M2 Antenna Systems 12M4DX Manual - 12M4Dx Assembly Manual
Note: A cup of zinc paste (PENETROX, NOALOX, or equivalent) has been provided to enhance the
quality of all the electrical joints in this antenna. Apply a thin coat wherever two pieces of aluminum
come in contact. It also works well to prevent the stainless nuts from galling on the bolt threads.
1. Refer to the Dimension Sheet. Note the different boom sections and the approximate position of
each element. Slide the 2” RING CLAMPS into their approximate positions on the boom sections. For
example, the rear boom section has two 2” ring clamps, one located at 1” from the rear end (with no
boom assembly holes) and one about 11” from the swaged end. Note this section may have a 5/16”
hole for an eyebolt - the other two 2” x 84” swaged sections are identical. Accurate positioning is
unnecessary this point. Spread the ring clamp fingers with a flat blade screwdriver to ease movement
on boom. Loosely add a 1/4-20 x 1” bolt and locknut to fingers of all clamps.
2. Assemble the boom using 1/4-20 x 2-1/2” bolts and locknuts. Tighten all joints. If possible lay the
boom on a flat surface (cement floor or driveway). Start with the REFLECTOR ring clamp. Rotate it so
its long flat surface is down and 1” from the end of the boom. If your boom has EYEBOLT HOLES,
rotate the boom so the eyebolt holes are aligned straight up. Tighten the 1/4-20 x 1” bolt in the ring
clamp locking the ring clamp in place. Now measure, mark and tighten the 3 remaining ring clamps in
place. REFER TO THE DIMENSION SHEET FOR THE EXACT RING CLAMP / ELEMENT SPACING.
Final alignment may be necessary when all the elements are installed on the RING CLAMPS. Now
turn the boom over and place it on a table or workmate for element attachment.
3. DRIVEN ELEMENT ASSEMBLY: Select the two 3/4” x 5’ (60”) element sections with 2 small holes
at the butt and attach the two short 1” x 12” swaged tubes using 8-32 x 1-1/4” screws and locknuts.
Now locate the 2 x 4” balun mounting plate and drop 2 1/4-20 x 2” bolts through the outer holes.
These same bolts then go on through the inner holes in the 7/8" x 15" CENTER FIBERGLASS
INSULATOR ROD. Set this insulator/plate assembly on the DRIVEN ELEMENT ring clamp, sliding the
extended bolts down through the holes in the ring clamp, add the nuts and tighten.
4. Slide a poly disc on each end of the fiberglass rod all the way down to the ring clamp. Mount the
balun on the plate using the 2-1/2” U-bolt and cradle. Face the connector towards the Boom to mast
plate. Position the balun so it’s leads will reach out to the outer holes in the fiberglass rod insulator
and tighten the U-bolt lightly.
5. Now slide the 1” element butts onto each side of the insulator and align the holes. Push a 1/4-20 x
2” bolt UP through one holes, add two machined HAIRPIN CLAMP BLOCKS face to face over the
stud. Place a balun lug over the stud and add a locknut finger tight. Add the second bolt in the same
fashion. The HAIRPIN TUBES ASSEMBLY will be added later.
6. PARASITIC ELEMENT ASSEMBLY: Pair up the remaining 3/4” x 60” element sections and 7/8” x
30” sleeves. Slide the 3/4” sections into the 7/8’ sleeves. Align the holes and add the 1/4-20 x 1-3/4”
bolts. Set this element assembly onto the ring clamp and add the nuts. Tighten securely until the 3/4”
inner section is tight.
7. ELEMENT TIPS: Refer to the DIMENSION SHEET and install the tip pairs as shown. Secure with
5/8” compression clamps (SEE COMPRESSION CLAMP & TIP ASSEMBLY DETAIL) sheet.
8. Install the 5/16” x 4” Eyebolts into 5/16” holes in the rear and front boom sections. The boom to
mast plate may be added loosely at this time as well.