M2 Antenna Systems 20M4DX, Assembly Manual

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Note: A cup of zinc paste (PENETROX, NOALOX, or equivalent) has been provided to enhance the
quality of all the electrical joints and make assembly and disassembly easier. Apply a thin coat
wherever two pieces of aluminum come in contact. Use it also to lube the stainless screws and bolts.
REFER TO THE DIMENSION SHEET FIRST. YOU MAY BE ABLE TO ASSEMBLE THE ANTENNA
REFERRING TO THE WRITTEN INSTRUCTIONS ONLY AS A GUIDE.
1. BOOM ASSEMBLY: Note the different boom sections and the relative positions of each element.
ALSO NOTE THAT TWO BOOM SECTIONS HAVE LARGE EYEBOLT MOUNTING HOLES. Begin
by sliding the INNER TWO 2-1/2” RING CLAMPS into position on the appropriate boom sections.
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. Add 1/4-20 x 3” bolts and locknuts to each joint
and tighten securely. Add the eyebolts and secure with 5/16 nuts and lock washers.
2. Return to the first boom section from the rear. Position the 2-1/2” ring clamp ABOUT 81” from the
un-swaged end. This is the DRIVEN ELEMENT and ALL spacing dimensions are referenced to it.
Orient the ring clamp so it’s long grooved top is perpendicular to the EYEBOLT HOLE just to the rear
in the first section. Tighten the 1/4-20 x 1" bolt and locknut to hold the clamp in position.
3. Refer to the figure “DRIVEN ELEMENT ASSEMBLY.” Push two 1/4-20 x 2” bolts through the small
holes in the 2 x 5” BALUN MOUNTING PLATE. Now feed these bolts down through the inner two
holes of the 7/8 x 30” fiberglass rod. Mount this assembly onto the ring clamp holes and add the
locknuts to the underside of the ring clamp. Tighten securely. Then push on a 2” diameter white
POLYETHYLENE RING on each side tight up against the ring clamp. These rings for a long path to
prevent water and residue induced arcing.
4. Select the two 1” x 60” element sections with 9/32 holes 1” in from the butts. Slide them onto the
the 7/8” dia. fiberglass rod, align the holes and add the 1/4-20 x 2” bolts so the threaded ends protrude
upwards. Add a non-locking nut to each side and tighten loosely for now, forming a threaded stud.
(The balun leads will attach to these studs later on).
5. Locate and mount the 1-1/4 x 60” element section with both ends swaged to fit 1” tube. It is the
center section of the REFLECTOR element. Use two more 1/4-20 x 2” bolts and locknuts. Tighten
securely. Now add the 1” x 60” tubes with the two small holes at the large end. Secure these to the
inner section with 8-32 x 1-1/2 screws and locknuts. Tighten the screws alternately until each joint is
secure and further tightening becomes difficult.
6. Pair up the remaining 1” inch element sections and slide the butts over the 7/8” x 30” sleeves. Align
the holes and mount to the ring clamps using more 1/4-20 x 2” bolts and locknuts.
7. Assemble the rest of the element halves using the 8-32 screws, locknuts and compression clamps
see DIMENSION SHEET and COMPRESSION CLAMP & TIP ASSEMBLY DETAIL SHEET. Tighten
each joint securely by alternating back and forth between the two screws at each joint until no
movement is noted. BE SURE TO PAIR UP the 3/8” tip sections. DETERMINE YOUR CHOICE OF
BAND SEGMENT. INSERT TIPS TO CHOSEN DIMENSIONS AND SECURE USING
COMPRESSION CLAMPS.
8. Now adjust
ELEMENT SPACING following the Dimension Sheet. Since the Driven Element is
fixed, use it as the primary measurement reference. Dimensions given are “center to center.” After
setting spacing, align elements with the Driven Element and tighten the 1/4-20 x 1” bolts at the bottom
of each ring clamp.
20M4DX ASSEMBLY MANUAL