Directive Systems & Engineering DSE3-50LVA User manual

DSE3-50LVA Rev 10/20
Directive Systems & Engineering
2702 Rodgers Terrace
Haymarket, VA 20169-1628
www.directivesystems.com
703-754-3876
3-ELEMENT 50-MHZ YAGI REAR MOUNT, DSE3-50LVA
INTRODUCTION
The Directive Systems DSE3-50LVA is a rear mount 3 element Yagi-Uda antenna that
provides optimum performance for a 6-foot boom-length antenna, while addressing construction
details of importance to the first-time, as well as the experienced, builder. Design issues such as
selecting the grade of aluminum used for boom and element material to assure harsh-environment
survivability, use of stainless-steel boom hardware and element-assembly hardware, and use of
commonly available hand tools to aid in ease of construction, have been considered in producing an
antenna kit which is complete, satisfying to build, and gives the builder one of the finest 6-meter
antennas available. A vertical stack of four or eight makes a great fixed array.
ELECTRICAL SPECIFICATIONS
Calculated gain: 10.2 dBi
SWR 1.5:1 Bandwidth: 2 MHz
SWR 50.1 MHz Less than1.3:1 typical
F/B ratio: >20 dB
Impedance: 50 ohms nominal
Maximum Power: 1000 Watts
Optimal stacking distance 10 feet (1/2 wl)
MECHANICAL SPECIFICATIONS
Length: 90 inches
Turning radius: N/A
Boom-sections/elements 6063-T832 aluminum
1.375" x .058" wall
Element sections: 5/8" & ½" x .058" wall
T-match arms: 3/8" x .058" wall
All stainless steel hardware.
Surface area: ~1.5 square feet
Wind survival: 90+ mph
Maximum mast size: 2.0" OD –larger on Special orders
Coax connector: Weatherproof N–type
Assembled weight: 7.5 lbs
BEFORE INSTALLING YOUR NEW ANTENNA, PLEASE BE SURE
TO READ THE ENCLOSED WARNING PAMPHLET.

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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 TIPS AND NOTES
TOOLS
Assembly of your antenna kit requires the following tools.
12’ or greater tape measure
#2 Phillips screwdrivers
7/16” wrench or rachet and socket
Permanent marker (Sharpie)
Pliers
5/16” nut driver or flat blade screw driver
ASSEMBLY TIPS
1. Read an entire section before performing each assembly operation.
2. This Manual contains assembly drawings and other assembly-related information such as
element lengths. Drawings are referred to by Figure number; charts and lists are referred to
by Table number. Continue using the same Table or Figure number until told to use a different
one.
3. All of the information needed to successfully complete the construction of an antenna kit is
contained in this Manual. Keep this Manual in a safe place so that it will be available should
you require it for future reference.
4. When tightening hardware FOLLOW INSTRUCTIONS –DO NOT OVER TIGHTEN!
Deformation of the boom may occur, causing misalignment of elements.
5. Orient all hardware as instructed in each assembly step and as may be shown in an
associated figure.
Elements will be called out by their position on the boom, R = reflector, DE = driven element and D-
element number = director. The director’s number is relative to the DE element with D-1 nearest the
DE. The elements are marked R, DE and D.

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PARTS LIST
Note: All hardware is Stainless Steel unless otherwise noted.
Unpack the antenna kit and check each part against the following list. Do not throw any packing
material away until the antenna is completely assembled and ready for final installation. Some parts
may be packed inside boom sections.
The box in which the antenna was shipped contains the following items:
1 6’ Boom section
1 24” Front boom extension
1 Boom to mast plate
6 Element halves (R, DE, D)
3 Element couplers
2 48” T-arms
1 Connector bracket assembly
1 Balun
1 Anti Seize Compound
Hardware Bag 1
Boom-to-Mast Hardware 2
2 T-arm shorting bars
4 8-32 x 1¼” Machine screws
5 #8 Nuts
4 #8 Split lock washers
2 #8 Internal tooth lock washers
2 6-32 x ½” Machine screws
4 #6 Internal tooth lock washers
3 1 ½” U-bolts
6 ¼” Locknuts
2 ¼” x 1 ¾” U-bolts
4 ¼” Nuts
4 ¼” Lock washers
4 ¼” Flat washers
2 5/16” U-bolts
4 5/16” Nuts
4 5/16” Lock washers
4 5/16” Flat washers
3 Element saddles 1 Assembly Manual
2 3/8” T-arm End caps
6 ½” Element End caps
1 1 ¼” End cap
1 1 3/8” End cap
1 1 ½” Hose Clamp
3 Cable ties
Anti-Seize Compound - Apply a small amount to the aluminum joints to prevent the aluminum from
oxidizing and to the threads of the U-Bolts to prevent galling.
ANTENNA ASSEMBLY
1. Locate the 6’ boom section, the 24” front boom extension and the 1 ½” hose clamp. The front of
the boom is slotted and the rear has a sleeve pop riveted inside. Apply a small amount of anti-
seize to the 24” extension and slide it 6” inside the slotted end of the main boom and secure with
the hose clamp.

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2. Using a permanent marker (refer to Figure 1), place a mark 2” from the front end of the boom (the
24” extension) –this is the Director mount point. All further measurements are made from this end
of the boom. Next, place a mark at 29 ½” –this is the Driven Element point. Last, place a mark at
67 ½” – this is the Reflector.
3. Starting with the Reflector elements (R), slide the two halves into the element coupler until you
see the holes in the elements line up with the holes in the element coupler. Pass a U-bolt from the
hardware bag over the boom, through an element saddle and then through the holes in the
element. Align this assembly on the rear of the boom so that the U-bolt covers the mark you made
in step #1. Install two ¼” locknuts and tighten.
D
105"DE
112¾” R
117"
DSE3-50LVA Dimensions
All distances measured
from front of the boom
Drawing not to scale –all
dimensions +/- ¼”
2" 29 ½”
67 ½”
Figure 1
4. The Driven Element (DE) mounts the same way; however, the connector bracket sits between the
element and the element to boom saddle (see Figure 2).
5. Similarly, assemble the Director (D) and attach it at the appropriate mark on the boom, making
sure the element is perpendicular to the Reflector.

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6. Locate the two 3/8” X 48” T-arms and the balun, and from the hardware bag locate the T-arm
shorting bars, the #8 hardware and the #6 hardware. The connector bracket came with the Delrin
standoffs already installed. Using a 6-32 X ½” screw, place an internal tooth lock washer on the
screw and put the screw through one of the balun lugs connected to the center conductor. Next,
place the screw through the lug from the coax connector and then through one of the tee arms
and screw it in to the Delrin standoff insulator. Do not over tighten the screw as you can strip
the threads in the standoff insulator. Slide the T-arm shorting strap over the end of the driven
element and the T-arm. The shorting bar should be 37 1/8” from the center of the N connector.
Install 8-32 X 1 ¼” screws through the two holes in the shorting bars and install a lock washer and
nut. Finger-tighten both the shorting bar nuts.
7. Attach the other T-arm in a similar fashion, but without the wire coming from the connector, and
locate the shorting strap 37 1/8” from the center of the N connector. Connect both ground wires
from both ends of the balun to the grounding screw just below the connector. Place a lock washer
on the stud first, then both lugs, another lock washer and then the nut and finger-tighten. Refer to
Figure 3 for details.
Boom
1/4" X 1 1/2" X 3" U-BOLT
Delrin standoff insulators
connection point for
Balun and T-match arms
Front
Driven element
Element Saddle bracket
N-Connector
¼” Locknut
Figure 2
8. Securely attach the balun to the boom with the supplied cable ties as pictured in Figure 3.
Figure 3

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9. Install supplied plastic caps on ends of tubing.
10.Place the boom-to-mast plate against the boom behind the reflector and 2” from the rear end of
the boom. From the Boom-to-Mast hardware bag, use two ¼” U-bolts, ¼” flat washers, lock
washers and nuts. Tighten the four ¼” nuts, making sure the boom-to-mast plate is perpendicular
to the elements.
11.This completes the antenna assembly. Using the dimensions shown, the SWR below 50.4 MHz
will be 1.3:1 or less. If you wish to improve the match, support the antenna at least one
wavelength above the ground (about 20 feet). Check the match using a directional wattmeter or
antenna analyzer. You can move the shorting bars in or out to change the match on the antenna.
Always use coax in multiples of one half wavelength when testing to ensure you are seeing the
real match of the antenna. After completing your match adjustment, or if you don’t want to adjust,
tighten the four nuts on the shorting bars.
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.
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 resolve your problem.
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.