Hy-Gain DX-77A Instructions

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DX-77A

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7-Band HF Vertical

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Starkville, MS 39759 USA Ph:

[phone] FAX: [phone]

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INSTRUCTION MANUAL_

General Description

The "DX-77-A" is an omnidirectional, self-sup­porting, automatic-bandswitching vertical
radiator which operates on the 10, 12, 15, 17, 20,
30 and 40 meter Amateur bands. No ground
radials are used with the DX-77-A. The DX-77-A
design is based upon an off-center-fed dipole,
sometimes called a "Windom" antenna. High­efficiency high-power traps are used to isolate
the active sections of this antenna.

Specifications

10, 12, 15, 17, 20, 30, 40-Meter

The DX-77-A uses a heavy-duty tiltable mast
clamp which will accept masts of up to 2 118"
inches O.D. The entire antenna may be easily
raised and lowered for tuning purposes and for
recreational - vehicle (RV) installations. The
DX-77-A also features an overall length of 29
feet (8.8 m), which contributes to exceptional

andwidths on 40 and 20 meters.

Electrical.

40m 7.0 - 7.3 MHz 100 KHz min.; 150' KHz typ.
30m 10.1 - 10.15 MHz 100' KHz min., 150 KHz tpy.
20m 14.0 - 14.35 MHz 200 KHz min., 250 KHz typ.

17m 18.068 - 18.168 MHz 200 KHz min., 250: KHz typ.
15m 21.0 - 21.45 MHz 400 KHz min., 500 KHz typ.

12m 24.89 - 24.99 MHz 300 KHz min., 400 KHz typ.

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VSWR' of Resonance............................. .. .....................................................less than. 1.5:1

Maximum Power (at 95° F) ............................................ 750 watts ave., 1500 watts PEP

Gain..... . ........................................unity gain (compared to half-wave vertical dipole)

Input Impedance

Total Height.……........................ ......................................................... 29 feet (8.8' m)

Bottom Radial Elements .........................................................................4 each, 5 feet (1.5 m)

Allowable Mast O.D. . ..................... ................................1.75 - 2.125 inches (44

Recommended Masts8 to 10 foot length) .....…........ Aluminum, 2 inch O.D.,

Steel, 2 inch O.D., :058 wall min.

28.0 - 29.7 MHz 1500 KHz min., 1700 KHz typ.

.......... .... .... .... .... .... .... .... .... .... ... ..... .... .... .... .... .... .... .... .... .... .... .... ...5 0 ohms

Mechanical:

-

53 mm)

.125 wall min

Weight................... ... ............................................……………………... 25 lbs. (11.35 kg:)

Wind Area . ... .... ............. ....'..............………………………........

Maximum Wind Speed (unguyed) ........................................................ 60 mph ( 96.77 Kmph)

1.9 sq. ft. (.1767 sq. m.)

Choose Location

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Choose a location for the DX-77-A in the clear,
away from trees, buildings, power-lines and other
metallic objects. The DX-77-A should be
attached to a steel mast or heavy aluminum mast
which is capable of supporting a structure of this
size. The DX-77-A does NOT utilize a ground
radial system, and the addition of ground radials
will NOT improve the performance. However,
high-conductivity ground in the immediate
vicinity will increase the gain by decreasing
ground losses.

Tools

Tape Measure, 12 feet

for

assembly, and

Required:

tuning

Nut Driver, 3/8 inch

for tuning and for assembly' of matching

unit Nut Driver, 5/16 inch

for tightening of tubing clamps

2 each 'Open-End Wrench, 1/2 inch for base

bracket assembly

2 each Open-End Wrench, 7/16 inch

for assembly of matching unit

WARNING:

Installation of this product near
power lines is dangerous! For your safety,
follow the installation instructions. Failure to

do so could result in serious or

The mast height can be from 4 feet (1.2 m) to 10
feet (3 m). The recommended height is approxi­mately 7 feet (2.1 m) . This puts the bottom
radials above eye-level and out-of-reach of most
children! A 10 foot (3 m) 2" O.D. steel mast set 3
feet (1 m) into concrete makes an ideal support.
The DX-77-A may also be mounted on a roof
tripod or on a tower structure, however, tuning
should be performed prior to installation. Since
wind survival is 60 mph, tower mounting is dis­couraged. If you guy the support mast or tripod,
use non-metallic guy ropes.

A ground wire may be connected to the mounting
brackets (Item 15) for lightning protection.

atal injury!

An adjustable wrench may be' used in place
of the open-end wrenches.

Pre-A

When unpacking your antenna, check all parts
against the parts list in the rear of this manual.
Read the instructions and study the illustrations
before beginning your assembly and installation.

The DX-77-A has been partially pre-assembled
for your convenience. Each trap assembly is
marked with a label: this label also indicates the
depth of insertion into the adjacent assembly.
The trap assemblies have frequency labels that
you can use as an approximate guide to tune
your DX-77-A to its resonant frequencies. If
these labels have worn off, or are missing, the
normal insertion depth is 3 inches (76mm)

The DX-77-A incorporates several improvements
over the original DX-77. Rain-caps are included
with the 17, 20, and 30 meter traps to prevent
detunin

from rain, ice, and snow accumulation.

Installation of Tubing Clamps

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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 t he clam p
over the slot in the tube as shown in Figure 1.

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
telesco

e.

Part Number Description Fits Tubing Sizes

Clamp, Size #6

358756 all stainless steel 1/2 and 3/4"

5/6" hex head screw

Part Number Description Fits Tubing Sizes

Clamp, Size #10

358757 all stainless steel 1"

5/6" hex head screw

Part Number Description Fits Tuubing Sizes

Clamp, Size #16

358758 all stainless steel 1 1/4"

5/6" hex head screw

Figure 1

Clamp Assembl

;

NOTE Tubing insertion depth is 3" (76 mm)

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unless otherwise noted.

Ite
No. Description No. Description

1 Tube, 7/16" x 62" 10 Tubing Section #2, 1 1/4" x 48"
3 Tube, 5/8" x 48" swaged 11 Tubing Section #1
6 Trap Assembly #3, 30 meter 24 Clamp, #6 tube
7 Trap Assembly #2, 17-20 meter 25 Clamp, #10 tube
8 Trap Assembly #1, 10-12-15 meter 26 Clamp, #16 tube
9 Tubing Section #3, 1 1/8" x 48" 27 Caplug, 7/16" black

Item

Figure 2

Overall View of DX77-A

Assembly of Antenna

If available, place two saw-horses approximately
15 feet (4.6m) apart. These will be used to support
the antenna during assembly.

Select Tubing Sections #1, #2, and #3 (Items 11,
10, and 9). Insert Section #2 into the top of
Section #1. Place a size #16 tubing clamp over the
slot in Section #1 and tighten. Insert Section #3
into the top of Section #2. Place a size #16 tubing
clamp over the slot in Section #2 and tighten. See
Figure 2 for dimensions.

Select Trap Assembly # 1 (10-12-15 meter) and a
size #16 tubing clamp. Place the tubing clamp
over the top of Section #3 and insert the Trap
Assembly #1 into the top of Section #3 to the
label. Tighten the clamp.

Select Trap Assembly #2 (17-20 meter) and a
size #16 tubing clamp. Place the tubing clamp
over the top of the #1 Trap Assembly and insert
the #2 Trap Assembly to the label. Rotate the #2
Trap Assembly so that the lower capacit or does
not touch any part of the #1 Trap Assembly.

Select Trap Assembly #3 (30 meter) and a size #10
tubing clamp. -Place the tubing clamp over the top
of the #2 Trap Assembly and insert the #3 Trap
Assembly to the label. Tighten the clamp.

Select the 5/8 x 48 inch swaged tube and #10
tubing clamp. Place the tubing clamp over the top
of the #3 Trap Assembly and insert the tube 3
inches, so that 45 inches is exposed. Tighten the
clamp. Select the 7/16 x 55 inch tube and #6
tubing clamp. Install this tube in the same manner
so that 54 inches is exposed. Tighten the clamp.

Refer to Figures 1 and 2 for assistance.

Select the four (4) radial brackets, 10-24 x 1 inch
screws, #10 internal lockwashers, 10-24 nuts, and
four (4) 5/8" x 7 1/2" tubes. Loosel y preassemble
the brackets and only 3 tubes on a flat surface first.
Place this assembly on the fiberglass portion of
Base Section #l, and finish assembling as shown in
Figure 3. The bottom of this bracket assembly
should be 1/2" above the 2" OD tubing part of

Section #1 .

NOTE: To fold this ass embly for transpo rt,
remove the outer screw from each joint.
Swivel the radial tubes up alongside the
radiator tubing. Install th e screws back into
the joint hole s and tighten for safekeeping.

Select the four (4) 7/16" x 52" tubes and four (4)
#6 tubing clamps. Place each tubing clamp over
the end of each of the 5/8" x 7 1/2" radial tubes.
Insert each of the 7/16" tubes into the 5/8" radial
tubes so that 46" (1.17 m) is exposed. Tighten all
four clamps. Place a caplug over the end of each
tube.