Allen Telecom DECIBEL PRODUCTS DB436 Quick start guide

DB436 / DB437 / DB438 Directional Antennas
406-420 MHz, 425-445 MHz, 450-470 MHz, 470-494 MHz, 488-512 MHz
Assembly and Mounting Instructions
Page 1 of 2 • July 2002 • 095028-000-M
PRODUCT DESCRIPTION
Decibel designed the DB4 6/DB4 7/DB4 8 multi-element yagi antennas
to provide high directivity and high front-to-back ratio. The DB4 6/DB4 7/
DB4 8 have a band width of approximately 0 MHz with a VSWR of less
than 1.5 to 1. They can be stacked and phased together to form the DB4 6-
2/DB4 7-2/DB4 8-2 or the DB4 6-4/DB4 7-4/DB4 8-4 for additional gain.
DB436/DB437/DB438 INSTALLATION PROCEDURE
Refer to Figure 4 while performing this procedure.
1. After removing the antenna from the shipping box, inspect it for physical
damage and to make sure all parts are on hand.
2. Inspect the antenna feed assembly output connector to determine that
it mates with the end of your station transmission line. Do not remove
any connectors or cables from the antenna feed assembly; they are
part of the antenna.
. Verify that the frequency band to which your antenna has been tuned
matches the frequency on which your radio system operates.
4. Determine the direction of the desired maximum range and the tower
leg on which the antenna is to be mounted. Mount the antenna to the
tower using the V-bolts and straps furnished, making sure that the “UP”
arrow on the feed dipole is properly positioned. Orient the antenna and
tighten the mounting clamps securely to avoid movement after align-
ment.
5. Decibel recommends that the VSWR be measured at the antenna at
this point. Note this measurement carefully and record it for future refer-
ence.
6. After checking the VSWR at the antenna, connect the station transmis-
sion line to the antenna. Make the connection snug but do not apply
heavy force with pliers. To avoid moisture problems, carefully wrap the
connection with Vapor-Wrap (part no. 11 17 or 11 16), working the com-
pound into all cracks and smoothing it over the outer jackets. Failure to
waterproof the cable will result in improper operation of the antenna.
Properly secure the feeder cable and antenna transmission line to the
tower in the best position to avoid physical damage to the cable.
7. After the antenna and transmission line installation has been completed,
make a careful check to ensure that:
• All mechanical connections have been securely made.
• The antenna is mounted on the proper leg of the tower with
sufficient physical clearance.
• The radiating element is mounted with the “UP” arrow in the
proper position.
• All connections have been carefully wrapped with Vapor-Wrap to
prevent moisture problems.
DB436-2/DB437-2/DB438-2 INSTALLATION PROCEDURE
The DB4 6-2/DB4 7-2/DB4 8-2 consist of two DB4 6/DB4 7/DB4 8 multi-
element yagi antennas with a phasing transformer for connecting the two
Figure 4 - DB436/DB437/DB438Figure 3
Mounting Clamp Detail
Figure 2
Side-by-Side Mounting Detail
DB4 7 Gold Anodized
Antenna
Horizontal
Polarization
Vertical
Polarization
To transmission line To transmission line
DB4 6 Antenna
DB4 8 Gold Anodized
Antenna
Figure 1 - DB Dire tional Antennas
GENERAL MOUNTING INFORMATION
The DB4 6/DB4 7/DB4 8 antennas come complete with heavy-duty
mounting brackets and stainless steel clamps for mounting on an angled
or round leg, either on the top or side of a tower or wooden pole. The
unique mounting arrangement of the antenna permits either vertical or
horizontal polarization as well as rapid azimuth orientation (see Figure 4).
When mounting the antenna, make sure the elements clear all guy wires
or other metal objects by at least 2 to feet. When mounting a stacked-
phased array (DB4 6-2/DB4 7-2/DB4 8-2 or DB4 6-4/DB4 7-4/DB4 8-
4), make sure the arrays are stacked collinearly and/or are exactly parallel
to each other in the case of side-by-side mounting. Side-by-side arrays
require a DB5009 mounting bracket for the DB4 6-2/DB4 7-2/DB4 8-2
and a DB5018 mounting bracket for the DB4 6-4/DB4 7-4/DB4 8-4. Continued on page 2
8635 Stemmons Freeway • P. O. Box 569610 • Dallas, Texas 75356 9610
214 / 631 0310 • Fax: 214 / 631 4706 • Web: www.decibelproducts.com

DB436 / DB437 / DB438 Directi nal Antennas Decibel Pr ducts
Page 2 of 2 • July 2002 • 095028-000-M
8635 Stemmons Freeway • P. O. Box 569610 • Dallas, Texas 75356 9610
214 / 631 0310 • Fax: 214 / 631 4706 • Web: www.decibelproducts.com
DB436-4/DB437-4/DB438-4 INSTALLATION PROCEDURE
The DB4 6-4/DB4 7-4/DB4 8-4 antennas consist of four multi-element
yagi DB4 6/DB4 7/DB4 8 antennas with a phasing harness to connect
the four units together. Refer to Figure 6 when performing this procedure.
1. Proceed with steps 1 through in the DB4 6/DB4 7/DB4 8 Installation
Procedure for each of the four yagi antennas (see page 1).
2. Mount Antenna number 1 using the V-bolts and straps furnished.
. Measure length “A” (refer to Table 1) down the tower (or the same dis-
tance from side-to-side) from the center of Antenna number 1 to deter-
mine the location for mounting the center of Antenna number 2. Mount
Antenna number 2 as in step 2 above.
4. Measure length “A” from the center of Antenna number 2 to determine
the location for Antenna number . Mount Antenna number as in step
2 above.
5. Measure length “A” from the center of Antenna number to determine
the location for mounting the center of Antenna number 4. Mount An-
tenna number 4 as in step 2 above.
6. At this point, the four individual antennas should be mounted. Connect
the four units together with the DB4 6-4/DB4 7-4/DB4 8-4 phasing
harness (see Figure 6) matching the color code.
7. Follow steps 5 through 7 in the DB4 6/DB4 7/DB4 8 Installation Pro-
cedure (see page 1) to assure proper operation of the Antenna System.
Figure 6 - DB436/DB437/DB438-4
Continued from page 1
units together. Antennas mounted collinearly with all elements directly in
line down the tower obtain the best performance. In the case of side-by-
side mounting, antennas oriented parallel to each other obtain the best
performance. Refer to Figure 5 when performing this procedure.
1. Proceed with steps 1 through of the DB4 6/DB4 7/DB4 8 Installa-
tion Procedure for both units (see page 1). Determine the direction of
the desired maximum range and the tower leg on which the antennas
will be mounted. Mount Antenna number 1 using V-bolts and straps
furnished.
2. Measure length “A” (refer to Table 1) down the tower from the center of
Antenna number 1 to determine the location for mounting the center of
Antenna number 2. Mount Antenna number 2 as in step 1 above. In
the case of side-by-side mounting, make sure that distance “A” sepa-
rates the two yagi antennas. Determine that the “UP” arrow on the feed
dipole is properly positioned.
. Connect the two units together with the transformer. Make connection
snug but do not apply heavy force with pliers. This should leave the
phasing harness transformer open for connection to the station trans-
mission line.
4. Follow steps 5 through 7 in the DB4 6/DB4 7/DB4 8 Installation Pro-
cedure (see page 1) to assure proper operation of the Antenna System.
Warning!
Installation of this product near power lines is dangerous.
For your safety, follow the installation procedures.
Table 1 - Mounting Measurements
Figure 5 - DB436/DB437/DB438-2
OUT OUT
OUT OUT
Frequency "A" Measurement
ange (MHz) Lengths (inches)
406-420 28
425-445 27
450-470 25
470-494 24
494-512 2
DB4 6-2
Phasing
Transformer