Directive Systems & Engineering DSE3318LYRMK User manual

DSE3318LYRMK Rev 3/21
Directive Systems & Engineering
2702 Rodgers Terrace
Haymarket, VA 20169-1628
www.directivesystems.com
703-754-3876
33cm Loop Yagi (Rear Mount), Model DSE3318LYRMK
SPECIFICATIONS
Frequency Range: 890-910 MHz
Number of elements: 18
Boom Length: 72 inches
Boom diameter: 1 inch
Mast diameter: 2 inches’ max
Weight: 3 lbs assembled
Connector: Type N female
Gain: 16.5 dBi
3 dB Beamwidth (E Plane): 30°
F/B ratio: >20 dB
Maximum Power: 550 W. average
Stacking Distance:
H Plane 21 1/2 in. vertical
E Plane 24 in. horizontal
PARTS LIST
Note: All hardware is Stainless Steel unless otherwise noted.
Anti-Seize Compound - Apply a small amount of the supplied Anti-Seize Compound to the aluminum joints and
to the threads of the U-Bolts to prevent galling.
BEFORE INSTALLING YOUR NEW ANTENNA, PLEASE BE SURE
TO READ THE ENCLOSED WARNING PAMPHLET.
Quantity Description Quantity Description
2 .058" x 1" Drilled boom 18 4-40 x 1 1/4” Screw
1Boom to Mast "L" Bracket 18 4-40 Lock nut
2 Reflectors 1 & 2 28-32 x 1 3/8” Screw
1 Driven element 2 #8 Hex nut
10 Directors 1-10 2 #8 Split lock washer
5 Directors 11-15 1 Anti-Seize Compound
1 2" U-bolt with nuts & lock washers 2 1" Black End Cap
1 Saddle 1 Assembly Manual
1Cable assembly w/connector

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CAUTION: While we strive to remove all burrs from all machined parts, there is always the possibility of
sharp edges. We strongly suggest checking the edges and use a fine file, or 400 grit
sandpaper, to remove any burrs that may have been left.
ASSEMBLY INSTRUCTIONS
1) Attach loops to the boom with 4-40 x 1 ¼” screws and lock nuts in proper sequence.
Loops go on the side of the boom marked with an "X". Attach the contents of each bag of
elements before opening the next bag. This will prevent any mix-up of elements on the boom.
When tightening the nuts on the parasitic elements, be careful not to torque them too tightly.
Snug down the nuts, align the elements and use a screwdriver for the final tightening. A ¼
inch nut driver is almost mandatory for this job! Attach the driven element with the 5/16”nut
provided. If only a single antenna is being built, it doesn't matter which way the loop is
oriented. If antennas are to be stacked, see "Instructions for Stacking Loop Yagis".
2) Attach the boom to mast angle bracket (angle piece) behind the second reflector R2.
The bracket can be installed for either horizontal or vertical polarization. Install U-bolt and
saddle on the bracket.
3) Install the cable assembly through the hole in the driven element mounting bolt. Make
sure the connector bracket is correctly oriented, the bend should be forward for center mount
antennas and rear facing for rear mount antennas. Solder the outer shield to the driven loop
first making sure there is no shield sticking above the large hole in the driven loop. After the
shield is soldered, pass the center conductor through the small hole in the driven loop and
bend the center conductor over and solder (See Assembly Tips below).
We have created a You Tube video, the link of which can be found on our website,
documenting the following steps:
https://youtu.be/ojXbsDv5cvU
At this point the connector assembly is facing down, connect a piece of coax and your
SWR bridge or VNA. Pull down on the connector (which will flatten the loop) until you reach
the lowest SWR. If it’s less than 1.5:1 you can stop and make sure the loop doesn’t try to pop

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back up, sometimes you have to squeeze the loop with your fingers to make sure it stays in
the shape that gave the best SWR. If you want to further lower the SWR, from the rear of the
antenna, place both your thumbs on the driven loop on either side and gently push it forward
towards D1, you only need to tilt it maybe 3/16” to ¼” and that should drop the SWR to 1.1:1
or less.
Now, GENTLY bend the UT-141 coax after it exits the boom towards the front or rear,
depending on the mounting. You do not want to bend it so tightly that it crushes where it
extends through the bolt. The connector bracket should line up with either D1 or D2 (or the
hole with the circle around it on rear mount antennas), remove that nut and place the
connector bracket on the screw and re-attach the nut. If the bracket doesn’t line up,
sometimes you have to flip the bracket. Loosen the ¾” nut by holding the connector body with
a 9/16” open end wrench. Remove the connector bracket and flip it.
Connector doesn’t fit Front Mount Connector Rear Mount Connector
4) Attach the feedline and tape it to the mast. Seal all connections with silicone RTV or
equivalent.
5) Attach the two black end caps and this will complete the assembly of your
DSE3318LYRMK.
6) The SWR should be 1.5:1 or better. Additional tweaking can be accomplished by
adjusting the distance between the driven element and R1, or by adjusting the shape of the
driven element.
DO NOT, UNDER ANY CIRCUMSTANCES, APPLY ANY TYPE OF SEALANT OR COATING TO THE
DRIVEN ELEMENT, T-ARMS OR CONNECTOR ASSEMBLY, OTHER THAN KRYLON®
CLEAR COAT. ANY OTHER COATING WILL ADVERSELY AFFECT THE SWR AND VOID YOUR
WARRANTY.

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ASSEMBLY TIPS:
The boom diameter is 1 inch, and it is drilled for 4-40 hardware (no. 33 drill bit). The driven
element hole is enlarged to 5/16 inch. All elements are 0.032-inch-thick and 0.375 inch wide.
Note that the element spacing from D7 on is 5.115 inches. The loops and driven element are
preformed to their proper shape. The connector/coax assembly is soldered to the driven element
as shown below. Form the coax cable using your thumb as a guide to bend the coax and bracket
so that the bracket mounting hole is aligned at the R1 drilled hole in the boom. (See drawing
below.) Be careful with the .141" coax. It can be crimped if not supported by your thumb! Attach
the coax bracket with the hardware from R1. For the best match, the driven element should be
approximately 4 inches high: this makes it wider than it is tall. This shape can be adjusted for best
match. The space between the loop ends should be 3/8" (9.5mm). This spacing will prevent water
from "beading up" there during wet weather. The design of this antenna is based on work done
by G3JVL.
Soldered Driven Element
Directive Systems Warranty Policy
All Directive Systems antennas are built with the finest materials available. We take great pride
in building a quality product that will give years of good service and performance. If there is a defect
in materials or workmanship within 90 days of purchase, Directive Systems will repair or replace
the defective part, free of charge, to the original purchaser. DO NOT RETURN ANYTHING
WITHOUT PRIOR AUTHORIZATION FROM DIRECTIVE SYSTEMS. Please contact us either by
phone or email describing the problem and we will work to resolve it.
If, after examining a new antenna you received, you are not satisfied, contact us immediately
for return authorization and refund. ANY ANTENNA THAT HAS BEEN MODIFIED WILL BE
SUBJECT TO A RESTOCKING CHARGE. IF AN ANTENNA IS SO MODIFIED AS TO MAKE IT
UNUSABLE, DIRECTIVE SYSTEMS RESERVES THE RIGHT TO REFUSE TO ACCEPT THE
ANTENNA FOR RETURN.

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DSE3318LYRMK Rev 3/21
Note: All dimensions are in inches.