Hi Grant,
I think the guys will be in the way of the bucket... I had been focusing on
safety and how do you 'hold' the antenna and hadn't thought about proximity
to the guys ... I think I'll forego the bucket and just do it the old
fashioned way. I've done that before and it wasn't a problem.
As for direction - the last time I used a crane I had 10' separation minimum
between antennas and there wasn't any issue with getting the crane in there
... This time its worse case 11' for one pair and much more than that from
there on down. There will be the 20 at 135' already mounted to the tower so
the first antenna below that is the 40 at 124' so that's 11' separation with
a good deal of room out to the closest elements on either antenna ... then
we're at 90, 75, and 45 - LOTS of separation. So for me it seemed only
logical to go from the top down. Also there is the thinking that if time ran
out it would be easier to tram the lowest antenna as a last resort. All the
elements are clear of the tower of course since they have to mount to it.
The closest one is probably 3' away so I don't believe that will be a
problem.
Guy tension - the rated tension on 5/16" guy cable is 1100# - that's what
I'm going by. 600# is - I believe - really low on 21K guys - that means I'd
think that it can sway more.
The crane is a 70 ton and able to go to 200' I'm told. The 6 sections of
tower with one ring and the guys will weigh about 800 - 850# so I'd sure
hope that isn't a problem! I'd hate to have to move that closer as its
already set up.
Also note on 'being ambitious' ... 2 of the antennas will be already
installed so with them its really the time it takes to mount that tower
section (one 10' with a 4' top piece) ... beyond that its 4 antennas... to
me that seems easy enough to do. I'd sure hope it can be done in 6 - 7
hours. If you figure an hour for each task: 60', guy tensioning, top piece,
4 additional antennas that is 7 hours. But I think the antennas are more
like 45 minutes a piece ... I should have 8 hours of solid sunlight after he
is set up (they said 30 minutes tops to set up which seems a bit short to
me).
g.
-----Original Message-----
From: Grant Saviers
Sent: Wednesday, October 12, 2016 1:20 AM
To: StellarCAT
Subject: Re: [TowerTalk] questions on the use of a man-bucket and guy
tensioning 5/16" EHS
I've done the "bolt antenna to the bucket" with a boom lift and
transferred it to the mast by myself. I made some 3x3" angle iron
brackets u-bolted to the bucket to hold a 40m yagi, u-bolted on top of
the angles. However, that rig is a lot more stable than a crane + cable
+ bucket. It seems to me that choker slings on the boom to get the
balance right and a good crane operator will make for an easier set by
the man on the tower. At least that is what was done for my tower. I
also think loading yagis from the bottom up avoids a lot of threading
around elements by the crane op. I've used the man bucket + crane rig
for repairs and that sure was nice to be able to work out on the boom.
The crane bucket was also much larger and heavier than a boom lift bucket.
With a 148' of tower, make sure the crane can lift 60' of R55 with two
rings (more than 2k#?), we were right at the limit with a double jib
extension and a 20' stick of R65 to 142' with two antenna rings mounted
and no antennas. It depends a lot on the crane set to base of the tower
distance and considering the crane needs to top out at 160' or so..and
then crane swing etc. Has the crane co been out to check out the site
and advise on right size crane? Rigging extension jibs also takes a
while by the crane op.
I have 20' EHS tails on the Philly, and assume you are doing this for
safety. Then a Klein grip on the EHS and tension dynamometer or gauge
bring the full guy to proper tension with a come along. Do this on all
guys and use a transit to measure tower plumb. Iterate to get plumb in
two planes and equal tension. Then mark the free EHS end for the
turnbuckle end, cut, add grip and attach to turnbuckle. Adjust
turnbuckle until dynamometer shows tension slacking off. btw 1100#
sounds like a lot of pretension for two or three sets of guys on R55.
My R65 two sets are at 600# with 21k Phillystran, but not a rotating
tower. What did the PE specify?
Trying to do the tower set and load 6 antennas in one day sounds too
ambitious, IMO.
Stay safe and be careful with fatigue of the on the tower man.
Grant KZ1W
On 10/11/2016 17:17 PM, StellarCAT wrote:
Hello,
This is directed at those that have had direct experience with the use of
a crane and a man bucket.
My antenna/tower project, at least the major part of it (one of the two
towers) is finally getting close to being done. I’ve ordered the crane for
the end of next week ... so I can get a man bucket for an additional $150.
There are 6 large yagis to be installed – well 5 and a rotary dipole for
80/75 which is also BIG in that regard ... there’s currently 74’ of tower
up on the K0XG rotating base and 2 rings ... I’ve built another 60’ of
tower with the second ring on it ... that will go up first and the top
section of guys installed.
then I have 14’ of tower that will already have mounted on it (I hope) the
rotary dipole at the top and a 5 element 50’ boom 20 mounted just above
the leg of the tower (R55). That whole assembly will go up as one and thus
2 antennas will be finished once this is bolted in to place.
Then there are 4 yagis to go up along the height of the tower from 124’
down to 45’. I had planned on just having a guy on the tower stuff (no
choice there of course) ... and then have him climb down the tower as we
go from the top down with the 4 remaining antennas 124’, 90’, 75’, 45’.
This means I’ll have to lash up the antenna on the ground to the crane
hook and then of course the crane will raise it up to him where he can
hopefully bolt it in place (2 plates on the boom already in place for the
boom to tower mount).
But the guy that is doing the climbing is saying the man bucket will make
putting the antennas up easier. Having never used one I’m writing to get
the comments of those that have used one.
How is the antenna ‘held’ to the man bucket? And whatever that is does
that get in the way of mounting the antenna when at the tower. I.e. you
have the side rails of the man bucket that would be ‘hitting’ the tower –
will the antenna ‘move in” to position and still be SAFELY held until
bolted in place?
Is it really any faster?
I assume it could be considered safer as the guy would be in the man
bucket and not climbing the tower but obviously one expects whomever that
is to be careful and always be strapped in when climbing ...
thoughts please?
And on another note: the top guys are 5/16” mixed with 11200# philly (50%)
... how much tension do you need to pull out of the ‘free’ cable before
attaching it to the turnbuckle? I’m worried about not pulling enough and
having to redo the big grip ... on the bottom set of guys (the bottom 2
sets are 1/4”) I managed to do just that – I pulled too much and had to
redo the big grip. Of course on the 5/16” the worry is more that I won’t
pull enough and will run out of turnbuckle adjustment space. Put another
way: how fast does the tension go up as one adjusts the turnbuckle? If the
turnbuckle has 12” range – will that pull up even a relatively loose guy
to full tension of 1100# before running out of adjustment room?
Gary
K9RX
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