Directive Systems & Engineering DSE2455LYK User manual

DSE2455LYK Rev 4/21
Directive Systems & Engineering
2702 Rodgers Terrace
Haymarket, VA 20169-1628
www.directivesystems.com
703-754-3876
24cm Loop Yagi Kit, Model DSE2455LYK (w/sub-boom)
SPECIFICATIONS
Frequency range: 1.24 to 1.27 GHz Gain: ≅21 dBi
Number of elements: 55 3 dB Beamwidth
Boom length: 180 inches (E plane): ≅14º
Boom diameter: 1 inch F/B ratio: >20 dB
Mast diameter: 2 inch max Maximum Power: 550 W average
Weight: (assembled) 7 pounds Stacking distance: 26 inches’ vertical
Connector: Type-N female 29 inches’ 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.
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.
Quantity Description Quantity Description
3 .058" x 1" drilled boom 55 4-40 x 1 1/4” screw
1 74 1/4" x 3/4" square sub-boom 56 4-40 lock nut
2 sub-boom brackets 4 8-32 x 1/2” screw
2 sub-boom plates 88-32 x 1 1/4” screw
1reflector 1 (1/4”) 48-32 x 1 3/8” screw
1reflector 2 (3/8”) 28-32 x 2” screw
1 driven element 18 #8 hex nut
4 directors 1-4 (1/4" wide) 18 #8 Split Lock Washer
7 directors 5-11 1 boom to Mast Bracket
6 directors 12-17 1 boom to Mast Plate
6 directors 18-23 2 2" U-bolt with nuts & lock washers
12 directors 24-35 2 saddles
7directors 36-42 1 cable assy w/connector
10 directors 43-52 1Anti-Seize Compound
2 1" Black End Cap
1 Assembly Manual

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BEFORE INSTALLING YOUR NEW ANTENNA, PLEASE BE SURE
TO READ THE ENCLOSED WARNING PAMPHLET.
(Can be up or down) (Can be left or right)
ASSEMBLY INSTRUCTIONS
1) Slide the three boom sections together, matching the colors at each splice connection.
Temporarily secure the booms with a 4-40 x 1 ¼” screw and lock nut at each boom splice.
2) Attach loops to the boom with 4-40 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. R2
(Reflector 2 -3/8" wide) is always the first element to be installed with R1 (Reflector 1 -1/4"
wide) always next to the driven element. When tightening the nuts on the parasitic directors,
be careful not to torque them too tightly. Snug down the nuts, align the elements and use a
screwdriver for final tightening. A 1/4" nut driver is almost mandatory for this job! Attach the
brass driven element with the 5/16" nut provided. If only a single antenna is being built, it does
not matter which way the loop is oriented. If antennas are to be stacked, see "Instructions for
Stacking Loop Yagis".
Refer to photos on the next few steps for clarification.
3) Mount the boom to mast bracket (square tubing piece) to the center boom section,
using 8-32 X 2" screws, lock washers and nuts. Mount the boom to mast plate to this bracket
using 8-32 x 1 ¼” screws, lock washers and nuts. Note: There may be extra holes in the plate that
may be used for different applications.
4) There are two sub-boom brackets consisting of ½” aluminum angle and sub-boom
plates. Mount the angle brackets on the front and rear boom sections using 8-32 x 1 3/8”
screws, lock washers and nuts. Mount the sub-boom plates to these brackets using 8-32 x ½”
screws, lock washers and nuts.
5) Mount the sub-boom (3/4” thick wall aluminum square tubing) to the sub-boom brackets
and boom to mast plate using 8-32 x 1 ¼” screws, lock washers and nuts. NOTE: Do not
tighten any of this hardware until sub-boom assembly is complete (see photos at end of
manual).

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6) 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
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
7) Attach the feedline and tape it to the mast. Seal all connections with silicone RTV or
equivalent.
8) Attach the two black end caps, and this will complete the assembly of your
DSE2455LYK.

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9) 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.
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 5/16-inch dia. All elements are 0.032-inch-thick and 0.375 inch wide except R1
& D1 thru 4 which are 0.250" wide. Note that the element spacing from D7 on is 3.560 inches.
The driven element is installed in the 5/16" hole in the boom. The feed coaxial cable (0.141-
inch semi rigid) goes through the mounting bolt and is formed in a 90-degree bend so that the
connector bracket can be bolted to the boom at Director #1 using the D1 hardware. The
connector end is soldered to the open ends of the brass element. Allow a 1/4" gap at the feed
point. For best match, the driven element should be approximately 2.75 inches high; this
makes it wider than it is tall. This shape can be adjusted for best match. This antenna is based
on work done by G3JVL.
Soldered Driven Element

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Boom to Mast Bracket
Boom to Mast Plate
Sub Boom
Sub Boom
Sub Boom Plate
Sub Boom
Bracket

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ELEMENT TABLE
Note: All dimensions are in inches

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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.