load and re-straightening. The AL center conductor is
> tough and no doubt cavitated the dielectric, which would not re-form upon
> straightening. Further, the bending and tension is likely to have opened
> the copper surface of the conductor which would create serious
> aberrations in the RF carrying capability of the surface. Fracture of the
> whole conductor would cause arcing, as well, where a tiny shard of copper
> could still maintain rx continuity.
> Let us know if we can help in any way. BTW, the 259B is supposed to have
> TDR capability - haven't tried it for that purpose, but it might be
> interesting. We've used our TDR to present scope pics of damage points on
> coax.
> 73,
> Press
>
> On Sun, 4 Apr 1999 14:19:10 -1000 "Jim Reid" <jreid@aloha.net> writes:
> >Aloha,
> >
> >Well, the Saturday morning repair to the broken boom of the
> >C4 only took 6 hours!! Most of the time was spent taking
> >down the remnants of the antenna, then literally driving into
> >each boom half the splice tube -- very heavy Al tubing which
> >must have been 1 or 2 mils larger in OD than the 2" boom
> >tubing ID of the C4! Anyway, C4 is all repaired and back up
> >on the MA-550, which is, of course, still collapsed down to
> >20 some feet high. Unfortunately, found at the top, that it
> >appears the upper section of the tower fell with enough force
> >to bend its way further down than the stop which was supposed
> >to stop it, hi. That repair is for some other day.
> >
> >Now, the back part of the broken C4 boom was dangling some
> >8 feet above the ground, hanging suspended by the LMR-400
> >coax running up to the 40 meter Force 12 dipole. Noticed it was
> >"kinked" or sharply bent at the bend from where it was dangling
> >from one of the US Tower coax support rings up on the tower.
> >And, it must have had quite a bit of stretching force when it
> >stopped the antenna back part from the fall.
> >
> >Thought nothing of it really, used a bit of finger action to reshape
> >the coax back to round, and put the antenna back up after the
> >boom splice was installed.
> >
> >40 meter element now "hears" great, but on transmit, much
> >crackling and distortion occurs, almost sounding as if RF
> >arcing is occurring per fellows on the Hawaii Afternoon net
> >yesterday. Don't know the innards of LMR-400, but is it
> >possible it was permanently damaged in some way --
> >stretch of the inner conductor, crack in it, or now the outer
> >conductor is permanently pinched in toward the inner, and
> >arcs. This "arcing" occurs even with only 50 watts output!
> >
> >I hope the problem can be solved by replacing the coax,
> >and that some problem to the 40 meter dipole, unnoticed
> >yesterday when all was at ground level, has not occurred.
> >Visually the dipole, linear loading, matching coil, etc.,all
> >appeared just fine.
> >
> >Can it be a damaged coax that would cause these symptoms?
> >Arc was too fast to see any impact on my vswr indicator, but
> >guys on the net reported their S-matter reading seemed to
> >actually increase during or immediately after the crackle
> >sound, or arc, or whatever it is.
> >
> >73, Jim, KH7M
> >On the Garden Island of Kauai
> >
> >
> >
>
> Press Jones, N8UG, The Wireman, Inc., Landrum, SC, 29356
> Sales (800)727-WIRE(9473) or orders@thewireman.com
> Tech help (864)895-4195 or n8ug@thewireman.com
> http://www.thewireman.com and the WIRELINE bargain page
> Our 22nd year!
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 11:51:23 -0400
> From: "Dennis Shoaf" <dshoaf@Mondobaking.com>
> Subject: [TowerTalk] Rohn 25 vs 45 ?
>
> I am in the planning process of putting up a 130' tower in NE Alabama. I
> will put up a M2 3 ele 40 mtr yagi atop. I want to put up Rohn 45, but my
> budget may not allow it (only 3k in budget). Can I safely put that type of
> Ant. @ 130' with Rohn 25, if I follow all of Rohn guying specs and not do
> any potential damage to the tower or worse. Any and all advice/suggestion
> are highly appreciated.
>
> One strange question. Does Rohn make a 45/25 Reducer ? Where as if I
> wanted to go up 70 ft with Rohn 45, then rest of the way with 25 ? May
> seem strange or may not serve any other purpose other than saving
> money......Agn, any opinions are appreciated......
>
> Dennis, W4DWS
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 09:23:10 -1000
> From: "Jim Reid" <jreid@aloha.net>
> Subject: [TowerTalk] C4 40 Meter Coax Repair
>
> Aloha,
>
> Got super info from Press Jones, The Wireman about the LMR-400:
>
> "Have been following the sad tale with interest and sympathy - glad to
> hear that the antenna is repaired.
> There is little doubt to me that the coax is destroyed. LMR400 will not
> take a kink under load and re-straightening. The AL center conductor is
> tough and no doubt cavitated the dielectric, which would not re-form upon
> straightening. Further, the bending and tension is likely to have opened
> the copper surface of the conductor which would create serious
> aberrations in the RF carrying capability of the surface. Fracture of the
> whole conductor would cause arcing, as well, where a tiny shard of copper
> could still maintain rcv continuity."
>
> My great helpers, Jim, WH6FG (who loves to be up on towers with
> his trusty safety belt) and John, WH6EY, (Jim's ground support guy)
> were back at 4 o'clock Easter Sunday afternoon to make a quick
> coax replacement. I took another length of LMR-400 from one of
> my verticals. Will have to have Press send me some PL UHF
> males to cut and repair the remains of the LMR-400 to get my
> back-up vertical going on the high bands again, hi.
>
> Jim went up the pole, unscrewed the damaged coax, and had a lot
> of water pour out of the connector on him!, even though well taped with
> Scorch #23. However, as it had rained heavily for several days
> after the "fall", and the coax was hanging straight down, we
> decided that may be how the water got in. Anyway, Jim decided
> we should warm the Force 12 B-1 balun SO-239 connectored balun end
> to attempt pulling any more water out of that area and to thoroughly
> dry the connector. When all appeared dry, Jim screwed on the replacement
> length of LMR, taped, and then used The Wireman's coax seal, very
> sticky stuff, then more tape.
>
> Now for the RF test. Sure enough, the arcing, or whatever problem seems
> "almost" gone! Well, why not all gone? No trace of a problem now at
> 50 watts, but, just noticeable, "ffffffp.......fffffffp" sounds at the
> onset and close of
> words on SSB at 100 watts out, but no detectable distortion of any
> sort on a 100 watt 40M CW signal ---curiousor and curiousor.
>
> We had guys monitoring the signals both right out front of my QTH on
> a truck mounted mobile rig, and also a couple down on the Big Island
> of Hawaii -- all gave exactly the same report as above.
>
> Will A/B the antenna with my long wire which will tune up on 40 this
> afternoon to be sure what we are hearing is not a rig/shack set-up
> ground problem or RF pick up directly from the antenna. BTW, with
> the MA-550 down, the radiator element is just about exactly 50 feet
> on the diagonal from the rig set up in the shack. One fellow speculated
> the RF field from proximity pick up of just 50 feet could be a source
> or trouble-- is that possible with what I believe I have as a good RF
> ground here? It is a long way back via 450 ohm ladder line to where
> the long wire (600 feet) antenna is placed, so essentially no chance of
> an intense, near RF field being a problem from that one, I should think.
>
> We decided to button up the project for now, and see if after a little
> use if some residual water, in the balun(?), might be the problem,
> and might go away. Otherwise, guess should consider replacing
> the Force 12 B-1 balun. Do not know if it is possible for water,
> from inside the SO-239 socket to get inside the B-1 balun,
> or into the coax inside. If possible, that might be a problem which
> only replacing the balun, rather than a period of use, could fix.
>
> Status for now.
>
> 73, Jim, KH7M
> On the Garden Island of Kauai
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 16:13:07 EDT
> From: Abrayten@aol.com
> Subject: [TowerTalk] Hybrid Quad Antenna from T.G.M.
>
> I have seen the Hybrid Quad from T.G.M. in QST, yet would like to know about
> its performance from those who have used it. I realize that its a compromise,
> compared to some of the larger antennas that have been reviewed in the
> archives, yet I still would like to get some pros and cons, if possible. THX.
>
>
> Drew Braytenbah
>
>
> KD4QCX
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 05 Apr 1999 21:28:31 GMT
> From: k2av@qsl.net (Guy Olinger, K2AV)
> Subject: Re: [TowerTalk] C4 40 Meter Coax Repair
>
> When the half antenna was hanging by the coax, exactly what on the
> antenna end was transferring the support to the antenna? Lots of black
> tape, or possibly the coax PL259/SO239 at the B1 balun? If so, the
> connection, either ground or center conductor or both, may have
> loosened inside the PVC cover. Seriously doubt Tom designed B1 to
> suspend much weight from the SO239 or take a sudden jerk. Drop a
> bowling ball on your toe from eye level to approximate the forces
> involved. (It's only 16 pounds...)
>
> Pretty sure that the B1 is flooded and sealed at manufacture, so if
> water came out of it, a good chance that the seal integrity was
> compromised by stretching/bending and internal contact at risk.
>
> Best 'o luck chasing this one down...
>
> Guy.
>
> On Mon, 5 Apr 1999 09:23:10 -1000, you wrote:
>
> > .....
> >Jim went up the pole, unscrewed the damaged coax, and had a lot
> >of water pour out of the connector on him!, even though well taped with
> >Scorch #23. However, as it had rained heavily for several days
> >after the "fall", and the coax was hanging straight down, we
> >decided that may be how the water got in. Anyway, Jim decided
> >we should warm the Force 12 B-1 balun SO-239 connectored balun end
> >to attempt pulling any more water out of that area and to thoroughly
> >dry the connector. When all appeared dry, Jim screwed on the replacement
> >length of LMR, taped, and then used The Wireman's coax seal, very
> >sticky stuff, then more tape.
> >
> >Now for the RF test. Sure enough, the arcing, or whatever problem seems
> >"almost" gone! Well, why not all gone? No trace of a problem now at
> >50 watts, but, just noticeable, "ffffffp.......fffffffp" sounds at the
> >onset and close of
> >words on SSB at 100 watts out, but no detectable distortion of any
> >sort on a 100 watt 40M CW signal ---curiousor and curiousor.
> >
>
> > .....
> 73, Guy
> - --. .-..
>
> Guy Olinger, K2AV
> k2av@qsl.net
> Apex, NC, USA
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 09:44:59 EDT
> From: Abrayten@aol.com
> Subject: [TowerTalk] Hybrid Quad Antenna from T.G.M.
>
> I have seen the Hybrid Quad from T.G.M. in QST, yet would like to know about
> its performance from those who have used it. I realize that its a compromise,
> compared to some of the larger antennas that have been reviewed in the
> archives, yet I still would like to get some pros and cons, if possible. THX.
>
>
> Drew Braytenbah
>
> KD4QCX
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 05 Apr 99 15:24:13 PDT
> From: "Force 12, Inc." <force12@tcsn.net>
> Subject: [TowerTalk] Re: C4 40 Meter Coax Repair
>
> Good afternoon.
>
> Glad you are making progress after the tower fall.
>
> Thought it might be beneficial to know how a B-1 balun is made, so it
> will be easy to understand why water cannot get inside:
> The internal coax is RG-303 teflon, which is attached to an in-line female UHF
> connector (not a modified bulkhead SO-239). The coax is crimped and then
> soldered. We then inject silicon sealant behind the center pin for a moisture
> barrier. The 50+ beads are placed over the coax and the coax transitions to
> PVC
> jacketed wire pigtails. The outer PVC tube is slipped over this assembly, with
> an "O" ring at the UHF connector end. The epoxy filler material is inserted
> and
> the assembly is placed inside a vacuum chamber, which removes all voids (a
> common problem on baluns). After the filler is set, the cap is back-filled
> with
> sealant and set in place. The balun is then tested. Should have mentioned that
> the UHF connector is "splined" to seat securely inside the PVC outer tube.
>
> When using these baluns on DXpeditions to Jamaica (6Y2A), we clean them by
> tossing them in the swimming pool, along with other tubing and parts (with
> the OK of the grounds/pool keeper).
>
> About the worst someone can do to one of these baluns is use pliers on the
> male
> UHF connector, overtighten it and twist the connector inside the balun. Not
> sure
> if anyone has ever done this.
>
> Hope you get the installation back on the air. Your diligence is obvious,
> so it is
> only a matter of time.
>
> 73, Tom, N6BT
> Force 12, Inc.
>
> - ----------
> > Aloha,
> >
> > Got super info from Press Jones, The Wireman about the LMR-400:
> >
> > "Have been following the sad tale with interest and sympathy - glad to
> > hear that the antenna is repaired.
>
> > There is little doubt to me that the coax is destroyed. LMR400 will not
> > take a kink under load and re-straightening. The AL center conductor is
> > tough and no doubt cavitated the dielectric, which would not re-form upon
> > straightening. Further, the bending and tension is likely to have opened
> > the copper surface of the conductor which would create serious
> > aberrations in the RF carrying capability of the surface. Fracture of the
> > whole conductor would cause arcing, as well, where a tiny shard of copper
> > could still maintain rcv continuity."
> >
> > My great helpers, Jim, WH6FG (who loves to be up on towers with
> > his trusty safety belt) and John, WH6EY, (Jim's ground support guy)
> > were back at 4 o'clock Easter Sunday afternoon to make a quick
> > coax replacement. I took another length of LMR-400 from one of
> > my verticals. Will have to have Press send me some PL UHF
> > males to cut and repair the remains of the LMR-400 to get my
> > back-up vertical going on the high bands again, hi.
> >
> > Jim went up the pole, unscrewed the damaged coax, and had a lot
> > of water pour out of the connector on him!, even though well taped with
> > Scorch #23. However, as it had rained heavily for several days
> > after the "fall", and the coax was hanging straight down, we
> > decided that may be how the water got in. Anyway, Jim decided
> > we should warm the Force 12 B-1 balun SO-239 connectored balun end
> > to attempt pulling any more water out of that area and to thoroughly
> > dry the connector. When all appeared dry, Jim screwed on the replacement
> > length of LMR, taped, and then used The Wireman's coax seal, very
> > sticky stuff, then more tape.
> >
> > Now for the RF test. Sure enough, the arcing, or whatever problem seems
> > "almost" gone! Well, why not all gone? No trace of a problem now at
> > 50 watts, but, just noticeable, "ffffffp.......fffffffp" sounds at the
> > onset and close of
> > words on SSB at 100 watts out, but no detectable distortion of any
> > sort on a 100 watt 40M CW signal ---curiousor and curiousor.
> >
> > We had guys monitoring the signals both right out front of my QTH on
> > a truck mounted mobile rig, and also a couple down on the Big Island
> > of Hawaii -- all gave exactly the same report as above.
> >
> > Will A/B the antenna with my long wire which will tune up on 40 this
> > afternoon to be sure what we are hearing is not a rig/shack set-up
> > ground problem or RF pick up directly from the antenna. BTW, with
> > the MA-550 down, the radiator element is just about exactly 50 feet
> > on the diagonal from the rig set up in the shack. One fellow speculated
> > the RF field from proximity pick up of just 50 feet could be a source
> > or trouble-- is that possible with what I believe I have as a good RF
> > ground here? It is a long way back via 450 ohm ladder line to where
> > the long wire (600 feet) antenna is placed, so essentially no chance of
> > an intense, near RF field being a problem from that one, I should think.
> >
> > We decided to button up the project for now, and see if after a little
> > use if some residual water, in the balun(?), might be the problem,
> > and might go away. Otherwise, guess should consider replacing
>
> > the Force 12 B-1 balun. Do not know if it is possible for water,
> > from inside the SO-239 socket to get inside the B-1 balun,
>
> > or into the coax inside. If possible, that might be a problem which
> > only replacing the balun, rather than a period of use, could fix.
> >
> > Status for now.
> >
> > 73, Jim, KH7M
> > On the Garden Island of Kauai
> >
> >
> >
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 21:09:26 -0400
> From: thompson@mindspring.com
> Subject: [TowerTalk] KT 34XA 15 redux
>
> Well I have gotten to the end of the KT34XA saga. All re-capped and new
> balun in place. All measurements set to the 6/19/85 dimensions (Bruce said
> these where the latest. 10 and 20 are below 1.4 over the band and match the
> factory curve. The problem is 15 meters where the SWR is 2.4 to 3 to 1
> across the band. It is almost resistive at the top and bottom of the band
> but 2.4 to 1 not 50 ohms. The only thing I did not have before I got the
> new revisions from Bruce is the B dimension on page 9 which sets 15 meters.
> I will measure the length to the strap on the dual driven elements and the
> reflector first as I can reach those elements from the roof with the tower
> cranked down. The capacitors all check less than 1/2 ohm and the 20 meter
> freq is not affected by the other side of the B strap. KLM says 20 meters
> is based upon length A (to the tip) and only the length changes 20 freq. I
> lengthened the rear reflector as they stated and got 20 meter to a low SWR.
>
> Anyone have any other ideas? I read thru the archives and except for dimem
> B I did everything right. The balun and match are good (I even put the old
> balun back in..same result).
>
> The caps on the front driven element where boiled and cracked and the
> reflector 10 meter section had slid 3". I replaced 3 of the fiberglas
> spacers in all. Damaged by pollution!
>
> Dave K4JRB
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 15:51:46 -1000
> From: "Jim Reid" <jreid@aloha.net>
> Subject: [TowerTalk] Force 12 rotating 40 meter Dipoles
>
> Hi again,
>
> Someone, whose mail I must have deleted, asked the other day how well
> my F-12 EF140S dipole worked, added onto the boom of the C3.
>
> Well, it is the best 40 meter antenna I have ever had! That is why
> I am working so hard to get it to work well again, hi. Mine is the
> shortened version, 37 feet end to end of the elements, with linear
> loading wires which are used to tune for the desired center
> resonant frequency, plus a small coil at the feedpoint to set
> the resulting unit as close to 1:1 vswr as possible. I am certain
> it is better than any other 40 wire dipole, inverted v, or my present
> 40 meter vertical. Of course, it would be nice to have a reflector
> element (and even add a director to that), but in my situation that
> is not going to be possible. I believe the rotating 40 dipole is
> just fine for me. BTW, with a tuner, it works fine on 30 meters
> also.
>
> 73, Jim, KH7M
> On the Garden Island of Kauai
>
> ------------------------------
>
To: <towertalk@contesting.com>
> Date: Mon, 5 Apr 1999 22:02:36 EDT
> From: K7LXC@aol.com
> Subject: Re: [TowerTalk] KT 34XA 15 redux
>
> In a message dated 99-04-05 21:09:39 EDT, thompson@mindspring.com writes:
>
> > Anyone have any other ideas? I read thru the archives and except for dimem
> > B I did everything right. The balun and match are good (I even put the old
> > balun back in..same result).
>
> Try adding to or subtracting from the feedline. It worked for me.
>
> Cheers, Steve K7LXC
>
> ------------------------------
>
> End of Tower Talk Digest V2 #127
> ********************************
>
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