MFJ-1890
2 Element Moxon Beam for 10 meters
INSTRUCTION MANUAL
CAUTION: Read All Instructions Before Operating Equipment
300 Industrial Park Road
Starkville, MS 39759 USA
Tel: 662-323-9715 Fax: 662-323-6551
COPYRIGHT 2 01 2 MFJ Enterprises Inc. R ev 1A
C
GENERAL DESCRIPTION
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.
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
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.
24
14
This hole should be 3 inches
from the end of the boom
19
24
22
25
16
Figure 1
3
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.
15
20
21
15
14
10
1
9
25
16
Figure 2
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.
28-1/2”
6-1/4”
20-1/2”
Short end
#4 hose clamp
7/16 x .028 x 26
3/8 x 9 insulator
7/16 x .028 x 18
Short end
7/16 x .028 x 26
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.
7/16 x .028 x 26
Figure 3
4
Reflector element
Short side on Driven element
Driven element
Figure 4
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.
23
18
17
3/4”
Figure 5
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.
5
28-1/2
6-1/4”
20-1/2”
7/16 x .028 x 26
7/16 x .028 x 26
3/8 x 9”
7/16 x .028 x 18
long end of corner
74-5/8”
173273 5/8 x 53-1/4
DIRECTION OF
RF ENERGY
3”
3”
55-1/4”
DRIVEN ELEMENT
REFLECTOR ELEMENT
Figure 6
6
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
19
20
1
2
3
4
5
6
7
8
173273
20-1890-1
20-1890-3
20-1890-4
20-1896-5
20-1890-6
13-1890-1
161422
165138
PARTS LIST
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 ----------------------------------------------------------
4
1
6
2
4
2
1
2
2
10
11
12
13
14
15
16
17
18
21
22
23
24
25
9
17-1890-1
745-3104S
461057
171329
455630
758-9199
505266
500156
554099
711-1037S
554071
551367
555362
504069
500158
562961
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 ----------------------------------------
16
2
2
2
1
16
2
16
4
4
2
2
2
2
16
8
SITE SELECTION
Be fore at tempting
pl ace you r
an tenna fo r safe ty an d
to in stall
yo ur
an tenna, think where
pe rformanc e.
yo u
ca n bes t
TELESC O P I N G
Gu y
wi res s hou ld be equ all y
le ast thre e
gu y
MAST
wi res for eac h
sp aced in at least th ree di rec tions .
10 foo t s ect ion of mas t.
Us e at
To d ete rmi ne
1. Measure th e hei ght of you r ante nna .
2. Add this
Do uble
3.
yo u
lf
SI ONAL
to the chi mne y,
an tenna i s a bov e th e
to
in stall
fr om
an tenna
mo unting
th e ant enna
on the ou tsi de of the ho use for entry
wa ll
or wi ndo w nea r th e set . Your deale r car rie s
a com ple te
The
power
at
least twice the height
of the antenna
mast combined.
a saf e dista nce from wir es,
le ngth t o the len gth of
th is total f or the m ini mum recom men ded sa fe distanc e.
ar e una ble
po wer
safe distancef rom
lines should be
to mai ntain th is safe dist anc e, STOP! GE T PROFE S-
HE LP. Many an ten nas ar e suppo rte d by
ro of or side of the hou se. Ge ner all y, the hig her t he
yo ur
li nes and o bstru cti ons . Re member th at FC C li mits
he ight to 60 f eet . lf
pl ace
wi re
li ne of ins talla tio n har dwa re.
gr ound,
an tenna abo ut 5 to 1 0 feet abo ve
di rectly abo ve
ca n
ta ke a s hor t. ver tic al dr oo
AVOIOTHIS LOCAnOil
and
yo ur
th e
be tter it
po ssible,
yo ur
se t,
th rough a
po wer
li nes an d tre es:
to wer or m ast, and then
pi pe
ma sts at tac hed
pe rforms.
th e
fi nd a
wh ere
pr actice
Go od
ro of li ne an d
is
aw ay
yo ur
SI D E O F H O US E
Th e s afe
di stance from
an d ma st co mbi ned .
pr ovides
ho use
po ssible,
if
me tal s idi ng, fir st
si ding to
on e
ac cept mo unting screws .
MO U NT I NG
po wer
Wh ere ro of o verha ng is no t e xcess ive , the si de o f
a con ven ien t m oun tin g.
ab ove th e other, and s pace t wo o r three f eet ap art . For
ma rk mount ing h ole s, t hen dr ill
TOWER
Towe r saf ety is
lo cation, t ree
at ion.
to wer mou nti ng
in to a
es sential to a
wi nd l oad ing a nd is bes t
br ackets
towers always use a safety
qu ality
hi gh
pa ramount
gr owth,
Towe r fou nda tio ns mu st
co ncrete base for a n e xtr eme ly
an d t urn buc kle s. Wh en wo rki ng on
we b-type m ate ria l
so il depth and
pl ate.
An alt ernat ive is t o sink a 4- 6 foo t s ect ion of tow er
sa fe w eat her -resista nt in stallati on th at mus t handl e sev ere
ac complish ed wit h
li nes
is a t lea st twic e the hei ght
Po sition th e b rac kets
go od
to a
in stallati on and req uir es t hat
pr oximity
be secur ely based on a so lid
belt made of
to bu ildin gs into c ons ide r-
ru gged mou nt. Pr ope r
pr eformed g uy gr ips ,
pi lot
ho les thr oug h
of ant enna
th e
ov er a stu d
th e
yo u
ta ke
co ncrete/
gu ying
to rque
is
CHOOSE A P ROP ER
MOUNTIN G
However
sure that
installati on
you
safety is
METHOD
decide to
methods are illustrated below.
mount and support
your
SUPPORT
first c onc ern . Some of the more commo n
ROOF MOUNTEO
your
AND
antenna
RO O F MO U NT I NG
Th e s wiv el f eat ure of "u niv ers al" typ e m oun tin g
ni ent
an tenna mou nt for fla t or
us ed with 3 or 4
to the roo f or
of the b rac ket . scre ws and eve bol ts f or m ois tur e sea lin o.
gu y
wi res e qua lly spa ced a rou nd the ma st and anc hor ed
ea ves by ey ebo lts . Ap ply roo fin g c omp oun d arou nd the bas e
pe aked
br ackets
ro ofs. One bla mp ty pe br ack et is
always
make
ma kes a conve
CH I MN E Y M O UN T IN G
Th e ch imn ey
ni ent
mu st be stron g
an tenna
ch imney
go od
'1 0
fo ot,
-
he avy
In stall the up per
co urse
two or three feet
Fo r m axi mum
et s
as far apart as
is o fte n a n eas y and
mo unting
ch imney mount
du ty t wo st rap cla mp- typ e
pl ace.
Bu t t he
no t use a
ma st, and a
ju st
be low t he t op
ch imney
en ough to s upp ort t he
in high winds. Do
th at has lo ose bri cks o r m ort ar.
ma kes use of a 5 or
1- 114 " dia met er st eel
br acket
of bricks, and t he lower
below the upper bracket.
st rength, spac e th e
po ssible.
co nve-
A
br acket.
br acket
br ack-
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 (601) 323-5869.
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: 662-323-9715 Fax: 662-323-6551
COPYR IG HT 201 2 MFJ Enterp ri se s I nc .
C
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