Hy-Gain TH-7DX Service manual
TABLE OF CONTENTS
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Cont.
CHAPTER 4..................................................................……............................................................4-1
Installation...........................................................................…........................................................4-1
Installation on a Crank-Up Tower............….…….…………........................................................4-1
Attaching the Antenna to the Mast ...............…………………….................................................4-1
Other Types of Towers .........................................………..............................................................4-3
Lightning Protection...............................................……….............................................................4-3
Attachment of Feedline ..........................................…….................................................................4-3
VSWR Curves.....................................................……......................................................................4-3
VSWR/Front-to-Back Charts...............................………………………........................................4-4
CHAPTER
5..............................................................................................................................................5-1
Overation ......................................................................................................5-1
CHAPTER 6.....................................................................………......................................................6-1
Troubleshooting ..............................................................……….…….............................................6-1
TroubleshootingChart..........................................……….................................................................6-1
Page
CHAPTER 7..................................................................…............……….........................................7-1
Service Information.…………...........................................................................................................7-1
Parts Identification Information.............................................……….............................................7-2
Converting American Measurements to metric ...........................................................:.................7-2
Bolt and Nut Sizes.............……….....................................................................................................7-2
Parts List....................................................................................................................................7-3
LIST OF ILLUSTRATIONS
Figure Pa
1 Boom-to-Mast Bracket ..................................................................................................3-1
2 Assembly of Boom .........................................................................................................3-2
3 Element-to-Boom. Brackets ..........................................................................................3-3
4 Tubing Clamps ................................................................................................................3-
5 Trap Detail .............................................................:........................................................3-
6 Overall View - Element Assembly and Antenna Dimensions .................................3-7
7 Rope Dampener .............................................................................................................3-8
8 Overall View of Beta Match and Phasing Tubes .......................................................3-9
9 Crossover Straps .......................................................................................................... 3-
10
11 Pigtail to Balun Connection and Front Driven Element ...................................... 3-12
12 Boom Support Assembly ........................................................................................... 3-14
13 Raising Antenna to Top of Tower ..............................................................................4-2
Pigtail Assembly to Rear Driven Element ............................................................. 3-11
DETAIL A - Beta Support Clamps and Insulator Assembly ........................... 3-12
DETAIL B - Beat Shorting Clamp Assembly ................................................... 3-12
General
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CHAPTER 4
The Hy-Gain TH7DX is a 7 element, 3 band beam
antenna designed for broadband, high performance
operation on the Amateur 10, 15, and 20 meter
bands. Broadbanding is accomplished through the
use of two fully trapped driven elements. Stainless
steel hardware and clamps are used on all
Hy-Gain's 50 ohm BN-86 balun and preformed
feed straps are supplied. The TH7DX also comes
with a wire boom support for additional strength.
The antenna is designed to fit masts from 2" to 2
1/2" in diameter and can be rotated with HyGains's
HDR-300/A, Ham IV or T2X rotators.
Projected Area is the actual (flat) projected area of either the elements or boom (highest value)
without any shape factor included. this area may be used with EIA/TIA-222-D and later versions and
with the UBC formulas to determine tower and mast loading. On HF beams, the element area is
usually higher. On VHF/UHF beams, the boom area is usually higher. When stacking HF and VHF
beams, use the element area of all beams at their attachment points to determine loading at zero
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Preparation for
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FOR OUR OVERSEAS CUSTOMERS: The
United States uses American units of measurement. Please see page 7-2 of this manual for
assistance in identifying the hardware and com-
onents supplied with this product.
Choose a large, clear area to assemble the
TH7DX. The area must be at least 24'x 31' (7.3
m x 9.5 m). You may wish to use sawhorses or
chairs to support the boom during assembly. A
concrete driveway is an excellent area for assembly. If you assemble this antenna over a
grassy area, precautions should be taken so that
hardware is not accidentally lost during assembly.
All tubing supplied with the TH7DX telescopes
together. Make all measurements to the given
dimensions, plus or minus, no more than 1/8
The TH7DX is a highly sophisticated and complex array consisting of more than 700 parts.
The superb performance engineered into this
array is totally dependent on accurate assembly.
All components and hardware must be used as
directed in the instruction manual. The key to
success is to allow yourself plenty of time.
We suggest that the assembly be done over a 2day period. We further suggest that you read this
manual thoroughly, in its entirety, then go
through the manual the second time and identify
and familiarize yourself with all of the antenna
components, and then start assembling the antenna. A few hours invested in the assembly
process will insure many years of satisfaction
When unpacking your antenna, check inside of
all tubing (traps, smaller tubing, etc.). To conserve space, these smaller articles are
sometimes put inside larger pieces. Check all
parts against the parts list to make sure no parts
are missing. The hardware supplied with this
antenna is ba
ed by thread size for your
NOTE: An extra Figure 6, Overall View - Element Assembly and Antenna Dimensions, has
been inserted in this manual for use when
assemblin
NOTE: Refer to the maintenance section on
page 5-2 for information on using anti-oxidants
and other methods of obtaining longer product
the antenna.
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Assembly of the Boom-to-Mast
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Select the boom-to-bracket clamp parts (Item Nos.
89 & 90). Loosely assemble them on the boom
ends (Item No. 79), as shown in Figure 1. Line up
the holes on both brackets and both boom ends.
Secure the two brackets together with four (4)
1/4"-20 x 3/4" bolts, lockwashers and nuts (Item
Nos. 34, 39 & 38). Secure the brackets to the two
boom ends using the 5/16"-18 x 2 3/4" bolts,
lockwashers and nuts (Item Nos. 28, 31 & 29).
Tighten these six bolts securely.
Assemble the two cast aluminum brackets (Item
No. 82) on the mast at the desired height above
your tower. Secure the two brackets together using
the two (2) 5/16"-18 x 3 " bolts, lockwashers and
nuts (Item Nos. 27,31 & 29). You may wish to drill
a 5/16" hole through the cast brackets' center hole
and through the mast and secure using a 5/16"-18 x
3 3/4" bolt, lockwasher, and nut (Item Nos. 30, 31
& 29). This bolt will prevent the antenna from
twisting on the mast in high winds. See Figure 1.
The four (4) 5 inch bolts will be installed when the
antenna is installed on the mast.
NOTE: The use of heavy motor oil on stainless
steel threads will prevent galling of threads.
Slip the two remaining boom sections (Item No.
88) over the two swaged ends of the assembled
boom and secure using a 1/4"-20 x 2 1/2" bolt,
lockwasher and nut (Item Nos. 35, 39 & 38), as
n in Figure 2
Ite
m
No.
26
27
28
29
30
31
Bolt
Bolt, hex head, 5/16"-1 8 x 3 " 39 Lockwa s he r, internal
Bolt, hex head, 5/16"-18 x 2 3/4" 79 Tube, Boom, 2" x 79 1/2"
Nut, hex, 5/16"-18 82 Mast Bracket, cast
Bolt
Lockwasher, s
Description No. Description
hex head, 5/16"-1 8 x 5 " 38 Nut, hex, 1/4"--20
hex head, 5/16"-1 8 x 3 3 / 4" 89 Clamp, Boom-to-Bracket
lit, 5/16" 90 Bracket, Casting-to-
"-
"
Figure 1 Boom-to-Mast
Assembly of the Elements-to-Boom
Front Driven
Select one pair of the largest element-toboom brackets (Item No. 85). These are
marked with a number 14. Assemble the
bracke ts on t he boom 20 i nc hes to th e l eft o f
the mast bracket (center-to-center). The
curved side of the mast bracket must be
facing you. Refer to Figure 3 for
identification of hardware. DO NOT
Rear Driven
Select another pair of the largest elementtoboom br ack ets (It em No. 8 5). As s embl e
these brackets on the boom 35 inches to the
right of the center of the mast bracket.
Refer to Figure 3. DO NOT tighten the
10-Meter Reflector:
Select a pair of the smallest element-toboom brackets (Item No. 83). These are
marked with a number 4. Assemble these
brackets on the boom 581/2 inches to the
right of the rear driven element brackets.
10-Meter Director.
Select another pair of the smallest elementto-boom bracket (Item No. 83). Assemble
these 44 1/2 inches to the left of the front
driven el em ent b rack et s. Refe r to Fig u res 3
15-Meter
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10-20 Director and 15-20
Select another pair of the smallest element-
to-boom brackets (Item No. 83). Assemble
these 371/2 inches to the left of the 10-
meter director brackets. Refer to Figures 3
and 6. DO NOT ti
hten at this time.
Select two sets of medium sized elementtoboom brackets (Item No. 84) and loosely
assemble these on the boom ends. The front
set should be 39 1/2 inches to the left of the
15meter director brackets. The rear set
should be 48 inches to the right of the 10meter reflector brackets. Refer to Figures 3
and 6. DO NOT ti
hten now.
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Item Item
No. Description
32 Bolt, hex h ead, 1/4"- 20 x 3/8"
34 Bolt, hex head, 1/4"-2 0 x 3/4"
37 Nut, square, 1/4"-2 0
38 Nut, hex, 1/4"-20 84 Bracket, Element-to-Boom, #13
No.
39
71
83
85 Bracket, Element-to-Boom, #14
Lockwasher, internal, 1/4"
Insulator, Driven Element
Bracket, Element-to-Boom, #4
Description
Figure 3 Element-to-
Boom Brackets
Remove the top anchor bolt from the 10meter director bracket. The beta tubes will be
installed over this bracket in a later ste
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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 the
clamp over the slot in the tube as shown in
Figure 4.
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. DO NOT overtighten!
Element Assembl
y
s.
To take ad van tag e of t he b road ban d nat ur e of
the TH7DX, use the su ppl i ed di mens ions as
shown in Figure 6. If assembled correctly, the
VSWR will be below 2:1 on any frequency on
these 3 bands. However, if you wish to
optimize the TH7DX for the DX portions of
these 3 bands, use the following "DX setting"
for the RDE-2 and FDE-2 dimensions:
RDE-2 = 33" (83.8 cm)
FDE-2 = 42" (106.7
Use 10-meter trap, Part Number 878749, and
15 meter trap, Part Number 878637, in this
assembly. Make sure all insulators and trap
caps are firmly seated.
NOTE:
facing the ground and the trap labels should
be on the boom s id e of th e trap . Also , on al l
tubing attached to traps, make sure all slots
are facing the ground and the small drain
holes are aligned with the slots. See Figure 5.
The drain holes and slots should be
The DX se tt in g wi ll r es ul t in min imu m
VSWR at 14.150, 21.260 and 29.000 MHz.
However, VSWR near 14.350 and 29.700 may
be slightly above 2:1. The front-to-back ratio
and gain will not change.
The following steps will be in singular form.
Do each element assembly step, first for one
side of the boom and then for the other side.
The dimensions shown in Figure 6 are in
English uni ts on th e ri ght sid e and met ri c on
the left side. After each. element is assembled
to the boom, tighten the eight (8) 1/4"-20 x
3/4" bolts (Item No. 34). After all elements
are assembles, make sure that they all lie in a
horizontal plane, then tighten the anchor bolt
Select th e FD E-1 sect io n (1 1/ 4" x 35") and a
driven element insulator (see Figure 3). Slip
the DE insulator on the unslotted end of the
FDE1, then slip the insulated end of the FDE1 into the bracket which is 20 inches to the
left of t h e mas t b ra ck et. Tig h ten th e ei gh t (8 )
bolts to hold the element in place.
Install a No. 16 tubing clamp on the slotted
end of the FDE-1 and insert the unslotted end
of the FDE-2 (11/8" x 48") to the dimension
shown in Figure 6. Tighten th e No. 16 tubing
clamp securely and recheck the FDE-2
Assemble the remainder of the Front Driven
Element in the same manner using
dimensions from Figure 6. Use Figure 5 and
Detail A as guides.
Rear Driven Element
Select the RDE -2 s ec tion (1 1/ 4" x 48" ) and a
driven element insulator. Slip the DE
insulator on the unslotted end of the RDE-1,
then slip the insulated end of the RDE-1 into
the bracket which is 35 inched to the right of
the mast bracket. Make sure the insulator
seats completely onto the tube and into the
bracket. Tighten the eight (8) bolts to hold the
Install a No. 16 tubing clamp on the slotted
end of the RDE-1 and insert the unslotted end
of the DRE-2 (11/8" x 36") to the dimension
shown in Figure 6. Tighten the No. 16 tubing
clamp securely and recheck the RDE-2
dimension. Assemble the remainder of the
Rear Driven Element in the same manner
using dimensions from Figure 6. Use Figure 5
and Detail A as guides. Use the same traps as
on the Front Driven Element.
10-Meter Reflector Element
Select the R2-1 section (7/8" x 55") and slip
the unswaged end of the R2-1 completely into
the bracket (Item No. 83) assembled on the
boom 58 1/2" inches to the right of the RDE.
Tighten the eight (8) bolts to hold the element
onto the boom
Assemble the remainder of the 10-meter
reflector as shown in Figure 6 using No. 6
tubing clamps. Tighten all element tubing
clamps with the slots facing the ground and
recheck all dimension
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