ASSEMBLY AND INST ALLATION
A270-6S
2 METER/70 CM YAGI ANTENNA
144-148/430-450 MHz
COMMUNICATIONS ANTENNAS
951453 (3/95)
A270-6S
WARNING
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 VHF/UHF antenna is designed and manufactured to give top performance and trouble free service. The antenna will perform as
specified if the instructions and suggestions are followed and care is used in assembly and installation. When checking the components received
in your antenna package use the parts lists in each section. It is easiest to identify the various dimensions of tubing by separating them into groups
of the same diameter and length. If you are unable to locate any tube or component, check the inside of all tubing.
label from the outside of the carton. Each antenna is weighed at the factory to verify the parts count. If you claim a missing part, you will be asked
for the weight verification label.
There is a master parts list on page 2.
IMPORTANT: save the weight
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. YOU MUST INSURE THAT NEITHER PEOPLE NOR PETS CAN COME IN CONTACT WITH YOUR ANTENNA
WHILE IT IS IN OPERATION. DEADLY VOLTAGES AND CURRENTS MAY EXIST. ALSO, SINCE THE EFFECTS OF EXPOSURE TO RF 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 F.
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 in charge and that they must follow your instructions. If you have any doubts at all employ a professional antenna
installation company to install your antenna.
MOUNTING
The A270-6S mast mount bracket will take up to a 2" (5.1 cm) O.D. mast. A 1-1/4" (3.17 cm) television type tubing is satisfactory for a single A2706S beam. A good heavy-duty antenna rotator will provide the best service and longest life. Often it is desirable to mount several antennas on one
mast. To keep possible interaction to minimum, place your antennas as far apart as you can. For vertical polarization (normally FM and packet),
mount the A270-6S as shown in figure G. For horizontal polarization (normally SSB and CW), mount the A270-6S with the elements parallel to
the ground.
SYSTEM GROUNDING
Direct grounding of the antenna, mast and tower is very important. This serves as protection from lightning strikes, static buildup and 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 non-corrosive 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 6. After the antenna is completely assembled, verify
dimensions and element spacings for accuracy. Then, return to the section below for final tuning.
TUNING PROCEDURE
The A270-6S does not normally require tuning after assembly. Due to the difficulty in adjusting the tuning without the proper test equipment,
we do not advise adjusting either of the Reddi-Match straps. Please use the factory specified settings. An VSWR of 2:1 or less is sufficient.
However, if you wish to check the VSWR before installation, please observe the following procedures. To prevent detuning the antenna, it should
be tuned in place or at least 7 feet (2.1 m) above ground and clear of surrounding objects. Keep all metal obstructions such as guy wires and other
antennas at least 7 feet (2.1 m) away since they will nullify any adjustment and degraded performance will result.
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 (3 m) or less] from the VSWR bridge to the
antenna. Set the transmitter to your center operating frequency. When you read VSWR, be sure you move far enough away from the antenna
so that your body does not effect the reading. Note: The feedline harness (FL) must be connected to both driven elements for proper match.
Do not attempt to match separately since the two driven elements interact.
Measure the VSWR. If it is greater than 2:1, move the tuning strap for that band by 1/8" (.3 cm) in one direction and check the VSWR. If the VSWR
improves, continue moving the tuning strap in the same direction. If the VSWR deteriorates then move the tuning strap in the opposite direction.
Repeat this procedure until no further improvement can be made. Alternate between adjusting both 2m and 70cm until an SWR of 2:1 or better
is achieved on both bands. You have matched your antenna to 50 Ohms. Note that both driven elements will have a slight interaction when adjusted
for best match. Very little improvement in performance will result from a match better than 2:1 VSWR. Tighten all connections making sure to keep
the Reddi-Match assembly parallel to the elements (EC & ED). Tape the feedlineharness to the boom and mast (figure G).
1
A270-6S
MASTER PARTS LIST
9 010009 8-32 x 5/8" (1.6 cm) stainless steel machine screw 3
11 010011 8-32 stainless steel hex nut 11
23 190023 Connector bracket, small 1
26 190026 7/8" x 1-1/2" (2.2 x 3.8 cm) mounting bracket 6
28 190028 Aluminum half washer 4
32 190032 3-5/8" x 2-1/2" (9.2 x 6.3 cm) U-bolt bracket 1
33 190033 3-1/2" (8.9 cm) U-bolt backing plate 1
41 011941 #8 stainless steel lock washer 11
43 190043 Connector bracket, large 1
53 050053 1/2" (1.3 cm) black plastic cap 4
61 050061 7/8" (2.2 cm) black plastic cap 2
115 050115 Connector boot 1
116 240116 Silicone package 2
118 010118 5/16" (.8 cm) stainless steel hex nut 2
119 010119 5/16" (.8 cm) stainless steel lock washer 2
120 010120 8-32 x 2" (5.1 cm) stainless steel machine screw 2
125 200125 tuning strap, large 1
231 010231 8-32 x 1-3/4" (4.4 cm) stainless steel machine screw 4
405 010405 5/16" x 4-1/2" x 2-7/16" (.8 x 11.4 x6.2 cm) ss U-bolt 1
326 290326 Danger label 1
921 200921 Reddi-Match clamp 4
941 360941 #8 aluminum flat washer
KEY PART # DESCRIPTION QUANTITYKEY PART # DESCRIPTION QUANTITY
BA 7/8" x 33-1/2" (2.2 x 85.1 cm) aluminum tubing 1
EA 41" (104.1 cm) element rod 1
EB 14-15/16" (37.9 cm) element rod 1
EC 1/2" x 38" (1.3 x 96.5 cm) element tube, drilled in ctr 1
ED 1/2" x 12-7/16" (1.3 x 31.6 cm) element tube, drilled in ctr 1
EE 12-1/16" (30.6 cm) element rod 1
EF 36" (91.4 cm) element rod 1
FL Feedline harness 1
RM1 5-1/2" (14 cm) Reddi-Match assembly for 2 meters 1
RM2 3-3/8" (8.6 cm) Reddi-Match assembly for 70 cm 1
#1 - BOOM ASSEMBLY
To make sure that the elements are mounted on the boom in the
proper sequence it is necessary to determine the front and back of
the boom (Figure A). The four larger holes are the U-bolt mounting
holes and are located at the back of the boom.
FIGURE A
U-BOLT
61
HOLES
BACK FRONT
15-1/8
(38.4 cm)
18-7/8"
(47.9 cm)
24-1/16"
(61.1 cm)
2M DRIVEN
ELEMENT
HOLE
20-5/8"
(52.4 cm)
31-7/8"
(81 cm)
KEY P/N DISPLAY DESC SIZE QTY
BA ALUM 7/8" x 33-1/2" 1
61 050061 PLASTIC 7/8" 2
TUBE (2.2 x 85.1 cm)
CAP (2.2 cm)
70 CM DRIVEN
ELEMENT
HOLE
61
33-1/2"
(85.1 cm)
2
Loading...