Revised 14 June 2003
8
6. With one element mounting plate held level, using a small bullet level, check level on
the other plate.
7. Twist one plate with respect to the other by grasping them and turning in opposite
directions about the long axis of the boom. Now trial-tighten the twelve quarter-inch
bolts, 4 in each of the two boom coupling sleeves, and 2 in each of the two element
mounting plates, and recheck the level.
8. When the plates are mutually leveled, or as nearly so as you can get them, finish
tightening the 1/4” diameter bolts. Do not tighten enough to distort the boom tubing
out of round. Just touching the tubing, then another half turn would be fine.
ATTACHING THE HAIRPIN ASSEMBLIES
1. Attach the hairpin assemblies with 1/2 inch clearance between the insulating blocks
(at the very end of each hairpin) and the boom-to-element mounting plate using the
stainless hose clamps provided. Red markings indicate the location of the clamp
strapping over the hairpin supports.
2. Install the copper straps to the hairpin assembly as follows:
a) Apply silicone grease to both sides of the smaller (3/16”) hole end of each copper
strap.
b) Fasten the copper straps to the welded tab at the end of each hairpin tube.
The order of hardware for the 10-24 stainless screws in the insulating block is as
follows:
1) The head of the screw is on the side of the insulating block that is closest to
the element mounting plate.
2) The screw goes through a flat washer, finish side to the plastic, except for one
screw that passes through a ring terminal, then through a flat washer, finish
side to the plastic.
3) Each screw then protrudes through the plastic block and the welded tab.
4) After the tab, there is a fender washer, copper strap, fender washer, split ring
lock washer, and a nut.
Note:
The copper straps must leave the insulating block parallel to each other
and dressed straight up away from the boom. When the boom assembly is
finally rotated into operating position, with the element mounting plates and
hairpin assemblies below it, these straps will be pointing straight down.
After the elements are attached to the boom in a later step, the straps will
be bent toward the element with a gentle large radius bend to attach to the
element feed points.
3. The larger (1/4”) hole end of each will be similarly greased and captured between
fender washers on the bolts that are the feed point connections for the antenna
element. This will be done after the elements are attached to the boom in a later
step.
