HyGain DX-88 user manual

8-Band HF Vertical
80 thru 10 Meters
Model DX-88
Instruction Manual
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TABLE OF CONTENTS
Chapter 1..........................................................................................................................................1-1
General Description .………...........….............................................................…............................1-1
Electrical Design..............................................................................................................................1-1
Mechanical Design….........…...........................................................................................................1-1
Specifications .....................….........................................................................................................1-2
Typical VSWR Curves..........….......................................................................................................1-2
Chapter 2.........................................................................................................................................2-1
Preparation for Assembly ...............................................................................................................2-1
Tools..................................…................................................................................................2-1
Chapter 3.....................................................................................................................................3-1
Base Assembly...........................................................................................................................3-1
80/40 Meter Assembly..............................................................................................................3-1
Capacitor Assembly..........................................................................................................................3-1
Attaching Capacitors to Coil Assembly.........................................................................................3-1
10/12/15 Meter Trap Assembly ..................................................................................................3-3
Capacitor Assembly ......................................................................................................................3-3
Attaching Capacitor to Coil Assembly..............................................................................................3-4
17/20 Meter Assembly ....................................................................................................................3-5
Capacitor Assembly ......................................................................................................................3-5
Attaching Capacitors to Coil Assembly.........................................................................................3-6
30 Meter Trap Assembly ..................................................................................................................3-7
Attaching Capacitors to Coil Assembly.................................................................................. .....3-7
Attaching Upper Radiator Tubes to 30 Meter Trap Assembly.......................................................3-8
Installation of Tubing Clamp.........................................................................................................3-9
Attaching the Trap Assemblies.................................................................................................. 3-10
DC Shorting Coil.......................................................................................................................... 3-10
Tuning the DX-88 Vertical Antenna.......................................................................................... 3-12
Chapter 4......................................................................................................................................4-1
Mounting the Antenna ......................................…………............................................................4-1
Operation ...................................................................................................................................4-4
Service Information .....................................................................................................................4-4
VSWR Record.....................................…......................................................................................4-5
Converting American Measurements to Metric......................................…...................................4-6
Chapter 5....................................................…...............................................................................5-1
Parts List......................................................................................................................................5-1
LIST OF ILLUSTRATIONS
Figure
1
2
Detail A
Detail B
Detail C
3
Detail A
Detail B
4
Detail A
Detail B
5
Detail A
Detail A
6
Detail B
Detail C
7
Detail A
Detail B
8
9
10
11
12
13
14
15
Base Assembly
80/40 Meter Assembly
45” Capacitor Assembly
1 1/8” x 1” Mast/Capacitor Clamp
1 1/8” x 7/16” Mast/Capacitor Clamp
10/12/15 Meter Capacitor Assemblies
13” Capacitor Assembly
16” Capacitor Assembly
10/12/15 Meter Trap Assembly
1 1/8” x 1” Mast/Capacitor Clamp
1 1/8” x 7/16” Mast/Capacitor Clamp
17/20 Meter Capacitor Assemblies
13” Capacitor Assembly
16” Capacitor Assembly
17/20 Meter Trap Assembly
1 1/8” x 1” Mast/Capacitor Clamp
1 1/8” x 7/16” Mast/Capacitor Clamp
30 Meter Trap Assembly
1” Mast/Capacitor Clamp
3/8” x 1” x 3/8” Mast/Capacitor Clamp
Upper Radiator Tubes Attached to 30 Meter Trap Assembly
Tubing Clamps
DC Shorting Coil
Connecting Trap Assemblies
DX-88 Overall View
DX-88 Ground Mount Radial System
DX-88 Resonant Radial System
Roof Mounted Radial System
Page
3-1
3-2
3-2
3-2
3-2
3-3
3-3
3-3
3-4
3-4
3-4
3-5
3-5
3-5
3-6
3-6
3-6
3-7
3-7
3-7
3-8
3-9
3-10
3-11
3-16
4-1
4-2
4-3
LIST OF GRAPHS AND TABLES
Graph
1
2
3
4
5
6
7
8
Table
1
2
3
Dimension A and B, 80/40 Meter for 6.9-7.3 MHz
Dimension A and B, 80/40 Meter for 3.5-4.0 MHz
Dimension C, 10 Meter Trap for 27-29.7 MHz
Dimension D, 12 Meter Trap for 24.5-26.5 MHz
Dimension E, 15 Meter Trap for 20.5-22 MHz
Dimension F, 17 Meter Trap for 17.5-18.5 MHz
Dimension G, 20 Meter Trap for 13.5-15.5 MHz
Dimension H, 30 Meter Trap for 9.5-10.5 MHz
Page
3-13
3-13
3-13
3-13
3-14
3-14
3-14
3-14
Pag
Dimension H and I for HAM and SWL Settings.....................…...........................3-15
Broadcasting Frequencies.......................................................................................3-15
Resonant Radial Lengths ........................................................................................4-3
CHAPTER I
GENERAL DESCRIPTION
ELECTRICAL DESIGN
The Hy-Gain DX-88 is an omnidirectional, unity
gain, self supporting vertical antenna that
operates in the Amateur 10, 12, 15, 17, 20, 30,
40, and 80 meter bands. This vertical antenna
may also be tuned to provide outstanding
reception in the SWL 11, 13, 16, 19, 22, 25, 31,
41, 49, 74, and 90 meter bands. The DX-88 will
work against an earth ground and a set of ground
radials or a resonant radial system when
mounted above ground. You may construct your
own radial system from information in this
manual, or you may purchase the optional
ground radial kit for the DX-88, Model GRK-88,
Order No. 189S, or the resonant roof radial kit,
Model RRK-88, Order No. 1905.
The Omni DX-88 vertical antenna utilizes its
entire length for radiation on both 80 and 40
meters.
It resonates on each of these two bands with the
aid of a tuned circuit near the base which looks
inductive in the 3.5 - 4.0 MHz band and
capacitive in the 7.0 - 7.3 MHz band. Adjustable
piston capacitors set the resonance of this tuned
circuit, which affects the amount of inductance
and capacitance, and the resulting antenna
resonances within each band.
The remaining bands are obtained by using lowloss, high-Q tunable traps to isolate one-quarter
wavelength sections along the radiator. Onequarter wavelength sections always produce lowangle radiation patterns without high-angle
lobes. The distances between the traps are fixed
and the traps themselves are tuneable, except for
the 30 meter band. This allows the antenna to
operate on the new WARC bands of 12 and 17
meters as well as the older 10, 15, and 20 meter
bands. This also allows the DX-88 to resonate on
or very close to the international SWL bands,
with the proper adjustment of each trap.
An optional 160 meter kit, Model 160 MK-88,
Order No. 191S, is also available for the DX-88
vertical. The 160 meter kit is only recommended
for ground-mounted installations.
Dimensions are included in this manual for optimization on either the CW or phone portions of
the 80, 40, and 20 meter bands. Regardless of
the optimization, the VSWR bandwidths of the
DX-88 are broad enough for the antenna to
operate at a VSWR of 2:1 or less on the 10, 12,
15, 17, and 30 meter bands. The bandwidth on
80 meters is approximately 50 KHz at 2:1
VSWR, because it is inductively loaded on this
band. The bandwidth on 40 meters is
approximately 200 KHz, and on 20 meters
approximately 250 KHz.
The Omni DX-88 vertical antenna features stainless steel hardware for all electrical and most
mechanical connections. The DX-88 also
features heavy-wall 1 3/8 inch and l 1/8 inch
aluminum tubing for high strength and large
diameter #12 copper wire coils for low loss and
high-Q performance.
A high-efficiency non-automatic band-switching
kit is available to add 160 meter operation to the
DX-88, Model 160 MK-88, Order No. 00191S.
MECHANICAL DESIGN
The DX-88 mechanical design features 0.120
wall, 1 3/8 inch and 1 1/8 inch 6063T832
aluminum tubing for extra high strength. Wind
survivability is 75 MPH WITHOUT guying. The
large diameter coils used in the traps and 80/40
tuning circuit are constructed on large diameter
high strength forms and are protected from
environment by covers made from the same
material. The DX-88 may be disassembled into
sections of less than 55 inches for easy
transportation to DX locations. All stainless
steel hose clamps and hardware are used for all
electrical connections. All insulators and coil
covers are UV protected. The coil covers may be
removed easily for cleaning, modifying or
repairing the coils. When the 160 meter kit has
been added, the wind survivability is 50 MPH
(80 kmph).
SPEC IFIC ATIONS
Elect rical
Frequency:
Transmit .............................……….................... 80, 40, 30, 20, 17, 15, 12, 10 meter A m a t e u r Bands
Receive...............................……………..................... 3-30 MHz, tunable in 8 International SWL Bands.
Input impedance .
...................…………………………………………………………………….50 ohms
VSWR at resonance..................................………………l e s s than 1.5:1 if using recommended' radial' system
Maximum Power* ...... ................... ... ..... 1500 watts PEP, 700 watts average
Input Connector ................... . .... . .. .. ............. 'SO-239 *
Maximum power on 30 meters is 250 watts a v e r a g e
*Maximum power on 17 meters is 500 watts average
Mechanical
Maximum height... ……………………………………………………………………… ....24' 9" (7.54 m)
Weight, net ........................................................……………………………………... 18 lb. (8:2 kg)
Weight, shipping ................... ........ ......... ......... .....::.......... _:....... ....................22 lb. (10.0 kg)
Recommended Mast O.D. (Mast not supplied)...............................
1 1/2" - l 5/8" (38 - 41 mm)
Wind Survival, unguyed.......................................................................... ......75 MPH (121 kmph)
Wind Survival, unguyed with 160 MK-88................................. ................... 50 MPH (80 kmph)
NOTE: If the terminals of the input connector
are checked with an ohmmeter, they will show
an open. THIS IS NORMAL! A DC shorting
coil may be constructed from information in
this manual. This coil will also improve the
impedance match on the 80 meter band.
CAUTION: When using RTTY or AM, DO
NOT transmit continuously at maximum power
for more than 5 minutes at a time, with 5
minutes off between transmissions. Do not
exceed average power limits specified for each
band.
CAUTION: Do Not use a support mast smaller
than 1 1/2" O.D. (38 mm). Small masts will not
support this antenna.
TYPICAL VSWR CURVES:
TYPICAL VSWR CURVES Cont.
CHAPTER 2
PREPARATION FOR ASSEMBLY
FOR OVERSEAS CUSTOMERS: If you use
the Metric System, see the American-ToMetric conversion table in the rear of the
manual. The illustrations in this manual will
provide both American and Metric
Dimensions.
Choose a table-top or similarly sized clear area
to assemble the Omni DX-88 vertical antenna.
A bench-vise may be used to hold the tubing
during assembly. If you assemble this antenna
over a grassy area, precautions should be taken
so that hardware is not accidentally lost during
assembly.
Tools: The following tools are required
for easy assembly of the Omni DX-88
antenna:
Tool T y p e
Qty
Tape measure, 12 ft............................ 1
Nut driver, 3/8 inch .......................... 1
Nut driver, 5/16 inch ......................... 1
Open-end wrench, 1/2 inch................ 1
Open-end wrench, 7/16 inch.............. 1
Standard wrenches or adjustable wrenches
may be used in place of the nut drivers.
When unpacking your antenna, check inside of
all tubing for small parts and elements. To
conserve space, these smaller articles are
sometimes put inside larger pieces. Check all
parts against the parts list in the rear of this
manual to ensure no parts are missing. There
should be 4 coil assemblies. These may be
identified by comparing them to Figures 2, 4,
6, and 7.
Make all measurements to the given dimensions, plus or minus not more than 1/8 inch.
The assembly of the DX-88 will be easier if
you read this manual completely through at
least twice and follow the recommended
directions. Allow at least 3 hours for
assembly.
You may wish to assemble the DX-88 in
sections in a covered area (basement, garage
or workshop etc.) out of the weather and then
brought outside for final assembly and
installation. The Major sections are:
Base Assembly
80/40 Assembly
10/12/15
Assembly 17/20
Assembly
30 Assembly with Item 11
Top Assembly - Items 2 and 10
CHAPTER 8
BASE ASSEMBLY
Select the DX-88 base assembly and assemble
as shown in Figure 1.
80/40 METER ASSEMBLY
Capacitor Assembly
Construct the two 45" capacitors for the 80/40
meter assembly. Select a 1" x 45" tube (Item
3), 7/16" x 48" tube (Item 1), 3 spacers (Item
35), 1 rain cap (Item 36), and 1 caplug (Item
34) for each capacitor assembly. Refer to
Figure 2.
Push the spacers onto the 7/16" tube and adjust
so that the top spacer is approximately 20
inches from the top end of the tube, the bottom
spacer is near the bottom end of the tube and
the remaining spacer is half-way between the
other two. Push the rain cap onto the top of this
tube and then slide this assembly into the 1" x
45" tube. Seat the rain cap over the 1 inch tube.
Repeat this instruction for the other capacitor.
DO NOT place the caplug on the 7/16" tube at
this time.
Attaching Capacitors to Coil
Loosely assemble two pairs of 11/8" x 1"
clamps and two pairs of 1 1/8" x 7/16" clamps
as shown in Details B and C of Figure 2.
Select the 80/40 meter coil assembly (Item 14)
and attach the capacitors to the coil assembly
using the clamps as shown in Figure 2. Dimensions A and B will be set later on in the
instructions.
NOTE: All clamps should be placed flush with
the coil form edge and touching each other.
The rain caps should be pushed completely on
each 1" tube, and should be flush with the
11/8" x 7/16" clamp. Tighten the hardware on
these four pairs of clamps. Place the caplug on
the top end of each 7/16" tube.
Figure 1
Base Assembly
Detail B
11/8" x 7/16" Mast/Capacitor Clamp
Detail C
1 1/8" x 1" Mast/Capacitor Clamp
Detail A
Ite
No.
1
3
14
17
18
26
Description
Tube, 7/16" x 48"
Tube, 1" x 45"
Coil Assembly, 80/40 Meters
Clamp, Mast/Capacitor, 11/8" x 1"
Clamp, Mast/Capacitor, 1 1/8" x 7/16"
Bolt, #10-24 x 1/2", hex head, stainless steel
Item
No.
28
33
34
35
36
Description
Nut, 10-24, hex, stainless steel
Lockwasher, #10, internal, stainless steel
Caplug, 7/16" Black
Insulator, 7/16" x 7/8" spacer
Rain Cap, 1"
Figure 2
80/40 Meter Assembly
10/12/15 METER TRAP
Capacitor
There is one 16 inch capacitor and two 13 inch
capacitors used in the 10, 12, and 15 meter
trap assembly.
Select one 1" x 16" tube (Item 4), 7/16" x 19"
tube (Item 8), 3 spacers (Item 35), 1 rain ap
(Item 36), and 1 caplug (Item 34).
Push the spacers onto the 7/16" x 19" tube and
adjust so that the top spacer is approximately
10 inches from the top end of the tube, and the
bottom spacer is near the bottom end of the
tube.
Detail A
13" Capacitor Assembly
The 3rd spacer should be centered between the
other two. Push the rain cap onto the top of
this tube and then slide this assembly into the
1" x 16" tube. Seat the rain cap over the 1 inch
tube.
DO NOT place the caplug on the 7/16" tube at
this time.
Select a 1" x 13" tube (Item 5), 7/16" x 16"
inch tube (Item 9), 3 spacers (Item 35), 1 rain
cap (Item 36) and 1 caplug (Item 34) for each
assembly. Assemble the 13 inch capacitors in
the same manner as the 16 inch capacitors.
DO NOT place the caplug on the 7/16" tube at
this time.
Detail B
16" Capacitor Assembly
Figure 3
10/12/15 Meter Capacitor Assemblies
Attaching Capacitors to Coil Assembly
Loosely assemble three pairs of 11/8" x 1"
clamps and three pairs of 11/8" x 7/16" clamps
as shown in Details A and B of Figure 4.
Select the 10/12/15 meter coil assembly (Item
13) and attach the capacitors onto the coil assembly using the clamps as shown in Figure 4.
Dimensions C, D, and E will be set later on in
the instructions.
NOTE: The edge of each 11/8" x 1" clamp
should be flush with the edge of each coil
form. The rain caps should be pushed
completely on each 1" tube, and should be
flush with the 11/8" x 7/16" clamp. Tighten the
hardware on these 6 pairs of clamps. Push a
caplug (Item 34) on the top end of each 7/16"
tube.
NOTE: Disassembly of clamps may be needed
to properly install them onto several inside
locations on the 10/12/15 meter trap assembly.
Detail A
1 1/8" x 1" Mast/Capacitor Clamp
Detail B
1 1/8" x 7/16" Mast/Capacitor Clamp
Figure 4
10/12/15 Meter Trap Assembly
17/20 METER ASSEMBLY
Capacitor Assembly
There is one 16 inch capacitor and one 13 inch
capacitor used in the 17/20 meter trap assembly.
Select one 1" x 16" tube (Item 4), 7/16" x 19"
tube (Item 8), 3 spacers (Item 35), 1 rain cap
(Item 36), and 1 caplug (Item 34).
Push the spacers onto the 7/16" x 19" tube and
adjust so that the top spacer is approximately
10 inches from the top end of the tube, and the
bottom spacer is near the bottom end of the
tube.
Detail A
13" Capacitor Assembly
The 3rd spacer should be centered between the
other two. Push the rain cap onto the top of
this tube and then slide this assembly into the
1" x 16" tube. Seat the rain cap over the 1 inch
tube.
DO NOT place the caplug on the 7/16" tube at
this time.
Select a 1" x 13" tube (Item 5), 7/16" x 16"
inch tube (Item 9), 3 spacers (Item 35), 1 rain
cap (Item 36) and 1 caplug (Item 34).
Assemble the 13 inch capacitor in the same
manner as the 16 inch capacitor.
DO NOT place the caplug on the 7/16" tube at
this time_
Detail B
16" Capacitor Assembly
Figure 5
17/20 Meter Capacitor Assemblies
Attaching Capacitors to Coil Assembly
Loosely assemble two pairs of 1 1/8" x 1"
clamps and two pairs of 1 1/8" x 7/16" clamps
as shown in Details A and B of Figure 6.
Select the 17/20 meter coil assembly (Item 12)
and attach the capacitors onto the coil
assembly using the clamps as shown in Figure
6. Dimensions G, and F will be set later on in
the instructions.
NOTE: The edge of each 11/8" x 1" clamp
should be flush with the bottom edge of each
coil form. The rain caps should be pushed
completely on each 1" tube, and should be
flush with the 11/8" x 7/16" clamp. Tighten the
hardware on these 4 pairs of clamps. Push the
ca
Place a large # 16 tubing clamp (Item 23) over
the slotted end (top) of this assembly, but, DO
NOT tighten at this time.
Detail A
11/8" x 7/16" Mast/Capacitor Clamp
26
Detail B
1 1/8"x 1" Mast/Capacitor Clamp
Figure 6
17/20 Meter Trap Assembly
30 METER TRAP ASSEMBLY
Attaching Capacitors to Coil
Loosely assemble a pair of 1" clamps and a
pair of 3/8" x 1" x 3/8" clamps as shown in
Details A and B of Figure 7.
Select the 30 meter coil assembly (Item 15)
and attach the capacitors onto the coil
assembly using the clamps as shown in Figure
7.
NOTE: The edge of each clamp assembly
should be flush with each edge of the coil
form. Tighten the hardware on these two
clamp assemblies.
Place a #10 tubing clamp (Item 22) over the
slotted end (top) of this assembly, but, DO
NOT tighten at this time. Refer to Figure 9.
Detail A
1" Mast/Capacitor Clamp
Detail B
3/8" x 1" x 3/8" Mast/Capacitor Clamp
Figure 7
30 Meter Trap Assembly
ATTACHING UPPER RADIATOR
TUBES TO 30 METER TRAP ASSEMBLY
Select the 30 meter trap assembly, 7/8" x 36"
tube (Item 11), 5/8" x 48" tube (Item 10),
7/16" x 55" tube (Item 2), and the two #6
tubing clamps (Item 21). Assemble as shown
in Figure 8. Dimensions H and I will be set
later on in the instructions. Tighten all
hardware and clamps except for the middle
tubing clamp.
Push a caplug (Item 34) on the top end of the
55" x 7/16" tube (Item 2).
Figure 8
Upper Radiator Tubes Attached to
30 Meter Trap Assembly
INSTALLATION OF TUBING
CLAMPS
Select the proper size tubing clamp as shown
in the chart. When installing the clamps, place
the clamp near the tube end with the top of the
clamp over the slot in the tube as shown in
Figure 9.
Part
No.
358756
After adjustment of the tubing lengths, tighten
the clamp with a 5/16 inch nut driver, socket,
or open end wrench until the tubing will not
twist or telescope.
Description
Fits
Tubing
Sizes
Clamp, Size #6
all stainless steel
1/2
and 3/4"
5/16" hex head screw
Part
Description
No.
358757
Fits
Tubing
Sizes
Clamp, Size #10
all stainless steel
1"
5/16 hex head screw
Part
Description
No.
358758
Fits
Tubing
Sizes
Clamp, Size #16
all stainless steel
5/16 hex head screw
Figure 9
Tubing Clamps
1 1/4"
ATTACHING THE
TRAP ASSEMBLIES
Slide the bottom end of the 30 meter trap into
the top end of the 17/20 meter trap assembly.
Dimension H will be set later on in the
instructions. DO NOT tighten now.
Select the 11/4" x 61/4" slotted tube splice
(Item 6), and the two #16 tubing clamps (Item
23) . Assemble as shown in Figure 8. The
bottom of the 17/20 meter trap assembly and
the top of the 10/12/15 meter trap assembly
should meet within this tube.
Tighten both tubing clamps securely.
Select the 13/8" x 9 3/4 drilled tube splice
(Item 7), four # 10-24 x 13/4 inch bolts (Item
25), four #10 lockwashers (Item 33), and four
# 10-24 hex nuts (Item 28). Assemble this
tube as shown to join the bottom of the
10/12/15 meter trap assembly to the top of the
80/40 meter tuning assembly. Tighten all
hardware securely.
Select the base assembly and attach to the
bottom of the 80/40 meter tuning assembly
using two 10-24 x 13/4 inch bolts (Item 25),
two #10 lockwashers (Item 33), and two # 1024 hex nuts (Item 28). Tighten all hardware
securely.
DC SHORTING COIL
The VSWR on the 40 and 80 Meter bands may
be improved by the construction and
installation of a matching coil. This coil will
also provide a DC ground for the antenna,
which may help to prevent precipatation
static. This coil is included in the GRK-88
A coil consisting of 9 or more turns of No. 12
insulated copper wire should be wrapped on a
1 inch diameter coil form and connected
between the radiator and the ground (shunt).
If this antenna is modified to operate on 160
meters, this coil may be replaced with another
coil of the proper value.
NOTE: The long 80/40 meter tuning
capacitors and the 10 meter capacitor may be
loosened and rotated to allow assembly or
prevent mechanical interference problems
between them and the 10 meter capacitor.
Tighten all hardware securely. See top views
in Figure 12.
Figure 10
DC Shorting Coil
Figure 11
Connecting Trap Assemblies
TUNING THE DX-88
VERTICAL ANTENNA
Decide if you want to tune the DX-88 vertical
for the 8 HF amateur bands or whether you
wish to tune it for reception on the
international shortwave broadcasting bands.
Also, if you choose the amateur band settings,
you must also choose a setting for either 80
meter CW (3500 - 3800 KHz) or 75 meter
"phone" (3700 - 4000 KHz). Although the
DX-88 may be tuned from 3500 to 4000 KHz
at the base of the antenna, the narrower 40
meter band (7000 - 7300 KHz) tracks along
with the same adjustment. The 5/8 inch tubing
near the tip of this antenna (dimension I)
should be set to 18 inches if you operate
mostly on CW on both 40 and 80 meters.
Dimension I should be set to 28 inches if you
operate mostly on phone on both 40 and 80
meters.
If you wish to use a tuner or matchbox to
cover all of the 80 meter band, choose either
the CW or phone setting and tune the long
capacitors to favor the right part of the 40
meter band. You may then switch the tuner to
the "thru" setting for 40-10 meters.
You may install the DX-88 on the ground, on
a rooftop or on a mast. If installed on the
ground, the supplied dimensions will be
accurate only if the GRK-88 ground radial kit
is used, or if a radial system is constructed
identical to the GRK-88. Each of the bands,
30 meters through 10 meters, may be tuned
individually to favor a particular part of each
band. On 30 meters, dimension H may be
lengthened to lower the resonance or
shortened to raise the resonance on each band.
On the other bands, more capacitance (tubing
pushed in) will lower the resonance, and less
capacitance (tubing pulled out) will raise the
resonance.
If installed on a rooftop, the supplied dimensions will be accurate only if the RRK-88 roof
radial kit is used or if a radial system is constructed identical to the RRK-88. Each of the
bands, 30 meters through 10 meters, may be
tuned individually as described previously.
Also, each band may be tuned by adjusting
the lengths of the corresponding radials.
This may be easier to achieve on some roof
tops. Mast mounting is the same as roof top
mounting.
A radial system is always required with this
antenna. The only exception might be when
the antenna is installed on a saltwater beach
with a ground rod.
If you choose to tune the DX-88 for SWL
operation, you may optimize the antenna for 8
bands. Other bands of frequencies may still be
received by this antenna, but at reduced signal
strengths. Adjust dimensions A through T
according to these tables and graphs or from
the dimensions supplied in the examples. See
Figure 12.
EXAMPLE I - Amateur
The dimensions for this antenna to resonate
in the center of each amateur band are:
EXAMPLE 2 - SWL
The dimensions for this antenna to resonate
in the center of the 11, 13, 16, 19, and 31
meter SWL bands, and near the 49 and 90
meter SWL bands are:
Graph 1
Sum of Dimension A and B
80/40 Meter Trap for 6.9-7.4 MHz
Graph 2
Sum of Dimension A and B
80/40 Meter Trap for 3.5-4.0 MHz
Graph 3
Dimension C
10 Meter Trap for 27-29.7 MHz
Graph 4
Dimension D
12 Meter Trap for 245-26.5 MHz
Graph 5
Dimension E
15 Meter Trap for 20.5-22 MHz
Graph 6
Dimension F
17 Meter Trap for 17.5-18.5 MHz
Graph 8
Dimension H
30 Meter Trap for 9.5-10.5 MHz
Graph 7
Dimension G
20 Meter Trap for 13.5-15.5 MHz
SETTING
HAM - CW
DIMENSION
DIMENSION
"H"
"I"
16 in.
18 in.
19 in.
28 in.
25 in.
46 in.
HAM-PHONE
AND
S WL 41/75 METERS
S WL
49/90 METERS
Table 1
Dimension H and I for HAM
and SWL Settings
The following high frequency bands have been allocated by the
International Telecommunication Union to be used for broadcasting:
kiloHertz
2,300-2,495
3,200-3,400
3,900-4,000
4,750-5060
5,900-6,200*
7,100-7,350*
9,400-9,775*
9,775-9,900
11,600-11,700*
11,700-11,975
11,975-12,100*
13,570-13,870*
15,100-15,450
15,450-15,800*
17,480-17,700*
17,700-17,900
18,900-19,020*
21,450-21,750
21,750-21,850
25,600-26,100
MegaHertz
Band
2
3
4
5
6
7
9
9
11
11
11
13
15
15 .
17
17
19
21
21
26
Meter
Band
120*
90*
75**
60*
49t
411 -#
31r-*
31$
25v
251'
25t
22$
19t
19f
16v
16t
16t
13t
13$
lit
• Tropical bands, for broadcasting use in designated tropical areas.
• ** Regional band used only in Europe and Asia.
World Bands, used worldwide.
World Band extensions. Not yet officially authorized, but being used by an
increasing number of broadcasting stations.
# Not used for broadcasting in the Western Hemisphere.
Includes Amendments to Article 8, The Int. Table of Frequency Allocations,
effective April l, 2007.
Many stations use frequencies outside of, but adjacent to the bands listed
above.
Table 2
Broadcasting Frequencies
TOP VIEW
TOP VIEW
Figure 12
DX-88 Overall View
CHAPTER 4
MOUNTING THE ANTENNA
The Omni DX-88 vertical can be mounted on
the ground, on a rooftop or on a mast. For
best performance, it should be mounted in the
clear, at least 20 feet from buildings, metal
fences, metal masts or flag poles and other
metallic structures.
WARNING
DO NOT install this antenna near any power
lines. Not only is it dangerous to put up and
take down, the power lines could cause
excessive noise to be received by the radio
connected to this antenna.
If the DX-88 is installed on the ground, a
radial system is normally required. The
minimum recommended radial system
consists of 16 radials, each 14 feet (4.3 m)
long. See Figure 13.
Installation of this product near power
lines is dangerous! For your safety,
follow the installation directions.
Figure 13
DX-88 Ground Mount Radial System
Since the radials of a ground-mounted
vertical are actually on, if not in, the ground,
they are coupled by capacitance or
conduction to the ground, and thus resonance
effects are not important. Basically, the
function of ground radials is to provide a lowloss return path for ground currents. Longer
radials and more radials will reduce the
ground losses and effectively increase the
gain of the antenna. See the article entitled
"Radial
Systems
for
Ground-Mounted
Vertical Antennas" by Brian Edward, pages
2830, QST magazine, June, 1985 for more
information.
It is recommended to use copper wire or
copperweld wire for the radials. The Hy-Gain
ground radial kit, model GRK-88 uses 7/23
Copperweld© wire. The wires may be
soldered to lugs and attached to the bottom of
the base bracket.
If the DX-88 vertical is installed on a garage
or house roof, a resonant radial system must
be used. The Hy-Gain model RRK-88 roof
radial kit may be used or you may construct a
radial system identical to it. See Figures 14
and 15.
Figure 14
DX-88 Resonant Radial System
Copperweld is a registered trademark of Copperweld
Group
RESONANT RADIAL LENGTHS
AMATEUR BAND
WIRE LENGTH
SWL BAND
WIRE LENGTH
(METERS)
U.S.
METRIC
(METERS)
U.S.
METRIC
41/40
30
20
17
15
12
34'2"
23'9"
17'1"
13'8"
11,111,
10'3"
10.41 m
7.24 m
5.21 m
4.17 m
3.63 m
3.12 m
31
22
19
16
13
11
25'1"
17'10"
16'0"
13' 10"
11'5"
9'7"
7.65 m
5.43 m
4.87 m
4.23 m
3.47 m
2.92 m
10
9' 1"
2.77 m
Table 3
Resonant Radial Lengths
NOTE:
The radial wire lengths may be adjusted longer or
shorter to fine-tune the resonant frequency on each
band
Figure 15
Roof Mounted Radial System
WARNING
Keep this antenna away from the reach of
children or pets. When transmitting, the
antenna and antenna radials are hot with RF
proportional to the operating power.
If you mount your antenna on a roof and find the
roof space is too small for the radial system, you
can droop the radials over the edge of the roof at
almost any angle without seriously changing the
p-Irformance of the antenna. The radial system
must be insulated from the roof and connected to
a good ground for lightning protection. The
resonant radials must be at least 10 feet from
tower guy wires, mast guy wires or any other
wires or metal objects. Use the shortest path
possible between the antenna and an 8 foot
ground rod for the earth ground, using #6 or #8
copper wire. Mast mounting is identical to roof
mounting.
In any installation, use a good quality 50 ohm
coaxial transmission line such as Times RG213/u (solid), Belden 8214 (foam) or Belden
8237, 8267 or 9251 (solid).
Take extra care when soldering connectors to
foam dielectric coaxial cable. Weatherproof all
connectors which will be exposed to rain or ice
with Coax-Seal
or
another
similar
substance.
Attach the transmission line to the bottom of the
base assembly and tighten securely. Tape the
coax to the tripod for strain relief when roof
mounting. Bury the coax, when ground mounting,
for protection from lawn mowers.
CAUTION: Align the bottom tube of the DX-88
antenna parallel to your support mast before
tightening. Your support mast must be 1 1/2" - 1
5/8" (38-41 mm) O.D. Tighten the U-bolts
_securely using open-end wrenches! If one Ubolt is loose, the bracket will twist.
OPERATION
Connect the other end of your transmission line
to a good quality SWR meter and then to your
transmitter. While using low power (less than
200 watts output) check the VSWR across each
band from 3.5 to 29.7 MHz. Record this
information for future reference. See Table 4.
Check the VSWR periodically to ensure proper
operation.
This completes your installation of the Omni DX88.
Service Information
If you are unable to resolve your problem or if you
need to order replacement parts, you should contact
the Hy-Gain Customer Service Department.
You should fully research your problem by going
through the Troubleshoting Guides in Chapter 6
before you contact the Customer Service
Department. You should also record your VSWR
across all three bands before calling
You should retain your sales receipt or other proof
of purchase for antennas that are still under
warranty.
All requests, inquires, warranty claims, or
for ordering replacement parts, contact:
Hy-Gain
308 Industrial Park Road
Starkville, Mississippi
39759 USA
Phone: 662-323-9538
FAX: 662-323-6551
RIGHT
WRONG
VSWR RECORD
Type of VSWR Meter
Date_____________ Date______________ Date____________
Frequency
3.
7.000
7.150
7.300
10.100
10.150
14.000
14.200
14.350
18.068
18.168
21.000
21.250
21.450
24.890
24.990
28.000
28.400
28.800
29.600
VSWR
VSWR
VSWR
CHAPTER 5
PARTS LIST
Item
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
174865
174939
179764
179767
179768
179771
179772
179782
179783
190000
190210
878202
878204
878532
878536
878537
878539
179734
179735
179736
179737
358756
358757
358758
543792
878541
500321
500158
505266
554071
554099
555747
562961
564792
565697
878542
455644
460367
460368
878548
Tube, 7/16" x 48".................................................................................. 2
Tube, 7/16" x 55"..................................................................................1
Tube, 1" x 45" ....................................................................................... 2
Tube, 1" x 16" ....................................................................................... 2
Tube, 1" x 13" ....................................................................................... 3
Splice, 11/4" x 6 1/4", slotted .............................................................1
Splice, 13/8" x 9 3/4", drilled..............................................................1
Tube, 7/16" x 19"..................................................................................2
Tube, 7/16" x 16"..................................................................................3
Tube, 5/8" x 48", swaged ..................................................................... l
Tube, 7/8 x 36", swaged.......................................................................1
Coil Assembly, 17/20 Meter ..............................................................1
Coil Assembly, 10/12/15 Meter......................................................... l
Coil Assembly, 80/40 Meter ..............................................................1
Coil Assembly, 30 Meter....................................................................1
Base Assembly.................................................................... ..........1
_
Clamp, Mast/Capacitor, 11/8" x 1................................................ 14
Clamp, Mast/Capacitor, 11/8" x 7/16".........................................14
Clamp, Mast/Capacitor, 1"..............................................................2
Clamp, Mast/Capacitor, 3/8" x 1" x 3/8"......................................... 2
Clamp, #6 Tubing, stainless steel ......... A....................................... 2
Clamp, #10 Tubing, stainless steel................................................ l
Clamp, # 16 Tubing, stainless steel................................................ 3
U-bolt, 5/16" x 15/8" x 2 1/4" .......................................................... 2
Parts Pack, DX88 Hardware .............................................................1
Bolt, # 10-24 x 13/4", hex head, stainless steel ............................ 6
Bolt, # 10-24 x 1/2", hex head, stainless steel ............................. 50
Bolt, 1/4"-20 x 3/4", hex head, stainless steel ................................ 3
Nut, #10-24, hex, stainless steel ..................................... :............ 56
Nut, 1/4"-20, hex ............................................................................... 3
Nut, 5/16"-18, hex, stainless steel................................................... 4
L.ockwasher, 1/4", internal, stainless steel .................................... 3
L.ockwasher, 5/16", split, stainless steel......................................... 4
L,ockwasher, #10, internal, stainless steel.................................. 56
Parts Pack DX88, Insulators..............................................................1
Caplug, 7/16", black ......................................................................... 9
Insulator, 7/16" x 7/8", spacer........................................................ 21
Rain Cap, 1„ ID ................................................................................ 7
Capacitor Assembly, 30 Meters ........................................................ 2
LIMITED WARRANTY
Hy-Gain Warrants to the original owner of this product, if manufactured by Hy-Gain
and purchased from an authorized dealer or directly from Hy-Gain to be free from
defects in material and workmanship for a period of 12 months for rotator products and
24 months for antenna products from date of purchase provided the following terms of
this warranty are satisfied.
1. The purchaser must retain the dated proof-of-purchase (bill of sale, canceled check,
credit card or money order receipt, etc.) describing the product to establish the
validity of the warranty claim and submit the original or machine reproduction of
such proof of-purchase to Hy-Gain at the time of warranty service. Hy-Gain shall
have the discretion to deny warranty without dated proof-of-purchase. Any evidence
of alteration, erasure, or forgery shall be cause to void any and all warranty terms
immediately.
2. Hy-Gain agrees to repair or replace at Hy-Gain’s option without charge to the
original owner any defective product under warranty, provided the product is
returned postage prepaid to Hy-Gain with a personal check, cashiers check, or
money order for $8.00 covering postage and handling.
3. Under no circumstances is Hy-Gain liable for consequential damages to
person or property by the use of any Hy-Gain products.
4. Out-of-warranty Service: Hy-Gain will repair any out-of-warranty product
provided the unit is shipped prepaid. All repaired units will be shipped COD to
the owner. Repair charges will be added to the COD fee unless other
arrangements are made.
5. This warranty is given in lieu of any other warranty expressed or implied.
6. Hy-Gain reserves the right to make changes or improvements in design or
manufacture without incurring any obligation to install such changes upon any of
the products previously manufactured.
7. All Hy-Gain products to be serviced in-warranty or out-of-warranty should be
addressed to hy-gain,
308 Industrial Park Road,
Mississippi 39759, USA and must be accompanied by a letter describing
the problem in detail along with a copy of your dated proof-of-purchase.
8. This warranty gives you specific rights, and you may also have other rights which
vary from state to state.