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On Oct 27, 2011 1:36 PM, <towertalk-request@contesting.com> wrote:
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> Today's Topics:
>
> 1. Re: Winding A New Linear Loading Coil for a Cushcraft 402-CD
> (Jim Lux)
> 2. Re: Winding A New Linear Loading Coil for a Cushcraft 402-CD
> (Bill Jackson)
> 3. Re: Solid center conductor LMR400 for crankup tower? (Alan NV8A)
> 4. Equivalent wind load to square ft (Cqtestk4xs@aol.com)
> 5. Re: Equivalent wind load to square ft (Jim Lux)
> 6. Re: Equivalent wind load to square ft (Steve London)
> 7. Hardline on a crankup? Was:Solid center conductor LMR400 for
> crankup tower? (Alan NV8A)
> 8. guy detach in the middle? (chris casey)
> 9. Re: Tower Base Round or Square? (Pete Smith)
>
>
> ---------- Forwarded message ----------
> From: Jim Lux <jimlux@earthlink.net>
> To: towertalk@contesting.com
> Date: Wed, 26 Oct 2011 22:15:39 -0700
> Subject: Re: [TowerTalk] Winding A New Linear Loading Coil for a Cushcraft
> 402-CD
> On 10/26/11 5:28 PM, Charlie Gallo wrote:
>
>>
>> On 10/26/2011 Bill Jackson wrote:
>>
>> My question is directed to those of you who build your own antennas. Is
>>> there
>>> any technique or home brew aide(s) that will assist in getting this coil
>>> wound
>>> tightly with no spacing between the turns? I seem to recall seeing an
>>> article
>>> many moons ago that talked about using a paint stirring stick with a hole
>>> drilled in the end to hold the wire while you wind it around the core.
>>> #12 AWG
>>> is pretty stiff for a 3/4" form and I want to make it look as good as the
>>> factory original.
>>>
>>
>> A place I worked did a LOT of toroidal core winding. One of the ways of
>> keeping the wire neat was they had a spring loaded clamp, that was lined
>> with what was basically a rough, deep synthetic velvet like pad - soft
>> enough NOT to scratch the wire being pulled through, it - it was firmly
>> attached to the machine, and the wire was drawn through it, effectively
>> keeping tension on the wire, as the form was turned (we also did straight
>> forms, I cores etc, not just torroids (which require a special machine,
>> kinda nifty)
>>
>> One nifty way of guiding the wire once you make the clamp is with a lathe
>> - put the form "between centers", and run the lathe slowly, with the proper
>> feed on the carriage, and it advances the wire for you
>>
>>
> I've wound coils on a lathe (I used to build Tesla coils, and putting 1000
> turns on a coil is pretty tedious by hand.) The challenge is that once you
> engage the clutch on the lathe, you have to keep up and pray that the spool
> doesn't have a dent or the wire tangle. Shades of Lucy and the chocolate
> boxes.
>
>
> The last few times: foot switch and a small motor. A variable speed drill
> also works pretty well. I also did one with a foot pedal (variable resistor
> type) to a variable speed motor drive feeding the the lathe. That was great.
>
> If you need lots of turns....
> Put the spool of wire on the floor on it's side
> bring the wire up to where you're winding
> Put a funnel over the wire, open end down (towards the spool), so that it
> sits on the rim of the spool.
>
> A leather glove or piece of chamois cloth to hold the wire, and off you go.
>
>
> I've never tried this with anything bigger than about AWG16. For AWG 12 or
> 10 or bigger, I've wound it by hand, because it's usually not that many
> turns, and it's faster just to wind by hand than set up the jig or motor.
>
>
>
>
> ---------- Forwarded message ----------
> From: "Bill Jackson" <k9rz@radiks.net>
> To: <towertalk@contesting.com>
> Date: Thu, 27 Oct 2011 06:27:05 -0500
> Subject: Re: [TowerTalk] Winding A New Linear Loading Coil for a Cushcraft
> 402-CD
> Thanks everyone for all of the suggestions.
>
> I was able to wind the coil by hand by placing the element tip in the bench
> vise. I just kept working the wire on the 3/4" fiberglass tube until it
> looked
> nice and tight along the entire length. It should be as good as new once I
> cover it with the glue filled heat shrink tubing.
>
> 73 de Bill, K9RZ
>
>
>
>
>
> ---------- Forwarded message ----------
> From: Alan NV8A <nv8a@charter.net>
> To: TowerTalk@contesting.com
> Date: Thu, 27 Oct 2011 08:48:00 -0400
> Subject: Re: [TowerTalk] Solid center conductor LMR400 for crankup tower?
> On 10/26/11 09:58 pm, krishna kanakasapapathi wrote:
>
> I am installing the DB18 on a 75ft crankup. Have a roll of LMR400, the
>> solid center conductor type.
>> I thought i might just ask before i cut the cable from the roll. Any
>> possible issues with
>> using the LMR400 on a crankup?
>>
>> I have arms mounted on each of the 3 sections to keep the cables away
>> from the telescoping sections.
>>
>
> I use Davis BuryFlex -- two runs of it at present. They are bundled
> together with the rotator cables with electrical tape at intervals and
> suspended from the uppermost standoff using Kellem grips. At the bottom I
> guide the bundle into a large trash bin with a hole in the lid as the tower
> (HDX-555) comes down.
>
> (I really need something with lower loss for the UHF antenna -- LMR600UF?)
>
> 73
>
> Alan NV8A
>
>
>
> ---------- Forwarded message ----------
> From: Cqtestk4xs@aol.com
> To: TOWERTALK@contesting.com
> Date: Thu, 27 Oct 2011 09:56:15 -0400 (EDT)
> Subject: [TowerTalk] Equivalent wind load to square ft
> A friend of mine is thinking of putting up some wind generators and has
> asked for my advice. The only information he can give me for the wind
> load
> is 300# at 100 MPH. I know that makes sense to some, but I'm used to
> square
> ft loads for ham antennas.
>
> Is there some kind of simple equivalency that I can use to figure out what
> this would mean if we were talking plain old square ft antenna load? I
> don't know if I worded this exactly right but I hope someone can help me
> on
> this.
>
> Bill K4XS/KH7XS
>
>
> ---------- Forwarded message ----------
> From: Jim Lux <jimlux@earthlink.net>
> To: towertalk@contesting.com
> Date: Thu, 27 Oct 2011 07:34:35 -0700
> Subject: Re: [TowerTalk] Equivalent wind load to square ft
> On 10/27/11 6:56 AM, Cqtestk4xs@aol.com wrote:
>
>> A friend of mine is thinking of putting up some wind generators and has
>> asked for my advice. The only information he can give me for the wind
>> load
>> is 300# at 100 MPH. I know that makes sense to some, but I'm used to
>> square
>> ft loads for ham antennas.
>>
>
> What they have done is calculate the total load at 100 mi/hr.
>
> A rule of thumb is that wind load in pounds is
> Area(sq ft)* windspeed (mi/hr)^2/391
>
> So, his windload at 50 mi/hr would be 75 lbs.
>
> However, this makes the assumption that the drag coefficient is constant
> (that is, that the drag goes as the square of the airspeed), which is
> probably not true for a wind generator, and certainly isn't true for
> something like a round tube at airspeeds we see.
>
> the real equation is Force = rho*Cd*A*v^2, where
> rho is the density of the fluid (air)
> Cd is the drag coefficient
> A is the area
> v is the fluid speed.
>
> The problem is that Cd varies quite a lot with speed, for low speeds (tens
> of mi/hr) and common dimensions (inches). What most people do is either
> assume Cd=1 (a sort of tending to the worst case) or take the worst case Cd
> (say, 1.3) and increase the "effective area" by that amount, so you can use
> the equation assuming Cd=1
>
>
>
>> Is there some kind of simple equivalency that I can use to figure out
>> what
>> this would mean if we were talking plain old square ft antenna load? I
>> don't know if I worded this exactly right but I hope someone can help me
>> on
>> this.
>>
>
>
> What a tower designer does is take the "design wind speed" and the "maximum
> force" and work backwards to a square footage rating. Here's an example...
> Say the tower is designed for 70 mi/hr winds AND can take a 100 pound load
> at the top. The designer plugs in:
>
> A = 100*391/70^2 = about 8 square feet.
>
> Then they publish that in their spec sheet: "Can hold an 8 square foot
> antenna at 70 mi/hr"
>
> (but of course, the real design limit is some force... whether it's an
> antenna in the wind or a winch cable from your evil neighbor pulling the
> tower over, it doesn't matter to the tower)
>
> So, if you wanted to convert your friend's wind generator into an
> "equivalent antenna area" at 100 mi/hr, you do the same thing:
>
> 300 * 391/100^2 = 11.7 square feet.
>
>
>
> ----
> A note about wind load ratings..
>
> For many towers, the tower itself has more area than the antenna. This is
> especially true for home TV antenna type towers which can't take very much
> antenna at all.
>
> Since most of the load on the tower is from wind pushing on the tower, as
> opposed to the antenna, my example of the equivalency of winch cable and
> wind load isn't quite right. Your evil neighbor will have to pull MUCH
> harder to pull your tower down, than the few hundred pounds rated antenna
> wind load.
>
>
>
> ---------- Forwarded message ----------
> From: Steve London <n2icarrl@gmail.com>
> To: towertalk@contesting.com
> Date: Thu, 27 Oct 2011 09:33:48 -0600
> Subject: Re: [TowerTalk] Equivalent wind load to square ft
> > A friend of mine is thinking of putting up some wind generators and has
> > asked for my advice. The only information he can give me for the wind
> load
> > is 300# at 100 MPH. I know that makes sense to some, but I'm used to
> square
> > ft loads for ham antennas.
>
> 100 MPH is 40 lb/ft2 . That would make his 300#/100 MPH load 7.5 ft2 .
>
> 73,
> Steve, N2IC
>
>
>
> ---------- Forwarded message ----------
> From: Alan NV8A <nv8a@charter.net>
> To: TowerTalk <TowerTalk@contesting.com>
> Date: Thu, 27 Oct 2011 11:47:37 -0400
> Subject: [TowerTalk] Hardline on a crankup? Was:Solid center conductor
> LMR400 for crankup tower?
> LDF4 or other hardline is flexible enough to use on a crankup tower? I'd
> wondered about that. What do others think?
>
> 73
>
> Alan NV8A
>
>
> On 10/27/11 12:03 am, Grant Saviers wrote:
>
> <snip>
>
> 9913-F7 is almost identical to LMR400 so why not use it or BuryFlex for
>> the up the tower run? For 2m, 70cm and higher it might be worth playing
>> with LDF4 or bigger.
>>
>
>
>
> ---------- Forwarded message ----------
> From: chris casey <cscvrp@gmail.com>
> To: towertalk@contesting.com
> Date: Thu, 27 Oct 2011 12:22:58 -0500
> Subject: [TowerTalk] guy detach in the middle?
> So the university club station I'm associated with needs to lean over
> their tower and do some antenna maintenance. The issue is in today's
> climate for someone to walk down to the corner of the sloped roof 2.5
> stories up and undo the turnbuckle of one guy doesn't appear to work
> anymore. Last time this was done in '97 I just went and undid it,
> redid it, no big deal, but times change. The other 2 guys are
> accessible.
>
> We are faced with some sort of man lift operation with the cost and
> logistics that come with such a thing it appears. We are morning or
> self sufficiency.
>
> What we do have is a head high passage of the guy from the corner of
> another roof as the base of the tower is not at the highest level of
> the roof. There is an insulator there within reach, so the guys
> continuity is broken at that point. What I'm wondering is if there is
> a way to open that joint that's reachable from that mid roof and put
> in a serviceable joint for this need? Simply undoing the cable clamps
> would get it open, but I don't think we would have a chance at putting
> it back, I'm pretty sure we wouldn't have any chance.
>
> The guy isn't tensioned well, I can easily move it several feet at
> this mid point that's reachable. Its guying a 50' stand of rohn 25
> which is anchored to the wall of the shack about 10-12' up. TH7 I
> think on top and a repeater antenna. Its not something I want to climb
> and probably couldn't get permission and maybe not even forgiveness. I
> want it down so the kids can get hands on with servicing everything
> anyway.
>
> Seems to me a turnbuckle is whats needed, but for that to be out in
> the middle of the span certainly isn't something I've seen before but
> I haven't seen it all. Is there any ideas out there? I'm well aware
> the best option is to deal with the end and its turnbuckle, its just
> going to be a lot easier if we can manage this on our own schedule if
> possible. We are a club on life support and with no revenue, so we are
> squarely in DIY mode as much as possible.
>
> Thanks.
>
> --
>
> -Chris
>
>
>
> ---------- Forwarded message ----------
> From: Pete Smith <n4zr@contesting.com>
> To: "Joe Subich, W4TV" <lists@subich.com>
> Date: Thu, 27 Oct 2011 13:36:11 -0400
> Subject: Re: [TowerTalk] Tower Base Round or Square?
> Sorry Joe, but Rohn 45G and "pier pin" adds up to a guyed tower to me.
>
> 73, Pete N4ZR
>
> The World Contest Station Database, updated daily at
> www.conteststations.com
> The Reverse Beacon Network at http://reversebeacon.net, blog at
> reversebeacon.blogspot.com,
> spots at telnet.reversebeacon.net, port 7000 AND now
> at arcluster.reversebeacon.net port 7000
>
>
>
> On 10/26/2011 7:47 PM, Joe Subich, W4TV wrote:
>
>>
>> > Does this apply to a guyed tower?
>>
>> Our discussion was about towers in general ... there was no mention
>> of guyed vs. self-supporting or single pier vs. multiple pier (e.g.,
>> Rohn SSV with its wide base).
>>
>> In any case, looking at the Rohn web catalog will show that CB1G is
>> specified for all heights of Rohn 25 - except the tallest at 110 MPH.
>> Two guy anchors are used in the three tallest 110 MPH designs and
>> those towers are specified for GB2G. CB1G is a 2' 6" x 4' 0"
>> square base ... CB2G is a 3'0" x 4' round base. The Rohn document
>> is quite emphatic that CB1G *must* be square.
>>
>> The trends are consistent in the 45, and 55 documents as well -
>> CB1G may be used for the shortest towers but must be square. Larger
>> round piers are specified for taller towers and those with higher
>> wind ratings. Even the smallest of the 65 towers start with CB2G.
>>
>> 73,
>>
>> ... Joe, W4TV
>>
>>
>> On 10/26/2011 5:21 PM, Pete Smith wrote:
>>
>>> Does this apply to a guyed tower? I can understand big overturning
>>> forces in a self-supporter, but most of the forces acting on a guyed
>>> tower base are vertical, aren't they?
>>>
>>> 73, Pete N4ZR
>>>
>>> The World Contest Station Database, updated daily at
>>> www.conteststations.com
>>> The Reverse Beacon Network at http://reversebeacon.net, blog at
>>> reversebeacon.blogspot.com,
>>> spots at telnet.reversebeacon.net, port 7000 AND now
>>> at arcluster.reversebeacon.net port 7000
>>>
>>>
>>>
>>> On 10/26/2011 5:10 PM, Joe Subich, W4TV wrote:
>>>
>>>> I asked the same question of a well known Professional Engineer a
>>>> couple of years ago. His answer was quite simple and made a lot
>>>> of sense ... the round base can be used instead of a square one
>>>> if the diameter of the round base is the same as the *diagonal*
>>>> measurement of the square base.
>>>>
>>>> In your case, for a 2' 6" (30") square base the round equivalent
>>>> would be 42" diameter *not* 36" as you propose. The reason has to
>>>> due with projected surface area - the area that resists overturning
>>>> - not volume (or weight) of the concrete.
>>>>
>>>> 73,
>>>>
>>>> ... Joe, W4TV
>>>>
>>>>
>>>> On 10/26/2011 1:28 PM, Richard Thorne wrote:
>>>>
>>>>> I'm finally getting some dirt work done in the next day or two at my
>>>>> new
>>>>> place which will include holes/concrete for my 45g tower.
>>>>>
>>>>> I plan on using a pier pin install, so does it matter if the base is
>>>>> square or round? The rohn book calls for a 2' 6" square hole 4' deep
>>>>> (I'm designing the tower based on 90mhp winds with a height of 120').
>>>>> It would be easier to use a 36" auger to dig the hole. Since I'm going
>>>>> with a pier pin I don't see that there would be any twisting moments on
>>>>> the concrete base, it would only be there to hold the tower up. But
>>>>> I'm
>>>>> not an engineer, hence the question.
>>>>>
>>>>> Thanks
>>>>>
>>>>> Rich - N5ZC
>>>>>
>>>>>
>>>>> ______________________________**_________________
>>>>>
>>>>>
>>>>>
>>>>> ______________________________**_________________
>>>>> TowerTalk mailing list
>>>>> TowerTalk@contesting.com
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>>>>>
>>>>> ______________________________**_________________
>>>>
>>>>
>>>>
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>>>
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>>
>>
>
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