ASSEMBLY AND INSTALLATION
INSTRUCTIONS
738XB
70 CM OSCAR BOOMER
432-438 MHz
COMMUNICATIONS ANTENNAS
951451 (7/94)
738XB
THIS ANTENNA IS AN ELECTRICAL CONDUCTOR. CONTACT WITH POWER LINES CAN RESULT IN DEATH, OR SERIOUS INJURY.
DO NOT INSTALL THIS ANTENNA WHERE THERE IS ANY POSSIBILITY OF CONTACT WITH OR HIGH VOLTAGE ARC-OVER FROM
POWER CABLES OR SERVICE DROPS TO BUILDINGS. THE ANTENNA, SUPPORTING MAST AND/OR TOWER MUST NOT BE CLOSE
TO ANY POWER LINES DURING INSTALLATION, REMOVAL OR IN THE EVENT PART OF THE SYSTEM SHOULD ACCIDENTALLY
FALL. FOLLOW THE GUIDELINES FOR ANTENNA INSTALLATIONS RECOMMENDED BY THE U.S. CONSUMER PRODUCT SAFETY
COMMISSION AND LISTED IN THE ENCLOSED PAMPHLET.
Your Cushcraft 738XB Boomer antenna is designed and manufactured to give trouble free service. This antenna will perform as specified if the
instructions and suggestions in this manual are followed and care is used in the assembly and installation. When checking the components received
in your antenna package use the parts listed beside each diagram. There is a master parts list on page 2. If you are unable to locate any tube or
component, check the inside of all tubing.
to verify the parts count. If you claim a missing part, you will be asked for the weight verification label.
IMPORTANT: Save the weight label from the outside of the carton. Each antenna is weighed at the factory
WARNING
PLANNING
Plan your installation carefully. If you use volunteer helpers be sure that they are qualified to assist you. Make certain that everyone involved
understands that you are the boss and that they must follow your instructions. If you have any doubts at all, employ a professional antenna
installation company to install your antenna.
LOCATION
Location of the antenna is very important. Surrounding objects such as trees, power lines, other antennas, etc. will seriously reduce efficiency. To
minimize the effects of surrounding objects, mount the antenna as high and in the clear as possible. If metal guy wires are used, they should be
broken with strain insulators. EXTREME CARE MUST BE USED FOR YOUR SAFETY. YOU MUST INSURE THAT WHILE THE 738XB IS IN
OPERATION NEITHER PEOPLE OR PETS CAN COME IN CONTACT WITH ANY PORTION OF YOUR ANTENNA. DEADLY VOLTAGES AND
CURRENTS MAY EXIST. ALSO, SINCE THE EFFECTS OF EXPOSURE TO RF FIELDS ARE NOT FULLY UNDERSTOOD, LONG TERM
EXPOSURE TO INTENSE RF FIELDS IS NOT RECOMMENDED. THERE IS A WARNING STICKER WHICH MUST BE ATTACHED TO THE
BOOM AS SHOWN IN FIGURE G.
MOUNTING
The mast mount bracket will accommodate up to 2" (5.1 cm) mast. A 1-1/2" (3.8 cm) or larger heavy wall mast should be used. A good heavy duty
antenna rotator will provide the best service and longest life.
Mount your 738XB at least 10 feet (3 meters) above the ground so that the antenna may be pointed straight up. The mast should be at a 45 degree
angle to both element planes. Typical mounting is shown in Figure F.
SYSTEM GROUNDING
Direct grounding of the antenna, mast and tower is very important. This serves as protection from lightning strikes and static buildup, and from high
voltage which is present in the radio equipment connected to the antenna. A good electrical connection should be made to one or more ground rods
(or other extensive ground system) directly at the base of the tower or mast, using at least #10AWG ground wire and noncorrosive hardware. For
details and safety standards, consult the National Electrical Code. You should also use a coaxial lightning arrester. Cushcraft offers several different
models, such as LAC-1, LAC-2 and the LAC-4 series
.
ASSEMBLY
Assemble your antenna by following the directions and illustrations in steps 1 through 5. After the antenna is completely assembled, verify
dimensions and element spacings for accuracy.
HOW TO CHECK VSWR
The 738XB does not require tuning after assembly. You may check the VSWR in order to confirm assembly was done properly. The easiest place to
check the antenna is likely to be in its final mounting configuration. Orient the antenna such that it is pointing straight up. The back of the antenna
should be at least 2 feet (0.6m) off the ground.
Run the coax cable from your transmitter to the area in which the antenna is going to be tested. The length of this cable or your feedline is not critical.
Connect a good quality VSWR bridge to the end of this cable. Connect a short length of cable [10 ft. (305 cm) or less] from the VSWR bridge to the
antenna under test. Set the transmitter to your center operating frequency and measure the VSWR while taking care not to effect the measurement
with your body. A VSWR of 2:1 or less is satisfactory and will not degrade the performance. If the VSWR is greater than 2:1, check all dimensions
and connections.
1
738XB
MASTER PARTS LIST
KEY P/N DESCRIPTION QTY
11 010011 8-32 stainless steel hex nut 36
26 190026 7/8" (2.2 cm) formed aluminum bracket 38
28 190028 Aluminum half washer 38
32 190032 3-5/8" x 2-1/2" (9.2 x 6.4 cm) U-bolt bracket 3
33 190033 Aluminum backing plate 1
38 050038 1" (2.5 cm) black plastic cap 2
41 011941 No. 8 split lock washer 36
66 013766 6-32 x 2" (5.1 cm) stainless steel machine screw 2
84 010084 1/4"-20 (.6 cm) stainless steel lock washer 2
85 010085 1/4"-20 (.6 cm) stainless steel hex nut 2
108 351108 Male phono plug 1
112 010112 6-32 stainless steel hex nut 8
113 010113 6-32 stainless steel split lock washer 8
115 050115 Vinyl Boot 1
116 240116 Silicone Package 1
118 010118 5/16" (.79 cm) stainless steel hex nut 2
119 010119 5/16" (.79 cm) stainless steel lock washer 2
120 010120 8-32 x 2" (5.1 cm) stainless steel machine screw 14
231 010231 8-32 x 1-3/4" (4.4 cm) stainless steel machine screw 22
326 290326 Danger label 1
402 013402 5/16" (.8 cm) stainless steel flat washer 2
405 010405 4-1/2" x 2-7/16" (11.4 x 6.2 cm) stainless steel U-bolt 1
411 030411 1-1/4" (3.2 cm) stainless steel worm clamp 2
BA 1" x 43" (2.5 x 109.2 cm) aluminum tube, 12 holes 1
BB 1-1/8" x 72" (2.9 x 182.9 cm) aluminum tube, 16 holes 1
BC 1" x 71" (2.5 x 180 cm) aluminum tube, 14 holes 1
BN RG-303 coax balun assembly 2
FD 3/8" x 12-3/4" (1 x 32.4 cm) folded dipole assembly 2
PS738 Polarity switch assembly aluminum box 1
KEY P/N DESCRIPTION QTY
H2 12-1/4" (31.1 cm) aluminum rod 1
H3 12-7/16" (31.6 cm) aluminum rod 1
H4, H5 12-3/16" (31 cm) aluminum rod 2
H6, H7 12" (30.5 cm) aluminum rod 2
H8 11-7/8" (30.2 cm) aluminum rod 1
H9, H10, H11 11-5/8" (29.5 cm) aluminum rod 3
H12 11-1/2" (29.2 cm) aluminum rod 1
H13 11-7/16" (29 cm) aluminum rod 1
H14 11-5/16" (28.7 cm) aluminum rod 1
H15, H16 11-1/16" (28.1 cm) aluminum rod 2
H17 10-13/16" (27.5 cm) aluminum rod 1
H18 10-9/16" (26.4 cm) aluminum rod 1
V1 13-15/16" (35.4 cm) aluminum rod 1
V2 12-1/4" (31.1 cm) aluminum rod 1
V3 12-7/16" (31.6 cm) aluminum rod 1
V4 12-13/16" (31 cm) aluminum rod 1
V5 12-1/4" (31.1 cm) aluminum rod 1
V6, V7 12" (30.5 cm) aluminum rod 2
V8 11-7/8" (30.2 cm) aluminum rod 1
V9, V10, V11 11-5/8" (29.5 cm) aluminum rod 3
V12 11-1/2" (29.2 cm) aluminum rod 1
V13 11-7/16" (29 cm) aluminum rod 1
V14 11-5/16" (28.7 cm) aluminum rod 1
V15, V16 11-1/16" (28.1 cm) aluminum rod 2
V17 10-13/16 (27.5 cm) aluminum rod 1
V18 10-9/16" (26.4 cm) aluminum rod 1
H1 13-15/16" (35.4 cm) aluminum rod 1
2
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