CUSHCRAFT A270-6S Instruction Manual

951453 (3/95)
ASSEMBLY AND INSTALLATION
A270-6S
2 METER/70 CM YAGI ANTENNA
144-148/430-450 MHz
COMMUNICATIONS ANTENNAS

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
POWERCABLESORSERVICEDROPSTOBUILDINGS. THEANTENNA,SUPPORTINGMASTAND/ORTOWERMUSTNOTBECLOSE
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.
1
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
inyour antenna packageuse theparts listsin eachsection. It iseasiest toidentify thevarious dimensionsof tubingby separatingthem intogroups
of the same diameter and length. If you are unable to locate any tube or component, check the inside of all tubing.
IMPORTANT: save the weight
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.
LOCATION
Locationofthe antennaisvery important. Surroundingobjectssuch astrees,power lines,otherantennas, etc.willseriously reduceefficiency. 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
WHILEITISINOPERATION. DEADLY VOLTAGESAND CURRENTSMAYEXIST. ALSO,SINCETHE EFFECTSOF EXPOSURETO RFARE
NOTFULLYUNDERSTOOD,LONGTERMEXPOSURETOINTENSERFFIELDSISNOTRECOMMENDED. THEREISAWARNINGSTICKER
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
TheA270-6Smast mount bracketwill take uptoa 2"(5.1cm) O.D. mast. A1-1/4"(3.17 cm)televisiontype tubing issatisfactoryfor asingleA270-
6S 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
detailsandsafetystandards,consulttheNationalElectricalCode. Youshouldalsouseacoaxiallightningarrester. Cushcraftoffersseveraldifferent
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
TheA270-6Sdoesnotnormally requiretuningafterassembly. Dueto thedifficultyin adjustingthe tuningwithoutthe propertestequipment,
wedonotadviseadjustingeitheroftheReddi-Matchstraps. Pleaseusethefactoryspecifiedsettings. AnVSWRof2:1orlessissufficient.
However, if you wish to check the VSWR before installation, please observe the following procedures. To prevent detuning the antenna, it should
betunedin place oratleast 7feet(2.1 m) abovegroundand clear ofsurroundingobjects. Keep allmetalobstructions such asguywires and other
antennas at least 7 feet (2.1 m) away since they will nullify any adjustment and degraded performance will result.
Runthecoaxcablefromyourtransmittertotheareainwhichtheantennaisgoingtobetested. Thelengthofthiscableoryourfeedlineisnotcritical.
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
sothat yourbody doesnoteffectthereading. Note:The feedlineharness (FL)mustbe connectedto bothdriven elementsfor propermatch.
Do not attempt to match separately since the two driven elements interact.
Measurethe VSWR. Ifitisgreaterthan2:1,movethetuning strap forthat bandby1/8"(.3cm)inone directionand checktheVSWR. Ifthe 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
isachievedonbothbands. Youhavematchedyourantennato50Ohms. Notethatbothdrivenelementswillhaveaslightinteractionwhenadjusted
forbest match. Verylittle improvementinperformancewillresultfromamatchbetterthan2:1 VSWR. Tightenall connectionsmaking suretokeep
the Reddi-Match assembly parallel to the elements (EC & ED). Tape the feedlineharness to the boom and mast (figure G).
A270-6S

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
MASTER PARTS LIST
KEY PART # DESCRIPTION QUANTITYKEY PART # DESCRIPTION QUANTITY
2
#1 - BOOM ASSEMBLY
A270-6S
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. BA ALUM 7/8" x 33-1/2" 1
TUBE (2.2 x 85.1 cm)
61 050061 PLASTIC 7/8" 2
CAP (2.2 cm)
KEY P/N DISPLAY DESC SIZE QTY
FIGURE A
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
15-1/8
(38.4 cm)
2M DRIVEN
ELEMENT
HOLE
33-1/2"
(85.1 cm)
61
61
BACK FRONT
U-BOLT
HOLES
70 CM DRIVEN
ELEMENT
HOLE
18-7/8"
(47.9 cm) 20-5/8"
(52.4 cm)
24-1/16"
(61.1 cm) 31-7/8"
(81 cm)

9 010009 SS MACHINE 8-32 x 5/8" 3
SCREW (1.6 cm)
11 010011 SS 8-32 7
HEX NUT
23 190023 CONNECTOR (SHORT) 1
BRACKET
26 190026 ALUMINUM 7/8" 2
BRACKET (2.2 cm)
41 011941 SS LOCK #8 7
WASHER
43 190043 CONNECTOR (LONG) 1
BRACKET
53 050053 PLASTIC 1/2" 4
CAP (1.3 cm)
#2 - REDDI-MATCH ASSEMBLY
Assemble the driven element tubes (EC &
ED)andconnectorbrackets(23&43)tothe
boom at the positions shown in figure D
usingthe hardwareshowninfigureB. Note
thatbothconnectorspointtowardstheback
of the boom. Attach the Reddi-Match sub-
assemblies starting with element EC.
Loosely attach the tuning strap (125) to the
driven element (EC) as shown. Slide the
longer Reddi-Match sub-assembly (RM1)
throughtheReddi-Matchstrapsandsecure
totheconnector usingwasher(41) and nut
(11). Setthedistancebetweenthe connec-
tor bracket (43) and the strap (125) as
shownin figureBandtightenthehardware.
AttachtheotherReddiMatchsub-assembly
(RM2) to the other driven element (ED)
using washer (41) and nut (11). Be sure to
set the Reddi-Match strap dimension
shown in figure B. Install end caps (53) on
ends of elements EC and ED.
A270-6S
FIGURE B
120 010120 SS MACHINE 8-32 x 2" 2
SCREW (5.1 cm)
125 200125 TUNING 1
STRAP
921 200921 TUNING 2
STRAP
941 360941 ALU FLAT #8 2
WASHER
EC ALUMINUM 1/2" x 38" 1
TUBE (1.3 x 96.5 cm)
ED ALUMINUM 1/2" x 12-7/16" 1
TUBE (1.3 x 31.6 cm)
RM1 REDDI-MATCH 5-1/2" 1
(2 Meter) (14.0 cm))
RM2 REDDI-MATCH 3-3/8" 1
(70 cm) (8.6 cm)
KEY P/N DISPLAY DESC SIZE QTY KEY P/N DISPLAY DESC SIZE QTY
3
1-5/8"
(4.13 cm)
Back
53 EC
26
120
43
41
11
41
11
41
11
125
9
RM1
26
941
9
41
11
23
(SHORT)
941
41 11
11
41
9
53
53
53
120
921
(LONG)
RM2
7/8"
(2.22 cm)
ED

231 28
26
11 41
BOOM
28
231
26
41 11
2 Meter
Element 70 cm
Element
Back
Sort the elements by size using Table A. (EC and ED have already
been installed.) The cutting tolerance on these elements is ±1/16" (.16
cm). Attach each element to the boom per figure C referring to figure
D for proper location.
A270-6S
#3 - ELEMENT ASSEMBLY
FIGURE C
IMPORTANT: Placement of 70cm and 2m elements and driven
elements are on opposite sides of the boom.
4
11 010011 SS 8-32 4
HEX NUT
26 190026 ALUMINUM 7/8" 4
BRACKET (2.2 cm)
28 190028 ALUMINUM 4
HALF WASHER
41 011941 SS LOCK #8 4
WASHER
231 010231 SS MACHINE 8-32 x 1-3/4" 4
SCREW (4.4 cm)
KEY P/N DISPLAY DESC SIZE QTY
TABLE A
ELEMENTS
FIGURE
D
ELEMENT LENGTH
KEY NO. INCHES CM
EA 1 41 104.1
EB 2 14-15/16 37.9
EC 3 38 96.5
ED 4 12-7/16 31.6
EE 5 12-1/16 30.6
EF 6 36 91.4
NOTE: Placement of
70cm and 2m elements
are on opposite sides of
the boom.
EA
EB
EC
ED
EE
EF
9-3/4"
(24.8 cm)
3-3/4"
(9.5 cm)
1-3/4"
(4.5 cm)
3-7/16"
(8.7 cm)
7-13/16"
(19.8 cm)
END
VIEW
BACK
FRONT
70cm
2m

FL FEEDLINE 1
HARNESS
116 240116 SILICONE 1
PACKAGE
5
A270-6S
#5 - MAST MOUNT
#4 - FEEDLINE HARNESS
Slide back all four vinyl boots on the feedline harness (FL) to expose
the male PL-259 coaxial connectors. Unthread both connectors from
the coaxial T-connector. Apply silicone grease (116) to the outer
threads of the in-line connectors on the T-connector and re-attach
both coaxial male connectors to the T-connector. Apply silicone
grease to the outer shells of both male PL-259 connectors. Do not
coat the center pin or socket of the PL-259! Slide both vinyl boots
over the connectors until they butt against the T-connector to create
a waterproof seal. Coat the outer threads of both Reddi-Match
connectors located on dipoles EC and ED. Do not coat the center
pinorsocket ofthePL-259! Threadonbothfreeendsofthefeedline
harness (FL). Note that both lengths of cable are equal. Coat outer
shellsofconnectors withsiliconegrease (116). Slide bothvinyl boots
over the PL-259 male connectors. Make sure the boots butt against
the connector brackets. Tape the feedline harness as shown (fig. E).
KEY P/N DISPLAY DESC SIZE QTY
FIGURE E
FIGURE F
Mount the antenna to your mast using the U-bolt bracket (32) and the hardware provided per figure E. When you tighten the U-bolt make sure not
to crush the boom. Affix the warning label (326) to the boom. See "MOUNTING" on page 1 concerning orientation of mast mount, elements and
Reddi-Match.
32 190032 U-BOLT 3-5/8 x 2-1/2 1
BRACKET (9.2 x 6.3 cm)
33 190033 BACKING 3-1/2" 1
PLATE (8.9 cm)
118 010118 SS HEX 5/16" 2
NUT (.8 cm)
119 010119 SS LOCK 5/16" 2
WASHER (.8 cm)
326 290326 DANGER 1
LABEL
405 010405 SS
5/16"x 4-1/2" x 2-7/16" 1
U-BOLT (.8 x 11.4 x 6.2 cm)
KEY P/N DISPLAY DESC SIZE QTY
Back
FL
FL
Vinyl
Boot
Connector
Bracket
Tape
T-Connector
ED
EC
EB
EA
32 405
61
326
119
118
33
119
118
COAT WITH SILICONE GREASE
DO NOT coat the center pin or socket!
cushcraft
SILICONE GREASE

6
A270-6S
FIGURE G
#6 - FEEDLINE
Tape your feedline down the mast (figure G). Any
lengthoffeedlinecanbeusedwithyourA270-6S. The
shortest length cable will have the least loss. Before
installing your connector, slide boot (115) over your
feedline. Now, coat the outer threads of the T-
connector with silicone grease (116). Do not coat
centerpin. ThreadPL-259 connectorontoT-connec-
tor. Apply silicone grease over outside shell of PL-
259. Slide boot over PL-259 until it butts against the
T-connector for a waterproof seal.
SPECIFICATIONS
MODEL A270-6S
Frequency, MHz 144-148
430-450
No. Elements 3/3
Forward Gain, dBd 7.8/7.8
Front to Back Ratio, dB 20/18
SWR 1.2:1 Typical
2:1 Bandwidth MHz ≥4 / ≥20
Power Rating, Watts PEP 350 / 350
3 dB Beamwidth, Degrees
E Plane 66 / 66
H Plane 108 / 108
Boom Length, ft (m) 2.8 (.85)
Longest Element, in(cm) 41 (104.1)
Turning Radius, ft (m) 2.8 (.85)
Mast Size Range, in 1.25-2.0
(cm) (3.2-5.1)
Wind Load, ft2(m2).3 (.02)
Weight, lb (kg) 1.7 (.8)
115 050115 CONN 1
BOOT
116 240116 SILICONE 1
PACKAGE
KEY P/N DISPLAY DESC SIZE QTY
cushcraft
SILICONE GREASE
A270-6S
TAPE
TAPE FL
TAPE
115
Your PL-259
connector
FL
cushcraft
SILICONE GREASE
cushcraft
Do NOT coat
center pin
or socket!!
Your
feedline
cushcraft

48 PERIMETER ROAD, MANCHESTER, NH 03108
603-627-7877 / FAX [phone]
SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE
LIMITED WARRANTY
Cushcraft Corporation, P.O. Box 4680, Manchester, New Hampshire 03108, warrants to the original consumer purchaser for one year from date
of purchase that each Cushcraft antenna is free of defects in material or workmanship. If, in the judgement of Cushcraft, any such antenna is
defective, then Cushcraft Corporation will, at its option, repair or replace the antenna at its expense within thirty days of the date the antenna is
returned (at purchasers expense) to Cushcraft or one of its authorized representatives. This warranty is in lieu of all other expressed warranties,
anyimplied warrantyislimitedinduration tooneyear. Cushcraft Corporationshallnotbeliableforanyincidentalorconsequential damageswhich
may result from a defect. Some states do not allow limitations on how long an implied warranty lasts or exclusions or limitations of incidental or
consequential damages, so the above limitation and exclusion may not apply to you. This warranty gives you specific legal rights, and you may
also have other rights which vary from state to state. This warranty does not extend to any products which have been subject to misuse, neglect,
accident or improper installation. Any repairs or alterations outside of the Cushcraft factory will nullify this warranty.
COMMUNICATIONS ANTENNAS