Ladies and Gentlemen,
I ask for a "cookbook" method raising large antennas several weeks ago.
This is a summary of my cookbook with some notes, options, opinions and
addendums. Credit is given where credit is due, even if it is not original
but experiential. This might not be exhaustive or even clear, but it sure
helped me envision how I am going to put up the TH6DXX this spring.
E-mail your comments to k0wa@southwind.net, but don't include all this
information in the reply. Don't take up the bandwidth.
Raising a Beam to the Top of the Tower
1. Place a rope or steel cable (see notes) from the top of the mast to a
solid connecting point away from the tower. This is called a tram line. If
you use a tree, make sure it is healthy. Don't tie on branches, but onto
the trunk. In Kansas, make sure it isn't a Cottwood because it will fall
over. You can also use a pickup truck bumper. (Make sure you untie the rope
before you leave.) I have also used steel posts (any farm store has these)
and cut them in half with a torch. Pound two in the ground, one behind the
other and attach the line to the first and backstay the front to the back
with appropriate rope or cable. Tensioning the tram line is important, but
many people have diferent opinions. (See the notes.) Caveate Emptor (Or
something like that)
Note 1-A
What may have been missing from your description, Lee, was that the
tram line which supports the antenna on the way up should NOT be very tight.
Dave Robbins, K1TTT (ex KY1H) wrote an article for the YCCC Scuttlebutt a
few years back which analyzed the physics of this arrangement. Among other
things, he found that the lateral force at the top support (tower/mast)
GREATLY increases when the tramline gets taught and straight. It is MUCH
less stressful on the whole affair to let the tramline have a bunch of sag
in it.
If there is any question about the strength of the top support, I'd
recommend using a temporary back guy, from the top support to a solid
attachment on the ground, running 180 degrees around the tower from the
tramline bottom.
I can personally attest to these affects. I was using a schedule 80
water
pipe as a mast, and put a slight bend in it while raising a KT-34XA with too
tight a tramline and no backguy.
Tramlines are cool. It takes all day to set them up properly and
another to
take them down. But when they work right, I've been able to install large
antennas with no more ground crew than the XYL.
Think through your arrangement carefully, visualizing each step in the
process. This will help you remember details like 'the lifting line goes
OVER the boom' etc...
-Tony, K1KP, fisher@hp-and2.an.hp.com
Note 1-B
Lee, Depending on the height of your mast above the tower you may not
want
to attach the rope to it, lest you bend or break it. If you think about
it,you put an enormous sideways force on the mast when trying to raise a
heavy beam with the supporting (tram-line) rope reasonably taut. One
option is to attach the tram-line to the top of the tower (always assuming
it can handle the sideways strain) and use a come-along and/or a gin-pole to
get the beam to the right height on the mast. Alternatively, you can use a
second rope in the opposite direction to the first (suitably secured of
course) to serve as a back-stay to relieve the sideways strain imposed on
the mast by the tram-line rope. In my experience, it is best if you can
attach the tram-line to a point a good bit higher than where you need to
attach the antenna. You can then operate without the tram-line rope being
too taut, and once you have raised the antenna almost all of the way up the
tram line, slacken it to allow the antenna to come in to the right place.
While pulling the antenna up the tram line with a tractor has much to
commend it, you need to have a person on the tower to watch that the pull
rope, where it is tied to the load, does not reach the pulley through which
it is being pulled! My tractor could not sense the increased strain when
this happened, and the rope broke allowing a 6-element 20-meter beam (60 ft
boom) to slide back down the tram-line and,on reaching the ground, turn
itself into a prettzle!
-John N3HBX.
Note 1-C
The tram line needs to be somewhat tighter as the beam approaches
the tower, other wise you'll get fouled up with the last set of guys. My
approach is to tighten the tram reasonably tight to start with so by the
time the beam gets halfway up the stretch makes it quite loose. That's if
I'm using 1/2 inch rope. On bigger stuff 5/16 ehs is used, stretch isn't an
issue then. Regardless, too much tension when the beam is in the middle
2/3rds certainly does cause a lot of side pull on the mast. A back guy is
always a good plan, a bent mast is a real hassle. We use those 4000 lb
rated cable pullers to tension the tram, and once the beam gets near the
tower we just tighten the tram, the beam is lifted away and you
can the tram the beam right to its' resting place. On bigger beams (like 3
el 40 fullsize 400 lbers) the tram is usually attached the tower, not the
mast. Once the beam is trammed up next to the tower, a chain fall type of
hoist is used to pull the antenna vertically up into place.
-Don VE6JY is Don Moman email: ve6jy@freenet.edmonton.ab.ca
Note 1-D
I think you've got the basics down pat. It's really a lot simpler
than it sounds. Just a few small points.
I recommend wire for the tram line instead of rope. 3/16" guy wire
works great for me. Also lets me use old guy grips for attaching to mast,
etc. Use a come-along to tighten tram line (of course, not TOO tight).
Make sure the tram line ground attachment point is beyond the radius of the
guy wires.
-James / k1sd (ex KD1NG)
Note 1-E
An elegant alternative to a separate backguy is to use one continuous
cable
that passes through a pulley/sheave at the mast. That way, the forces are
roughly equalized at the mast and you only have to deal with one cable.
Either method does work and is highly recommended for medium sized projects
and up. Two other nifty facets are 1) you can raise the antenna part way up
the tramline while dangling a temporary feedline to it for initial testing.
And 2) the antenna can be lowered quickly for tuning adjustments or
installation problems and raised again in a matter of minutes. This would
include having a tag line hung up on the antenna, etc. You can lower it and
raise it back up again in 5-10 minutes. Like any similar job, it's the
rigging that takes most of the time.
Again, if anyone is interested in an illustrated article on installing
yagis including tram systems, an SASE to TOWER TECH, Box 572, Woodinville,
WA, 98072, will get you a free copy. BTW, Tom Schiller, N6BT and Force 12,
has written a book called "Array Of Light" and he has a chapter on
installingyagis. His methods are sell suited for limited space projects
where you may not have room for a tram line (sneaking the beam around guy
wires, etc.). It's $10.00 from Force 12 and an interesting read of Tom's
extensive tower and antenna knowledge.
-Steve K7LXC
Note 1-F
I think you've got it down just fine! I prefer to use a piece of steel
guy
wire (3/16-inch or 1/4-inch) or wire rope (only because I have oodles of
it, 1/4-inch) as a catenary in place of the supporting rope. This can be
tightened more than rope (but you may need a back-stay in the opposite
direction if you attach it to the mast on the tower) if you need the get the
yagis up higher (such as over a house, tree, etc.) Use a turnbuckle if you
want to get it real tight (but don't make it tighter than you would a guy
wire). Using this method I have single-handedly raised and lowered beams as
big as a 204BA (and recently I lowered a Cushcraft 5-el. 20m) without any
problems. If you must do it single-handedly (not preferred but sometimes
necessary!), here's my method to raise a beam:
Install the supporting catenary as you describe and raise the beam so
it is
just a foot or two below the mounting point. Tie off your pullling rope at
the bottom of the tower. Then loosen the catenary at the ground end and walk
it toward the tower and leave it there. The beam will now be laying against
the tower or mast instead of hanging out away from it on the catenary. Climb
the tower and use a small block-and-tackle or come-a-long to pull the beam
into final position. Reverse the procedure if you're removing a beam.
-Jon AA1K
Note 1- G
Lee, your method as described says: "rope" and "string". That will not
work! It requires Steel-rope for the tram/pulley arrangement and "rope" (I
use 1/2 inch poly) to pull the antenna up the tram cable.
The steel tram cable needs to be significantly tensioned to support
even a
medium size beam to a reasonable height. I tensioned my tram cable (3/16
stainless steel rope) to 1000 Lbs tension (as measured with a LOOS tension
gague) to haul up my 40-2CD to 67 ft. Tensioning to anything less sagged
too much to pull the antenna up!!
So, you see, that's why I say you can't (shouldn't) use a (non-steel)
rope
for the tram in you description. And the forces on the pull line are also
significant. I use the 1/2 inch poly and pull it with a tractor!
All this is on tape, and, as I have offered, I will send you (and anyone
who requests it) a copy of my tapes, for the cost of the tape and
shipping/duplicating expenses.
I have already received many many requests for the tapes. I am in the
process of buying blank tapes, determining the shipping costs, and the
duplicating costs. I plan to incorporate all three videos on one tape for
all of you. Once I have this done, I'll send all who responded to my offer
an email with the cost.
If you haven't sent me an email requesting copies of the tape, please do
so. Once I tell you the cost, and I'll ship you a copy once I get your check.
-Bill, N3RR
Note 1-H
I used 1/4 EHS for the tram line to pull my 402CD up to 83 feet. I ran
the
tram "way" out from the tower and ran it around a 6 inch wooden fence post.
I pulled like blazes on the "dead end" (the end coming back around the post)
and then performed some gymnastics while I clamped the dead end to the live
end with 2 cable clamps all the whilst attempting to maintain as much
tension on the cable as possible.
I ran 1/2" rope through a pulley at the bottom of the tower up to a
pulley
muffler clamped to the 4130 2" mast and down to the antenna. I pulled it up
by hand, reclimbed the tower and bolted the antenna on the mast. I'm more
brawn than brains, but it worked quite nicely.
I did pull it up and down several times snagging the elements in the top
guys before I remembered a concept called "tag lines." I wrapped some
closeline rope loosely around the forward most element end (one end only)
and loosley taped it to the element. It worked perfectly allowing me to
steer the element out of the way of the guys. I held the antenna haul rope
with one hand and the tag with the other. Just as I got it in perfect
position and started to ponder how hard it was going to be to get the tag
line freed, the tag line fell off. Perfect!
I live out in the boonies and did this solo. It would be a lot easier
with
some help, but I was surprised at how well it worked. I used a HY-GAIN boom
to mast clamp and other QHS (NL) mods have been done to my 402, but it still
only ways around 65-75 lbs.
-Matt-K7BG
Note 1-H
I've used both steel wire-rope and good regular rope for the tram line.
I
tend to favor the regular rope for the following reasons: 1) Easier to work
with. 2) Non-metallic; SWR check can be done on the antenna while hanging
from the tram line.
A good 1/2" braided rope like Yale Double Esterlon has very little
stretch,
and a tensile strength of 10,000 lbs. Highly recommended for all tower work.
Yes, keeping the antenna above the top guy can be a problem. The method
I've settled on, in most cases, is to run the tram line directly above the
top guy in one direction, tension it, and then drop that top guy (letting it
hang straight down the tower). The tram line takes the place of the guy wire.
As soon as the beam reaches the tower, the guy wire is reattached, the
tram
line is removed, and the beam is raised the rest of the way.
-Steve Maki K8LX
2. Install two pullies on the rope. The pullies will be used to harness
the beam to the tram line.
3. Move the antenna under the rope and secure it to the lower pully on the
rope. The boom should be perpendicular to the rope. Make sure that the
boom to mast clamp is facing the right direction. The antenna should be
tied to the balance point. You should use a harness that can "balance" the
antenna on the rope. By doing so, you will not need to use tag lines. Make
sure once the antenna is in place you can remove the harness ropes from the
boom.
4. Attach and 3 to 4 foot arm on the boom parallel to the rope using a
U-Bold. At the outer reach or the arm attach the second pully. You now are
supported by two pullies. The reason to put the arm on the boom to act as a
lever and keep the antenna from rolling over or flipping while raising the
antenna. It cannot flip over with this arraingment. (See the Option
below) I like Pete's method. Remember, I have not done this yet, but I
think it would work better of the "tiller" is away from the tower so you
don't have to take it off before you attach the beam to the mast.
Option 4-A
The arm should be down-wire from the boom, not up-wire, so it won't get
in
the way when the antenna arrives at the mast. Not only does the "tiller"
keep it from flipping, it enables you to pre-position the antenna with
element tips high, so that when it arrives at the tower they won't get
fouled in the top guys. Preferable way is to use a two-point harness tied to
the boom at equal distances on either side of the balance point, as far
apart as you can reach to untie while at the top of the tower. That way,
the harness tends to keep the boom horizontal. If you secure the tram wire
at the right height (far enough) above the point on the mast where you want
the boom to wind up, you can use the play in the
2-point harness to push/pull the boom over against the mast.
-Pete Smith N4ZR
5. OPTIONAL: Tag lines. A tag line can be place on each end of the boom
to keep the antenna horitontal during lifting. Tag lines are very long
loops of rope which can be taken off after the antenna is in place. Smaller
rope or cord could be used for the Tag Lines I think most people hate tag
lines. I have not riggedthis before, but I think making a harness which
balances the antenna correctly, along with the tiller concept would allow
for smooth raising of the antenna with a minimum of ground crew.
6. Place a pully at the top of the tower and place a pull line through the
pulling and attach it to the arm on the boom of the antenna. The pull line
rope then goes to the ground.
7. Slow pull the antenna up the rope until it comes to a place where you
want to attach it to the mast. A person on the ground might have to loosen
the tram line to allow the placement of the antenna on the mast. I suggest
that a "hay-knot" be used at the lower end of the tram line to insure that
the rope doesn't get out of hand.
Note 7-A
Another trick is to use a pulley/snatch block at the bottom of the
tower
so that the haul rope goes horizontal for easier pulling as opposed to
pulling down. A down pull is all arm strength whereas with a snatch block
you can put the rope around your waist and just back up.
-Steve K7LXC
Option 7-A
I envision that one could have a gin pole set on the tower with the tram
line tied to the tower and not to the mast. If your mast and rotor could
take the sideways pull with a back-stay that would be fine. You would then
have a the tram attached above the point at which you were going to install
the antenna. All you would have to do is to swing the antenna over to the
mast and bolt it on.
But, one could attach the tram line to the top of the tower or below the
attachment point, pull the antenna to that point, attach the gin pole rope
to the antenna, loosen the tram harness and drop the tram, and then raise
the antenna in place on the mast. A little more complicated, a little more
rope, but would not place burden on the mast and rotor and would be less
rigging time.
-Lee K0WA
Addendum 1 (Not exactly what most people have - at least not the guys I run
with)
Lee, Here is the antenna lifting arrangement we use at NK7U to lift monster
beams. This arrangement has been used to lift 20M6's (60ft booms), 20M5's,
40M4's, etc. 2 towers are needed to do this however.
1. A large pulleys is needed at the top and bottom of both towers.
2. One rope is run from the ground, through the bottom pulley, up through
the tower, to the top pulley and then back down to the ground at a point
between the 2 towers
3. The same is done with second rope on the other tower. The ropes will
then form a "M"
4. The top of our boom to mast plates have 2 holes drilled into the corners
to accept a yoke. The yoke is attached to the plate with 2 snap links.
The top side of the yoke is attached to the ends of the 2 ropes. A photo
of this setup can be found on our home page at:
http://netnow.micron.net/~jcullum/image/joe20.jpg
5. A tag line may be used to keep the antenna from rotating.
6. At this point you are ready to lift. Actually it is more of a pull since
you are pulling horizontally against the bottom of the tower. We use a
4-wheeler on the side that the antenna is going to. And the other rope
has 2 people on it. The antenna can be lifted straight into the air, past
the guys and then swung into the tower at the appropriate spot. Multiple
beams can be installed up and down the tower without ever having to move
the pulleys.
A benefit of this arrangement is that the antenna can be lifted quite a way
off the ground and swr measurements can be taken. Getting the antenna back
onto the ground is only a matter of releasing the ropes (carefully). You
can also pull the antenna up 50 ft or so and use a tag line on the
reflector to point the antenna straight up for more accurate (?) swr
measurements.
Other photos of the antenna installations can be found on our home page at:
http://netnow.micron.net/~jcullum/html/nk7u.htm
-Jim K7MK jcullum@micron.com
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