[TowerTalk] AB-621/G Military Mast

chetmoore chetmoore at cox.net
Thu Sep 3 22:57:49 EDT 2015


For what its worth,   I bought my 621  rocket launcher from K4TMC down in
Raleigh north carolina about 3 hours from my qth. It was not in a shipping
crate. I loaded the whole thing into my 1997 tacoma truck (this is the older
smaller Tacoma) the two of us Henry K4TMC and I  lifted and moved the base
near the tail gate of the truck.  Then lifted other end and slid it into the
bed of the truck.  Then we took all but two of the 8 tubes out of the tube
"case" and did the same thing Lifting one end to the tailgate and slid the
case on to the truck bed. Then we put the other 6 tubes back in the case.
All the other parts were in a heavy duty canvas bag which included 8 sets of
pre-cut guy wires, the top section of the 621 which is about two feet long,
Some heavy duty stakes to anchor  the base into the ground and four others
to be pounded into the ground for each of the 4 sets of guy wires.  My guy
wires are color coded there will be 4 white ones, 4 red ones and 4 blue
ones. The handle for the elevator was also in the bag along with a piece of
aircraft tie down cable which is used to help you  know how far out to pound
the stakes into the ground for your guying system.  When I got home I had a
neighbor help me get the base out of the truck and on to a dolly. I removed
6 of the tubes and was able to slide the tube case out of the truck myself.
As I remember the tube case with the tube in it does fit and is locked into
the base section bu in my case it was already detached and I have not seen
any reason to attach it. I have see some people stick the tube case under
the  last tube is elevated fully. This would keep the whole tube assembly
from coming down if the elevator brake were to fail but I have never done
that with mine. I have put this thing up for 3 field days, once at N4DLD's
qth for sweepstakes. It would be really helpful if you had someone who has
erected one of these at least once before. It is easily erected by 2 people
in less than 30 minutes.

I am assuming you got the instructions with it.  If you did not, its on the
internet and you should print them out.

2 warnings 

1.You can stand up the base and guy it at the top of the base but Do not
attempt to erect more than two tubes of this  tower if the wind is over 5
mph. don't crank it down in winds higher than 5 mph either. The 621 has
almost no stability until it is fully guyed.  Even more so if there is an
antenna and rotor affixed to the 621.

2. We put a sheet of plywood on the ground where the base was to be mounted.
I highly recommend this but it is not required. It makes it much easier to
get the base section  stood up and level.  Once we had the 621 stood up at 8
feet with the rotor on the mast mount we just dropped the antenna which
already had a short 3 foot piece of mast on it into the rotor.(this was done
using an 8 foot  step ladder to just set the beam in the rotor at about 9
feet) and tightened it down. Then we cranked it up guying it in two places
with the two guy rings provided.  We put it up for the ARRL DX CW contest
and it did really well.  I came home a couple of days after the contest and
saw that the tower was leaning a bit to one side.  It had rained and the
ground was soft.  I decided I would simply go to the side opposite to the
direction it was leaning and bring it back to vertical using the tensioner.
The guy wires have built in tensioners (same function as turn buckles).
When I tightened up the tensioner I heard a SUCKING sound as it pulled the
guy stake on the opposite  side S L O W L Y  out of the ground. I ran and
grabbed the guy wire and pulled it back holding the tower from falling. I
was unable to hold it and It slowly started to fall again.  I slowed its
fall and it slowly slipped (almost in slow motion) down on to A guy wire
from my 100 foot tower. No damage was done to the antenna or tower of guy
wire but it did take 3 of us and a come along to get it back to vertical
about an hour later.   Just be aware that if the ground is wet (in my case
"saturated" that the tensioners are strong enough to pull the guy stake
opposite to the one you are tightening. OUT OF THE GROUND.  If you are
making this a semi or permanent installation, I would use much larger
permanent screw in anchors.  Don't even think about using anchors like
people use for a dog "tie down" to guy this tower.

I made a permanent cement base for the 621. The base can be unbolted from
the bolts in the cement if I want to take it to field day etc.  The rocket
launcher remains most of the year on the cement base and we made a home brew
bracket to mount the base to the house as well.  I leave 2 tube sections in
the base which places the rotor
About 3 feet above the top of my roof (20 feet) with the antenna removed.
The antenna elements are removed from the boom And stored on my fence as is
the boom after the elements are removed.  The rocket base and tubes are
virtually invisible to all but my next door neighbor. The guy wires are
removed and kept in my garage.  From the time I decide to put the rocket
launcher back up for sweepstakes (go pvrc !!!) or need to test new antennas,
I just go up on the roof drop the boom into the rotor, attach the elements
which are removed from the boom but not taken apart. Connect the feedline
and in about 20 minutes (if there is no wind) the c4 is at 50 feet and fully
guyed (to permanent anchors) And ready for action.

The guy who designed the rocket launcher is a genius. We had 6 or 7 of them
at W3PP which stayed up full time for the ten years I used to go up there.
there is a kit which will extend  the 621 to 70 feet or higher. At W3PP we
had a 5 element 15meter beam on one,  a 5 element 10M beam on another,  A 3
Element 20 on another, A packet antenna at 80 feet on another.  Those were
all guyed with a 3 wire system  with large screw in anchors vice the 4 wire
system that comes with it.

I'm not sure what you plan to do with yours but I believe you will be a
happy camper once you get it vertical.
Some people who raise and lower theirs frequently it have fitted a power
drill to the replace the handle used to crank it up and  Down more quickly.
YMMV.

Press on regardless

73

Chet N4FX, KP4EAJ, KL7AIZ, N6ZO  KG4ZO, VQ9XX, ZD8W   VP2A,  N6ZO/HH9,
N6ZO/6Y5

-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of dw
Sent: Thursday, September 03, 2015 5:31 PM
To: towertalk
Subject: [TowerTalk] AB-621/G Military Mast


I have made the purchase of an AB-621/G mast from a surplus supplier.
The unit should arrive next week.

I haven't seen it up close yet, so I'm wondering how much I'll need to
disassemble it in order to be able to move it.
The shipping crate is close to 400lbs.
There are supposed to be 3 boxes in the crate.
So some of that weight will come out in separate boxes.
But the 8 feet long base section all by itself might weight close to 150
lbs.

Has anyone assembled or worked with one of these?
Thanks
N1BBR
--
 Bw_dw at fastmail.net

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