M2 Antenna Systems 40M4LLDD Assembly Manual Download

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19. Attach the BOOM TO MAST PLATE at the balance point, using the two large 3” U-bolts, 3/8-16
stainless lockwashers, and nuts. Align plate to vertical and tighten nuts. For they should be attached
in a way to allow the boom to be balanced on your tower / mast.

20. OVERHEAD BOOM SUPPORT SYSTEM.
A. Attach one end of the 5/16" Dacron cord to the rear eyebolt using two turns around the eyebolt and
a series of three half hitches or equivalent knots. Finish with about 6 inches of cord after the knots.

Without cutting the cord, do the same at the front eyebolt.

Pull on the knots

HARD

SET

them.

Seal ends with heat or flame to prevent fraying. Tape the excess 6 inches of cord back to main cord
tightly with black vinyl electricians tape.

B. TEMPORARILY insert a 2 inch U-bolt through the turnbuckle plate and add two nuts so about 1/2
inch of the threads stick out. Insert this assembly through the top set of 2” U-bolt holes in the boom to
mast plate from the boom side and add two more nuts. Open the two turnbuckles up until just

thread

or two

from each end shows

inside

the body of the turnbuckle. Hook the turnbuckles into the

holes at the edge of the turnbuckle plate. Equalize the Dacron cord over the plate and cut it. Take
two wraps of the cord through the eye of the rear turnbuckle, PULL the cord as tight as possible and
make the knots as before. Repeat for the front cord section and turnbuckle. Cut off any excess over
one foot long and again seal and tape back to the main cord.

C. Now DISASSEMBLE the U-bolt from the boom to mast plate. Before installation, if possible, install
a short temporary mast, attach turnbuckle, and let the overhead guy system support the boom
overnight. The Dacron cord DOES NOT STRETCH UNDER THIS LOAD but it's weave will take a SET
and the boom may droop just a bit. If your boom droops again following final adjustments, check your
knots. They may be may be slipping.

D. After final installation of the antenna, the turnbuckle plate, installed loosely with a 2” U-bolt, is raised
up the mast. When the boom is straight the U-bolt is tightened. This should place the turnbuckle plate
4 to 6 feet above the boom. Do the final boom straightening with the turnbuckles and safety wire to
preserve adjustments.

21. Check ALL hardware for tightness. Check ALL element sections, especially tip sections, for
correct placement. Make any final adjustments to linear loading tension.

22. Attach the feedline section to the balun. Route towards the boom to mast plate. Secure at regular
intervals with tape or nylon ties.

23. When mounting this antenna on a tower or mast with other antennas there may be interaction. In
general VHF and/ or UHF antennas mounted for HORIZONTAL POLARITY should be at least 40
inches above or below the antenna. Use good quality 50 Ohm coaxial cable to feed the antenna and
be sure your tower and rotator system can handle the wind loading and vertical weight of this antenna.