6. BOOM ASSEMBLY: Inspect the CENTER BOOM SPLICE for any nicks or scratches. File smooth if
any found. Locate Boom Section (3” X 0.125” X 180”) swaged (1) end & Boom Section (3” X 0.125 X
180”) straight. Before joining boom pieces together, lightly oil or lubricate the COUPLING RINGS &
insert Boom Stiffener assembly into straight boom section. Insert Boom Stiffener assembly
approximately 17” from the end. Make note: This is end must be positioned to the rear of the
completed boom. This will center boom stiffener over the boom to mast plate (see dimension sheet).
Add final Boom Section (3” X 0.125” X 180”) swaged (1) end to complete boom. Secure all boom
sections using 1/4-20 x 3-1/2 bolts and locknuts.
7. Orient the eyebolt eyes to the top of the boom. Place the boom on bucks or equivalent to get it to a
convenient working height. Position one PARASITIC CENTER SECTION one inch from the end of the
boom, add the saddle clamps and the four 1/4-20 x 3” bolts (a dab of Noalox on the threads make
insertion easy). Align the top of the clamp to the eyebolt and tighten the saddle clamps evenly. Next,
refer to the DIMENSION SHEET and using a tape measure and a marking pen or piece of tape, mark
the ELEMENT LOCATIONS on the boom. Your choices are:
CW-LO
FONE FULL
BAND
REFL
0”
0”
D.E. 54.50”
61.000”
D1
116.00”
127.00
D2
323.00”
325.00”
D3
528.00”
528.00”
Dimensions represent the edge of the rear clamp block for each element. Now mount the center
element assemblies on the boom the same as the reflector. Align each with the reflector and tighten.
8. HAIRPIN MATCH ASSEMBLY: Refer to the HARDWARE ARRANGEMENT drawing. Insert a 1/4-20
X 2-1/4” bolt from inside the band clamp and Install the band clamp loosely positioned about 30” inches
in front of the driven element. Mount the BALUN using the 2-1/2” U-bolt and cradle but do not over
tighten. Remove the finger tight nuts over the hairpin clamp blocks and place the balun lead lugs over
the studs and replace the nuts finger tight. Next, slide the short bent end of the 3/8” tubes into the
small hairpin clamp blocks and flush the ends of the tubes with the blocks. Align and tighten the clamp
block bolts lightly. Install the shorting bar on the straight ends of the tubes and add the 1/4-20 x 1/4” set
screws, but do not tighten on to the tubes yet. Set to the proper shorting bar dimension, align and
tighten the set screws securely. Move the band clamp under the shorting bar, add the 3/8” spacer tube
on the stud and drop the shorting bar over the stud and add the locknut. Tighten the band clamp, and
then tighten the nut.. The dimension for your selected band coverage is:
CW LO FONE
FULL BAND
28.00”
31.500”
Refer to the DIMENSION SHEET. This dimension is from the inner edge of the shorting bar to the inner
edge of the tube. Install the main feedline or feed line jumper on the 1:1 balun. Tape the connector up
carefully. Use the large cable ties to secure the cable to the boom.
9. INSTALLING THE ELEMENT TIP SECTIONS: Start with the REFLECTOR tip sections and insert
each double wall 1” element butt into the 1-1/4” center sections. align the holes and insert the 8-32 x 1-
1/2” screws. Add the locknuts and tighten securely. Continue adding the other tip sections until the
antenna is complete.
20M5-125 ASSEMBLY MANUAL
