MFJ MFJ-1890 User manual

CAUTION: Read All Instructions Before Operating Equipment
300 Industrial Park Road
Starkville, MS 39759 USA
Tel: [phone] Fax: [phone]
COPYRIGHT 2012 MFJ Enterprises Inc. Rev 1A
C
MFJ-1890
2 Element Moxon Beam for 10 meters
INSTRUCTION MANUAL

GENERAL DESCRIPTION
WARNING
WHEN INSTALLING YOUR SYSTEM, TAKE EXTREME
CARE TO AVOID ANY ACCIDENTAL CONTACT WITH
POWER LINES OR OVERHEAD OBSTRUCTIONS.
FAILURE TO EXERCISE THIS CARE COULD RESULT
IN SERIOUS OR FATAL INJURY
2
The Moxon Rectangle is a close-spaced 2-element Yagi consisting of a driven element
and a reflector with the element tips folded toward each other to reduce turning radius.
The Moxon features a broad cardioid pattern with roughly 3.3 dBd of foward gain and
front to back ratio measuring -30 dB or more. Spanning just over 12 feet and weighing
only a few pounds, it is well suited for rooftop installations using lightweight TV hardware.
Choosing a location
For best performance on receiving and transmitting, mount the antenna in a clear location
above or away from buildings, towers, feedlines, utility wires, and other antennas. While
your own ingenuity and particular circumstances will determine the final mounting method,
we’ll pass along a few ideas for both permanent installation and portable operation.
Never mount this antenna in a location that will permit unsuspecting people to come in
contact with the antenna elements.
Never mount this antenna where a mechanical failure might allow the antenna to contact
power lines or other utility wires.
Always ground the feedline at the point where it enters a building to a good earth ground
for lightning protection.
WARNING Always mount this antenna so that it is out of reach of adults and children.
The elements can cause injury and/or severe RF burns.

3
Permanent Installation
The ideal installation is a rigid pole or roof mount that puts the antenna completely
in the clear. If the ideal installation is not possible, choose the best compromise.
TV mast, heavy-duty rigid electrical conduit, and steel water pipes are suitable
mast materials. The use of soft or thin wall mast is not recommended.
Portable Operation
The MFJ-1890 may be easily transported to temporary locations for portable,
emergency, and contest operation. Even for temporary or portable operation, do not
be casual about selecting a suitable mast. If the antenna falls, it can be damaged and
may cause serious injury. Whatever type of installation you choose, remember that
the antenna should be installed where it cannot be contacted by people or animals or
come in contact with power lines.
Antenna Assembly
Assemble the antenna on a flat level surface. Avoid assembly over grass as you may
drop some of the parts and never find them again. You may use a couple of saw horses
or other means of support to aid assembly. Loosely assemble the #1 and #11 brackets
using the 1/4-20 nuts, bolts and washers as shown in figure 1. Don't forget the square
nuts that go inside the brackets. The square nuts are different for each bracket and also
take different bolts.
Figure 1
24 14
22
25
16
24
19
This hole should be 3 inches
from the end of the boom

Secure the driven element insulator to the other end of the boom also allowing 3 inches
from the center of the bracket to the end of the boom. Install the remaining two main
elements to the insulator as shown in figure 2. Leave the bracket loose enough to align
the elements when the antenna is finished.
Figure 2
Install the 5/8 elements into the bracket while it is loose on the boom. Tighten them
enough to hold the element but allow for the bracket to rotate on the boom as you
will have to align the elements with the mast when the antenna is fully assembled.
21
25
16
15
10
1
9
14
15
4
3/8 x 9 insulator
#4 hose clamp
Assemble the end elements as shown in figure 3.
Use the #4 hose clamps to secure the tubing
together. The corner tubes have one side longer
than the other. The short end should insert into the
7/16 x 20 elements. Repeat this assembly again
to make the other side of the antenna.
Short end
Figure 3
Short end
7/16 x .028 x 26
7/16 x .028 x 26
7/16 x .028 x 18
7/16 x .028 x 26
28-1/2”
6-1/4”
20-1/2”
20

5
Install the end pieces onto the elements using the #4 hose clamps. Sliding these end
pieces in and out will be how you adjust the final length of each element. Measure the
distance from the center of the boom to the outside of the element. This distance will
be the same for all four elements. Use the antenna diagram on the next page to verify
all your measurements. Install the u-bolt on the boom. Place the 1-1/4 end caps on
each end of the boom.
Figure 4
Figure 5
Short side on Driven element
Driven element
Reflector element
Attach the feed line to the driven element as shown in figure 5. Place the 5/8 clamps
3/4 inch away from the insulator. Use the 10-24 bolts nuts and lock washers to tighten
the clamps to the tube. Place the feed line eyelets over the remaining section of the
bolt and secure with another lock washer and nut. Secure the coax to the boom with
electrical tape or other suitable fasteners.
3/4”
23
18
17

6-1/4” 20-1/2”
28-1/2
74-5/8”
55-1/4”
173273 5/8 x 53-1/4 7/16 x .028 x 26
7/16 x .028 x 18
7/16 x .028 x 26 3/8 x 9”
3”
3”
long end of corner
Figure 6
6
DIRECTION OF
RF ENERGY
DRIVEN ELEMENT
REFLECTOR ELEMENT

Final Assembly
Check the alignment of the elements and make sure all hardware is tight. Mount the antenna
in the final location.
Connect the coax balun to a high quality low loss cable such as LMR-400 or equivalent.
SWR Check
Resonance can be checked with an MFJ-256 or MFJ-269. Alternately a transceiver and
SWR meter can be used. Resonance may be changed by adjusting the length of the elements.
If the resonance point is too low, shorten the element length. If the resonance point
is too high, lengthen the element length.
Grounding Considerations
Although this antenna is designed to operate efficiently without the requirement of an earth
ground, safety grounding must still be provided to protect equipment, property and persons
from the hazards fo lightning strikes and other weather related electrical discharges. In addition,
the coaxial cable feeding the antenna should have the shield grounded to eliminate the risk of
any indoor equipment failure allowing hazardous voltages that could create a shock hazard.
Adequate protection can be accomplished by grounding the shield of the coax to a good earth
ground where it enters the building, or directly burying the cable in the earth for several feet
before it enters the building. For maximum lightning protection, the coaxial cable should be
totally disconnected from the station during threatening weather conditions.
7

8
PARTS LIST
1
2
3
4
5
6
7
8
19
20
9
10
11
12
13
14
15
16
17
18
21
22
23
24
25
173273
20-1890-1
20-1890-3
20-1890-4
20-1896-5
20-1890-6
13-1890-1
161422
165138
17-1890-1
745-3104S
461057
171329
455630
758-9199
505266
500156
554099
711-1037S
554071
551367
555362
504069
500158
562961
Tube 5/8 x 53-1/4 swaged ----------------------------------------
Tube, Boom, 1-1/4 .058 x 61-1/4” Drilled --------------------
Tube, 7/16 x .028 x 26” slotted ----------------------------------
Tube, 7/16 x .028 x 18” slotted ---------------------------------
Tube, 3/8 corner ---------------------------------------------------
Rod, Fiberglass 3/8 x 9” -------------------------------------------
Balun Assembly ------------------------------------------------------
Bracket, # 11 ---------------------------------------------------------
Bracket, # 1 ----------------------------------------------------------
Parts Pack MFJ-1890
Hose Clamp #4 ------------------------------------------------------
Insulator 1-1/4- 5/8 ------------------------------------------------
Clamp, 5/8 ------------------------------------------------------------
Caplug, 1-1/4 ABS ------------------------------------------------
U-bolt 1-3/4 ----------------------------------------------------------
Bolt, 1/4-20 x 3/4 ---------------------------------------------------
Bolt, 1/4-20 x 3/8 ---------------------------------------------------
Nut, 1/4-20 Hex -----------------------------------------------------
Washer, #10 Internal lock -----------------------------------------
Nut, 10-24 Hex ------------------------------------------------------
Nut, square 1/4-20 -------------------------------------------------
Nut, square 10-24 --------------------------------------------------
Bolt, 10-24 x 1 ------------------------------------------------------
Bolt, 10-24 x ½ -----------------------------------------------------
Washer, 1/4 Internal lock ----------------------------------------
4
1
6
2
4
2
1
2
2
16
2
2
2
1
16
2
16
4
4
2
2
2
2
16

SITESELECTION
Beforeattempting
to install
your
antenna,thinkwhere
you
can best
placeyour
antennafor safety and
performance.
To determine
a safedistancefromwires,
power
linesandtrees:
1. Measurethe heightofyourantenna.
2. Addthis
lengthto the lengthof
your
toweror mast,andthen
3. Double
thistotalfortheminimumrecommendedsafedistance.
lf
you
areunable
to maintainthissafedistance,STOP!GETPROFES-
SIONAL
HELP.Manyantennasaresupportedby
pipe
mastsattached
to the chimney,
roofor sideof the house.Generally,the higherthe
antennais abovethe
ground,
the
betterit performs. Good
practice
is
to install
your
antennaabout5 to 10 feetabove
the
rooflineand
away
from
power
linesandobstructions.RememberthatFCClimits
your
antenna
heightto 60 feet.lf possible, finda
mounting
place
directlyabove
your
set,
where
theantenna
wire
can
takea short.verticaldroo
on theoutsideof thehouseforentry
througha
wall
orwindowneartheset.Yourdealercarries
a complete
lineof installationhardware.
AVOIOTHISLOCAnOil
safe distancefrom
The
power
linesshouldbe
at leasttwicetheheight
of the antenna
and
mastcombined.
CHOOSEA PROPER
SUPPORT
AND
MOUNTING
METHOD
However
you
decideto
mountandsupport
your
antenna
always
make
surethat
safetyis
your
firstconcern. Someofthemorecommon
installation
methodsareillustratedbelow.
RO OFMOUNTI NG
Theswivelfeatureof "universal"typemounting
brackets
makesa conve
-
nient
antennamountforflator peaked roofs.Oneblamptypebracketis
usedwith3 or 4 guy wiresequallyspacedaroundthemastandanchored
totheroofor
eavesbyeyebolts.Applyroofingcompoundaroundthebase
ofthebracket.screwsandeveboltsfor moisturesealino.
TELESCOPING
MAST
Guy
wiresshouldbe equally
spacedin at leastthreedirections.
Useat
leastthree
guy
wiresforeach
10footsectionof mast.
SI DEO F HO US E
MO UNTING
Thesafe
distancefrom
power
lines
is at leasttwicethe heig ht
of antenna
andmastcombined.
Whe reroofo verha ngis notexcessive,thesi deof
the
house
provides
a convenientmounting.
Positionthebrackets
overa stud
if possible, one
abovetheother,andspacetwoor threefeetapart.For
metalsiding,first
markmountingholes,thendrill
pilot
holesthrough
the
sidingto
acceptmountingscrews.
TOWER
Towersafetyis
paramount
to a good installationandrequiresthat
you
take
location,tree
growth,
soildepthand
proximity
to buildingsintoconsider-
ation.
Towerfoundationsmust
be securelybasedon a solid
concrete/
towermounting
plate.
An alt er nativ eis to si nka 4-6f ootsectionof tower
intoa concretebasefor an extremely
ruggedmount.Proper
guying
is
essentialto a safeweather-resistantinstallationthatmusthandlesevere
windloadingandis best
accomplishedwith
preformedguygrips,
torque
CH IMNEYMOUNT ING
Thechimney
is of te nan e asyand
conve-
nient
mounting
place.
Butthe chimney
must be strong
enoughto supportthe
antenna
in highwinds. Do not use a
chimney
thathasloosebricksor mortar.
A
good
chimneymount
makesuseof a 5 or
'10
foot,
1-114"diametersteel
mast,anda
heavy
dutytwostrapclamp-type
bracket.
Installtheupper
bracket
just
belowthetop
course
of bricks,and the lower
bracket
twoorthreefeet
belowthe upperbracket.
Formaximum
strength,spacethe
brack-
ets
as farapartas
possible.
brackets
andturnbuckles.Whenworkingon
towersalwaysusea safety
beltmadeof
high
quality
web-typematerial
ROOFMOUNTEO

NOTES

FULL 12 MONTH WARRANTY
MFJ Enterprises, Inc. warrants to the original owner of this product, if manufactured by MFJ Enterprises, Inc.
and purchased from an authorized dealer or directly from MFJ Enterprises, Inc. to be free from defects in
material and workmanship for a period of 12 months from date of purchase provided the following terms of this
warranty are satisfied.
1. The purchaser must retain the dated proof-of-purchase (bill of sale, canceled check, credit card or money
order receipt, etc.) describing the product to establish the validity of the warranty claim and submit the original of
machine reproduction or such proof of purchase to MFJ Enterprises, Inc. at the time of warranty service. MFJ
Enterprises, Inc. shall have the discretion to deny warranty without dated proof-of-purchase. Any evidence of
alteration, erasure, or forgery shall be cause to void any and all warranty terms immediately.
2. MFJ Enterprises, Inc. agrees to repair or replace at MFJ's option without charge to the original owner any
defective product under warrantee provided the product is returned postage prepaid to MFJ Enterprises, Inc. with
a personal check, cashiers check, or money order for $7.00 covering postage and handling.
3. MFJ Enterprises, Inc. will supply replacement parts free of charge for any MFJ product under warranty
upon request. A dated proof of purchase and a $5.00 personal check, cashiers check, or money order must be
provided to cover postage and handling.
4. This warranty is NOT void for owners who attempt to repair defective units. Technical consultation is
available by calling [phone].
5. This warranty does not apply to kits sold by or manufactured by MFJ Enterprises, Inc.
6. Wired and tested PC board products are covered by this warranty provided only the wired and tested
PC board product is returned. Wired and tested PC boards installed in the owner's cabinet or connected to
switches, jacks, or cables, etc. sent to MFJ Enterprises, Inc. will be returned at the owner's expense unrepaired.
7. Under no circumstances is MFJ Enterprises, Inc. liable for consequential damages to person or property
by the use of any MFJ products.
8. Out-of-Warranty Service: MFJ Enterprises, Inc. will repair any out-of-warranty product provided the
unit is shipped prepaid. All repaired units will be shipped COD to the owner. Repair charges will be added to
the COD fee unless other arrangements are made.
9. This warranty is given in lieu of any other warranty expressed or implied.
10. MFJ Enterprises, Inc. reserves the right to make changes or improvements in design or manufacture
without incurring any obligation to install such changes upon any of the products previously manufactured.
11. All MFJ products to be serviced in-warranty or out-of-warranty should be addressed to MFJ
Enterprises, Inc., 300 Industrial Park Road, Starkville, Mississippi 39759, USA and must be accompanied by
a letter describing the problem in detail along with a copy of your dated proof-of-purchase.
12. This warranty gives you specific rights, and you may also have other rights which vary from state to
state.
300 Industrial Park Road
Starkville, MS 39759 USA
Tel: [phone] Fax: [phone]
COPYRIGHT 2012 MFJ Enterprises Inc.
C