CUSHCRAFT BIG THUNDER Series, Manual

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Figure 9
Tuning Procedure
The X9 does not require tuning. The broadband VSWR characteristics of the log cell can not be improved by adjusting element lengths. Varying the
element dimensions from those suggested in this manual is not recommended. For help with tuning, please contact Cushcraft technical support.
48 Perimeter Road, Manchester NH 03103 USA • Telephone: 603-627-7877 • Fax: 603-627-1764 • E-mail: sales@cushcraft.com
Web Site: http://www.cushcraft.com • International - Tel: +1-603-627-7877 • Fax:+1-603-627-1764
COMMUNICATIONS ANTENNAS
7 - Boom Truss
Assembly
Frequency Coverage (Meters) 10, 15, 20
Total number of Elements 9
Maximum Gain (dBi) 20M 13.0 @ 14 deg
@ One Wavelength 15M 13.9 @ 12 deg
above ground 10M 14.0 @ 15 deg
Free Space Gain (dBi) 20M 8.25
15M 9.75
10M 9.75
Maximum Front to Back Ratio (dB) 30
Number of Elements per Band 4*
VSWR Minimum 1.1:1
VSWR 1.5:1 Bandwidth (KHz) 20M 350
15M 450
10M 1500
Longest Element, ft (m) 36.5 (11.12)
Turning Radius, ft (m) 21.7 (6.61)
Boom Length, ft (m) 28 (8.53)
Boom Diameter, in (cm) 2-1/2 (6.35)
Maximum Mast Diameter OD, in (cm) 2-1/2 (6.35)
Maximum Wind Survival, mph (kph) >100 (>161)
Maximum Wind Surface Area, ft
2
(m
2
) 9.9 (.92)
Windload @ 80 mph, lb (kg) 255 (116)
Maximum Power Handling (KW) 2
Weight, lb. (kg) 85 (38.5)
Design Safety Factor 1.25
* 6 active elements on 10 meters
SPECIFICATIONS
Figure 9 illustrates the boom truss assembly. Refer to
the boom truss assembly parts list for the hardware
required. The X9 uses Phillystran® cable to guy the
boom. The cable is one continuous piece from one boom
end to the other. Note the Phillystran cable safety loop
that goes around the mast truss bracket.
Attach the truss plate (26) to the mast 3 feet
(1m) above the boom to mast clamp using the
3/8" hardware provided. Position the truss bracket
on the same side of the mast as the boom to
mast clamp. Unscrew the turnbuckle ends until
there is 1/2" (1.2 cm) of thread remaining. Place the jaw of each turnbuckle (23)
into the holes of the truss bracket. Place a thimble (59) on the eye of each
turnbuckle. Place three loose cable clamps (24) onto the cable end. Reference
Figure 9 and place the cable clamp saddle over the load bearing cable. The load
bearing cable is the cable that attaches to the boom end. Feed the cable through
a turnbuckle eye. Run the cable back through the cable clamps. Place three
additional cable clamps on the end of the cable. Feed the cable through the other
turnbuckle eye. Run the cable back through the cable clamps. Feed enough cable
through these parts until the center of the Phillystran cable coil is located at the
truss bracket. Insure there is enough slack in the cable to form a loose safety
loop between the turnbuckles. Tighten the cable clamps beginning with the clamp
closest to the thimble.
Refer to Figure 4B for attachment of the cable to the boom ends. Place a thimble
(59) on the 1/4-20 x 1" bolt. Place three loose cable clamps (24) onto the cable
end. Feed the cable end through the element bracket and around the thimble. Run the cable back through the cable clamps. Tighten the cable to remove the
majority of the sag from the boom. Space the cable clamps 2 inches (5.1 cm) apart. Insure the load bearing cable is seated in the cable clamp saddle as
shown above. Tighten the cable clamps beginning with the clamp closest to the thimble. Cut off excess cable 2” (5.1 cm) after the third cable clamp.
Adjust each turnbuckle to bring each boom end level with the center. Phillystran cable has a minimal amount of stretch over time. A safety wire can be placed
through the turnbuckle openings to keep the turnbuckles from unscrewing.
22
24
59
91
207
208
209
24
24
24
24
23
207
208
209
ID Part # Description Dimensions Qty
22 094622 Phillystran 1/8” x 35’ 1
Cable (.3 x 10.7m)
24 024624 Cable 1/8” 12
Clamp (.3 cm)
23 024623 Turnbuckle 5/16”-4” 2
(.79-10.2 cm)
91 194791 Truss 2” x 42” x 1/8” 1
Bracket (5.1 x 10.2 x .3 cm)
35 170035 Aluminum 2-1/2” 1
V-Block (6.3 cm)
59 024259 Thimble 1/8” 4
(.3 cm)
207 010207 SS Flat 3/8” 2
Washer (.95 cm)
208 010208 SS Lock 3/8” 2
Washer (.95 cm)
209 010209 SS Nut 3/8” 2
(.95 cm)
3209 013209 U-Bolt 2-7/8” 1
(7.3 cm)
3209
23
Bottom of saddle
Load bearing
strand lays in
bottom of saddle.
2”
(5.1 CM)
SAFETY
LOOP
59
35