Hy-Gain 18HTjr User manual

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General Description
The Hy-gain Model HT-18HTJR, High Tower Jr. is an omni-directional multiband vertical antenna. It was
designed using stub decoupling for 10 thru 80meter operation with maximum efficiency. The stubs isolate
various sections of the antenna so that an electrical ¼ wavelength exists on all bands. The High Tower Jr.
will withstand 2 KW of RF power. The maximum overall height is approximately 39 feet.
Theory of Operation
Automatic band switching of 10 thru 80 meters is accomplished in the 18HTJR by the use of stub
decoupling. In principle, a ¼ wave shorted stub is effectively an insulator, which decouples various
sections of the antenna thereby maintaining a ¼ wavelength on all bands. The 18 HTJR is fed at a current
point thus maintaining a 52ohm input impedance over an extremely wide bandwidth.
Construction
The main radiator of the 18HTJR is made up of high strength heavy walled aluminum tubing. Pre-cut
wires form a “cage” about supporting crossarms to complete the antenna.
SWR and Feedline
The 18 HTJR is designed to be fed with 52ohm coaxial cable.
RG-8A/U is recommended because of its low loss and high power handling capability. The SWR at
resonance is less than 1.2:1.
Grounding
The 18 HTJR is designed to use a simple grounding system consisting of one 8 foot ground rod as shown in
Figure 1. Radials should be used for best performance.
Installation
The 18 HTJR mounts on a piece of 1-1/4” plumber’s pipe. (Not supplied). The 1-1/4” plumbers pipe
should be at least 8’ long. Drive the pipe into the ground leaving about 20” above ground level as shown in
Figure 1.
Note: The mechanical warranty is void if the guy wires are not used. The antenna will
withstand approximately 40 MPH of wind without guys.
Before you Begin
Before you unpack the antenna, find a good location to assemble it. You will need something to
support the antenna while it is being assembled. A sawhorse or small ladder should be used to prevent the
antenna from resting on the crossarms or wires. The antenna will be 39 feet long when assembled so
moving it after it is put together might not be easy. Pick a place that you can find nuts and bolts easily
when you drop them because you WILL drop them. A few extra of the smaller hardware are included in
the parts pack so you should have some left over when you are finished.
Step-by-Step Assembly
( ) Unpack the 18HTJR and check all parts against the parts list and the illustrations. This will help you to
become familiar with the antenna and aid in assembling. The wires have been separated into packs to make
construction less confusing. Pictures of the assembly process have been used wherever possible. If you
become confused about the location or assembly of a part, some of the other diagrams later in the assembly
may be of help. Take your time assembling the antenna. You should be able to assemble the antenna by
yourself but a friend will make it much easier. When the antenna is finished you will need a friend anyway
to stand it up and mount it. Although the antenna is fairly lightweight, it is big and difficult for one person
to handle.
WARNING
Do Not install this antenna near power lines or other high voltage sources. You will be killed if
this antenna comes into contact with overhead power lines. The antenna should not be mounted
where if it fell, it would contact a power line.

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Final adjustments
The antenna now should be completely assembled. Slide the lower wire anchor bracket
down to tighten the wires and secure in place. The lower crossarm bracket should be
adjusted until the crossarm insulators just contact the 10,20,15, and 80 wires. These
crossarms keep the wires steady and tight. Install the 4 cable ties as shown in the
picture. The wires should set inside the notch cut into the insulators.
Erecting the antenna
Before you raise the antenna, double check that all hardware is tight. Find the guy rope
and cut it into 3 equal lengths. Attach the guy ropes to the guy bracket just above the
upper crossarms by threading it around the spacers and tying your favorite knot. After
the antenna is tuned, permanently secure the guy wires to suitable anchors on the ground
about 18 ft out from the base of the antenna. The antenna will stand easily without the
guy wires but are needed for permanent installation. Find a friend and mount the antenna
onto a 1-¼ plumbers pipe or equivalent (not supplied). Attach coax to the antenna by
connecting the shield braid to the mounting plate or other suitable ground. Connect the
center conductor to the main mast at the hole on the bottom of the antenna using a 10-24
x ½ bolt, nut and lock washer. Because the antenna may sag to one side during assembly
on the ground, some of the wires may not be tight when you have the antenna up.
Readjustment of the lower crossarms and lower wire anchor may be necessary.
Tunning the antenna
The antenna should be close to resonance on each band once assembled. It is best to
use an antenna analyzer such as the MFJ-259 for measurements. The antenna must be
lowered to make adjustments to the wires and tubing. Always adjust 40 meters first.
Slide the 7/16 tubing at the very top of the antenna in and out of the adjacent section to
change the resonance point on 40. Tune for the portion of the band you wish to operate.
80 Meters can be adjusted by changing where the small jumper is located on the
crossarms. Crossarm 2, 3, or 4 can be used to select a part of the band. 4 will select the
upper ssb part of 80 while 2 selects the lower cw part. Keep in mind that adjusting the
7/16 tubing at the top of the mast also affects the 80 meter tuning so a happy medium
may be needed for both bands.
The rest of the bands are adjusted by moving the insulator located at top of each wire
element. Changing where the insulator is located on the wire will electrically change the
length of the wire without physically changing it. Making the wire longer will lower the
resonant point of that band.
Install the tie in a figure 8 pattern. This will prevent the
wire from slipping out of the notch.

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Part # Qty Description
Tubing
174894 1 -- tubing, 2 x 120 x 78” swaged
174896 1 -- tubing, 2 x 81” swaged
174895 1 -- tubing, 2 x 81”
871461 1 -- tubing, 1-1/4 x 82”
172401 1 -- tubing, 7/16 x 82”
174893 1 -- tubing, 7/8 x 82”
172499 4 -- top Cross Arm, 5/8 x 36”
173346 4 -- lower Cross Arm, 5/8 x 21”
871390 1 10 Meter Wire Assembly
465416 2 -- Insulator
163312-0 2 -- Aluminum Strip,
171077 1 -- 2” tubing clamp
871464 1 -- Wire, 101 ¼”
871465 1 -- Wire, 103 ½”
871466 1 -- Wire, 20”
871408 1 15 Meter Wire Assembly
465416 1 -- Insulator
163312-0 2 -- Aluminum Strip,
871467 1 -- Wire, 122 ½”
871468 1 -- Wire, 84 ½”
871409 1 20 Meter Wire Assembly
465416 1 -- Insulator
163312-0 3 -- Aluminum Strip,
871471 1 -- Wire, 198”
871472 1 -- Wire, 5”
871438 1 80 Meter Wire Assembly
871474 1 -- Wire, 215 ½ ”
871481 1 -- Wire, 64 ½ ”
871484 1 -- Wire 2”
465416 1 -- Insulator
871475 3 -- Wire, 66 ¾ “
871478 4 -- Wire, 53 ¼ ”
871448 1 Parts Package “A”
7452158B 4 -- Black cable tie
172739 4 -- Clamp, Upper Wire Anchor
172741 3 -- Clamp, Guy Rope
173452 4 -- Clamp, Lower Wire Anchor
455644 1 -- Caplug, 7/16”
7153159 3 -- Spacer
463244 8 -- Insulator, Crossarm,
879888 1 PARTS PACK “B”
500105 1 -- bolt 10-24 x 2-1/4”
500159 1 -- bolt, 10-24 x 1-½”
500158 65 -- bolt, 10-24 x ½”
504069 6 -- bolt, 10-24 x 1”
505266 7 -- bolt, ¼-20 x ¾ ”
505736 2 -- bolt, ¼-20 x 2-¼ ”
554099 9 -- Nut, ¼-20 Hex
555747 8 -- Nut, 5/16 Hex
554071 65 -- Nut, 10-24 Hex
562961 7 -- Lock washer, ¼”
71110375EX 65 -- Lock washer, #10
564792 8 -- split washer 5/16
561177 2 -- split washer ¼”
758-9196 2 -- U bolt Saddles
5136900 4 -- U bolt
7543110S 2 -- #10 hose clamp
475500 2 Insulator, Base, 2” ID
172734 1 Base Mounting plate
172738 8 Clamp, Crossarm Bracket
878697 1 Penetrox®
635365 1 Guy rope 90 ft

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hy-gain®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.
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, Starkville,
Mississippi 39759, USAand 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.