Instruction Manual
MODEL
Thank you for purchasing our products.
For your safety :
Read this manual carefully for proper handling and operation before using.
Keep this manual in a safe place for future reference.
GP-285
【
Specifications
】
Frequency band : 135 - 175 MHz (by adjustment of element length)
Antenna type : 5/8 λ 2-stage collinear antenna
Gain : 5.15 dBi
Polarization : Vertical (omnidirectional in horizontal plane)
VSWR : 1.5 or less
Band with VSWR 1.5 or less : 2 MHz (at 135 MHz) , 4 MHz (at 175 MHz)
Band with VSWR 2.0 or less : 4 MHz (at 135 MHz) , 8 MHz (at 175 MHz)
Max.Input Power : 500 W (CW)
Lightning protection structure : DC Grounded
Overall length : Max. 3.34 m (135 MHz) , Min. 3.0 m (175 MHz)
Wind speed : Max. 50 m / s
Wind receiving load : Max. 142 N
Wind receiving area : Max. 0.115 m
2
Weight : approx. 2.3 kg (except mount bracket)
Connector : SO-239 (M-J)
【
Features
】
●This product is a 5/8λ 2-stage high gain GP antenna.
●By adjusting the element length, VHF band amateur band (144-148 MHz) was included.
It can be used in the range of 135 to 175 MHz.
●High withstand input 500 W antenna.
④ Radial element (L:430mm) … 8pcs.
COMET CO.,LTD.
4-18-2, Tsuji, Minami-ku, Saitama-shi, Saitama-Pref, 336-0026, JAPAN
TEL : 81-48-839-3131 / FAX : 81-48-839-3136
URL : http://www.comet-ant.co.jp/english
Copyright (C) 2019 COMET CO.,LTD. All Rights Reserved.
Jan.2019 1st edition. Printed in JAPAN.
VHF Band
5/8 λ 2-stage Collinear Antenna
First of all, please check whether
there are parts as per the parts list.
⑦ Radial clamp … 8pcs.
② Bottom element (L:1760mm) … 1pc.
⑤ Hose clamp (Small) … 1pc.
⑥ Hose clamp (Large) … 1pc.
① Top element A (w/ Feeding section) … 1 set
③ Top element B (L:840mm) … 1 pc.
⑧ Hex Bolt (No.10x24 5/8")… 32pcs.
⑨ Tooth Washer [Internal] (No.10)… 32pcs.
⑩ Hex Nut (No.10x24) … 32pcs.
Parts List
Assembling the bottom element part
1. Four radial clamps and four radial pipes become
one radial unit.
Temporarily assemble as shown in the fig.1 , and
combine it up and down two units.
Fig.1
Set of Radial unit.
⑪ U-Bolt … 2pcs.
⑫ Mount Bracket … 2pcs.
⑬ Hex Bolt (M6x30) … 2pcs.
⑭ Spring Washer (M6) … 6pcs.
⑮ Hex Nut (M6) … 6pcs.
④ Radial element
⑦ Radial clamp
⑧ Hex Bolt
⑨ Tooth Washer
⑩ Hex Nut
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Maintenance
】
■
If any unusual situation happens, stop using immediately and ask the local agent you purchased this product.
■
Confirm if the product works normally before operating.
■
Be sure to change the parts which have strength poverty or deformation across the ages etc.
!
PRECAUTIONS for Operation
●Do not touch the antenna while transmitting, otherwise you would get burned.
●Do not touch the antenna or coax cables while lightning. Checking VSWR after lightning is highly recommended.
●Do not use this antenna outside its specification. Failure to follow this would damage the antenna.
●Make sure to adjust the antenna in a right way. Higher VSWR could cause the performance degradation.
●Never attempt to fix or modify this antenna by yourself.
Specifications or appearance is subject to change without notice.
PRECAUTIONS for Installation
● Wearing a safety hat and a life line during installing on a roof top or any high places is highly recommended.
● Erect this antenna in a safe place Check if the Cable Connector fits into the Antenna Connector.
● Make sure all nuts, bolts and screws are securely tightened. Failure to follow this would cause a serious
accident or performance degradation.
● Check if waterproofing at each connection is appropriately done. If not, it would cause short-circuit and/or
corrosion.
● Do not erect this antenna near any electrical power lines, steel towers and/or buildings. Such objects would
cause performance degradation.
!
Vertical Beam Pattern Image
VSWR
VSWR Reference data at 144MHz
150MHz
2.0
Length : 1325 mm
Length : 870 mm
A
B
145MHz
140MHz
1.8
1.6
1.5
1.4
1.3
1.2
1.1
1.0
