CUSHCRAFT AR-270B Instruction Manual

951374 (10/93)
C O R P O R A T I O N
AR-270B
DUAL BAND RINGO
70 CM / 2 METER
ASSEMBLY AND INSTALLATION

AR-270B
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, SUP-
PORTING 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.
YourCushcraftdualbandverticalisdesignedtogivetopperformanceandtroublefreeservice. Thisantennawillperform
asspecifiedifthesuggestionsarefollowedandcareisusedinassemblyandinstallation. Whencheckingthecomponents
received in your antenna package, use the parts lists in each section. There is also a master parts list.
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.
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.
MOUNTING
TheAR-270Bwill take up to a 2" (5.1 cm)ODmast. Forallinstallationstheantennamustbemountedonthetop6inches
(15 cm) of a mast. It should be mounted above horizontally polarized beam antennas. If you side mount this antenna on
a tower it will require a short mast, secured at two points. The mast should be kept at least 1/4 wavelength or 20 inches
(51 cm) away from the tower.
SYSTEM GROUNDING
Direct grounding of the antenna, mast and tower is very important. This serves as protection from lightning strikes and
staticbuildup, andfrom highvoltage whichis presentin theradio equipmentconnected tothe antenna. Agood electrical
connectionshouldbemadetooneormoregroundrods(orotherextensivegroundsystem)directlyatthebaseofthetower
or mast, using at least #10AWG ground wire and non-corrosive hardware. For details and safety standards, consult the
NationalElectricalCode. Youshouldalsouseacoaxiallightningarrester. Cushcraftoffersseveraldifferentmodels,such
as LAC-1, LAC-2 and the LAC-4 series.
ASSEMBLY
Assembleyourantennabyfollowingthedirectionsandillustrationsinsteps#1through#3. Aftertheantennaiscompletely
assembled, verify the dimensions for accuracy. Return to the section below for final tuning.
TUNING PROCEDURE
With the dimensions shown in figure 2, the antenna should not require any tuning. If you decide to minimize the VSWR
at your favorite operating frequency, insert a good quality 50 Ohm standing wave bridge as close to the antenna as
possible. First check the forward power and then the reverse power. Keep away from the antenna when making these
tests.
If the VSWR is higher than desired, loosen clamp #409 on the lower section and increase or decrease the length of
dimension "A" by 1/4" (.64 cm). If the VSWR increases, reverse direction. If the VSWR decreased, continue in this
direction until there is little or no reflected power at the bridge. Remember that both frequency bands will be affected by
this adjustment so some compromise may be required.
A VSWR of 1.5:1 meets commercial standards. Even if the VSWR is 2:1 this antenna will still radiate an optimum signal
and meet all specifications.

AR-270B
26 190026 ALUMINUM 2
BRACKET
77 050077 PLASTIC 3/8" 1
CAP (.95 cm)
84 010084 LOCK 1/4" 3
WASHER (.6 cm)
85 010085 HEX 1/4" 3
NUT (.6 cm)
227 010227 SELF TAPPING #8 x 1/2" 2
SCREW (.1.3 cm)
326 290326 DANGER 1
LABEL
407 030407 SS WORM 5/8" 1
CLAMP (1.6 cm)
409 030409 SS WORM 3/4" 1
CLAMP (1.9 cm)
971 082971 RADIAL 6-3/4" 3
RODS (17.1 cm)
BA BASE 1
ASSEMBLY
TA MIDDLE 1
ASSEMBLY
TB TOP 1
ASSEMBLY
#1 - ANTENNA ASSEMBLY
Install nut (85) then washer (84) onto each of the three
radial rods (971) per figure 1. Thread all three radials an
equal amount into the base assembly (BA) until they touch
each other inside the base tube. Be very careful not to
overtighten the radial rods or their
locking nuts. Overtightening may
cause damage not covered by the
warranty.
Attach aluminum brackets (26)
to the base tube with self-tapping
screws (227). Affix danger label
(326) as shown in Figure 1.
Figure 2
Slide worm clamp (409) over
the top tube of the base assem-
bly (BA). Insert the non-slotted
end of tube TA into BA. Refer-
ring to figure 2, set dimension A
to 18-1/8" (46 cm) and tighten
worm clamp. Slide worm clamp
(407) over the open end of TA
and insert the shorter aluminum
tube section of TB into TA. Set
the B dimension to 12" (30.5 cm)
and tighten clamp.
KEY P/N DISPLAY DESC SIZE QTY
Figure 1
326
85 84
971
227
26
227
26
BA
TB
407
TA
BA
77
409
A
18-1/8"
(46 cm)
B
12"
(30.5 cm)
NOTE:
Drain holes
must face
down.
Do not block
these holess

AR-270B
#2 - MASTING
Attach the AR-270B to the top of your mast which can be
1-1/4" to 2" (3.2-5.1 cm) outside diameter. Using the
large worm clamps (81) secure the antenna to the top of
the mast (figure 3). The radials should be at least 1/2 inch
(1.3 cm) above the top of the mast.
Figure 3
Figure 4
#3 - FEEDLINE
TheAR-270B is designed for usewith 50 Ohm coaxial cable
terminated with a PL-259 connector. Any length of feedline
canbeusedwithyourAR-270B. Theshortestlengthofcable
will have the least loss. A connector boot is included for use
with your new antenna. Slide the boot over the cable before
attachingyourPL-259(figure4). Spreadsiliconeontheouter
threads of the connector located on the base matching
assembly and on the PL-259 connector. DO NOT COAT
THECENTER PINOFTHE PL-259. Attachtheconnectorto
the base matching network. Apply the remaining silicone to
the outside of the connector. Slip the vinyl boot over the
connector and against the connector bracket for a weather-
tight connection. If you plan to install the antenna in a salty
or corrosive environment, you may want to consider coating
it with a clear marine varnish or equivalent, after it is as-
sembled.
115 050115 CONNECTOR 1
BOOT
116 240116 SILICONE 1
PACKAGE
81 032881 WORM 3" 2
CLAMP (7.6 cm)
KEY P/N DISPLAY DESC SIZE QTY
cushcraft
MASTER PARTS LIST
SILICONE GREASE
KEY PART# DESCRIPTION QTY
26 190026 Aluminum bracket 2
77 050077 Black plastic cap 1
81 032881 3" (7.6 cm) worm clamp 2
84 010084 1/4" (.6 cm) stainless steel lock washer 3
85 010085 1/4" (.6 cm) stainless steel hex nut 3
115 050115 Connector boot 1
116 240116 Silicone package 1
227 010227 #8 x 1/2" (1.3 cm) self tapping screw 2
326 290326 Danger label 1
407 030407 5/8" stainless steel worm clamp 1
409 030409 3/4" (1.9 cm) stainless steel worm clamp 1
971 082971 Radial rod 3
BA Base assembly 1
TA Middle assembly 1
TB Top assembly 1
81
81
1/2" (1.3 cm)
minimum between
top of mast
and radial rod.
cushcraft
TAPE
COAT
WITH
SILICONE
GREASE
DO NOT
COAT THE
CENTER
PIN OR
SOCKET!

AR-270B
SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE
P.O. BOX 4680, 48 PERIMETER ROAD, MANCHESTER, NH 03108 USA
603-627-7877 • FAX: [phone]
SPECIFICATIONS
Model AR-270B
Frequency, MHz 144-148 430-450
VSWR 1.2:1 Typical
2:1 Bandwidth in MHz >4 >15
Gain, dB 5.5 7.5
Power Rating, Watts FM 250 250
Horizontal Radiation
Pattern, Degrees 360 360
Height, ft (m) 7.7 (2.3)
Mast Size Range, in (cm) 1.25-2.0 (3.2-5.1)
Radial Length, in (cm) 6.75 (17.1)
Wind Load, ft
2
(m
2
) 0.47 (0.044)
Weight, lb (kg) 2.4 (1.1)
LIMITED WARRANTY
CushcraftCorporation, P.O.Box4680,Manchester, NewHampshire03108, warrantsto theoriginalconsumerpurchaser for
oneyearfromdateofpurchasethateachCushcraftantennaisfreeofdefectsinmaterialorworkmanship. If,inthejudgement
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, any implied warranty is limited in duration to one
year. Cushcraft Corporation shall not be liable for any incidental or consequential damages which 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,andyoumayalsohaveotherrightswhichvaryfromstatetostate. This warrantydoesnotextendtoanyproductswhich
have been subject to misuse, neglect, accident or improper installation. Any repairs or alterations outside of the Cushcraft
factory will nullify this warranty.
C O R P O R A T I O N