Directive Systems & Engineering DSE2425LYK User manual

DSE2425LYK Rev 4/21
Directive Systems & Engineering
2702 Rodgers Terrace
Haymarket, VA 20169-1628
www.directivesystems.com
703-754-3876
24cm Loop Yagi Kit, Model DSE2425LYK
SPECIFICATIONS
Frequency range: 1.24 to 1.27 GHz Gain: 18.5 dBi
Number of elements: 25 3 dB Beamwidth
Boom length: 72 inches (E plane): 24º
Boom diameter: 1 inch F/B ratio: >20 dB
Mast diameter: 2 inches max Maximum Power: 550 W average
Weight: (assembled) 3 pounds Stacking distance: 19 ¼” (48.9cm) V
Connector: Type-N female 21 ¾” (55.25cm) H
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.
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
2 .058" x 1" drilled boom 25 4-40 x 1 1/4” screw
1reflector 1 (1/4” wide) 25 4-40 lock nut
1reflector 2 (3/8” wide) 28-32 x 1 1/4” screw
1 driven element 2 8-32 x 2” screw
4 directors 1-4 (1/4" wide) 4 8-32 hex nut
7 directors 5-11 4 #8 Split Lock Washer
6 directors 12-17 1 Boom to Mast Bracket
5 directors 18-22 1 Boom to Mast Plate
1Anti-Seize Compound 1 2" U-bolt with nuts & lock washers
2 1" Black End Cap 1 Saddle
1Cable assembly w/connector
1 Assembly Manual

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DSE2425LYK Rev 4/21
(Can be up or down) (Can be left or right)
ASSEMBLY INSTRUCTIONS
1) Attach loops to the boom with 4-40 screws and locknuts 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. The boom is spliced between D12 and D13 and is
held together by the mounting screws for these elements. 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 1/4-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 bracket (3/4" square tubing) to the boom with 8-32 x 2"
hardware at director # 10. Note that the nut for D10 aligns with the large clearance hole in the
bracket. Attach the boom to mast plate to BM bracket with 8-32 x 1 1/4" hardware. Install U-
bolt and saddle in mast plate. The mounting mast may be up to 2" in diameter and should be
installed directly underneath the antenna boom.
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

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DSE2425LYK Rev 4/21
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
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
DSE2425LYK.
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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DSE2425LYK Rev 4/21
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. R1 and D1-D4 are
0.250-inch-wide; the rest are 0.375 inch wide. Note that the element spacing from D7 on is
3.56 inches. The feed coaxial cable (0.141-inch semi rigid) goes through the mounting bolt
and is soldered to the open ends of the element. 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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DSE2425LYK Rev 4/21
Note: All dimensions are in inches
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.