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Ramsey Electronics DA25 Instruction Manual

Broadband discone antenna kit

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BROADBAND
DISCONE ANTENNA
Ramsey Electronics Model No.
Looking for a broadband antenna with a full 360 degree
coverage? Discover what communication professionals have
known for years using a "discone" antenna. Use this antenna to
bring a multitude of signals out of the noise making it ideal for
scanners and Ultra High through Microwave Frequency
receivers! Search the airwaves for signals with this unique kit!
Omni directional performance, no need to point in any direction!
Learn about antenna theory, and what makes the discone an ideal
broadband antenna!
Covers all frequencies between 450 MHz and 2500 MHz, and you'll
learn why!
E-Z cable connection, industry standard BNC type connector.
Outperforms models costing tens to hundreds of dollars more.
Super small in size for easy mounting almost anywhere! An ideal
"apartment" size antenna!
All hardware and pre-drilled metal work included.
"Forgiving" design gives you a high performance antenna each and
every time.
KIT
DA25 • 1
DA25

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Summary of Contents for Ramsey Electronics DA25

  • Page 1 BROADBAND DISCONE ANTENNA Ramsey Electronics Model No. Looking for a broadband antenna with a full 360 degree coverage? Discover what communication professionals have known for years using a “discone” antenna. Use this antenna to bring a multitude of signals out of the noise making it ideal for...
  • Page 2 DA25 KIT INSTRUCTION MANUAL Ramsey Electronics publication No. MDA25 Rev 1.3 COPYRIGHT 2001 by Ramsey Electronics, Inc. 590 Fishers Station Drive, Victor, New York 14564. All rights reserved. No portion of this publication may be copied or duplicated without the written permission of Ramsey Electronics, Inc.
  • Page 3: Table Of Contents

    Introduction ... 4 Discone Circuit description ... 8 Parts list ... 10 Assembly instructions ... 11 Installation and Important notes .. 16 Using your DA25 ... 17 Troubleshooting guide ... 17 Warranty ... 19 Ramsey Publication No. MDA25 KIT ASSEMBLY...
  • Page 4: Introduction

    The wave in our rope example can take seconds to traverse down the length of the medium. Sound waves travel about 1100 feet every second; if we called out DA25 • 4...
  • Page 5 (“λ”) reducing our equation to λ = v x T. In English, the wavelength is equal to the velocity multiplied by the period of the waveform. Pretty neat, huh! Electromagnetic Wave One Wavelength One Cycle Some Amount of Time DA25 • 5...
  • Page 6 Looking at the desired waveform, the shortest length of wire that will resonate at a given frequency is one which is just long enough to permit an electric charge to travel from one end to the other and then back again in the time of DA25 • 6...
  • Page 7 Although we are using our discone as a receiving antenna, the rules of antenna gain are reciprocal so we can count on at least a 3 dBi improvement in the signal power over the entire frequency range. DA25 • 7...
  • Page 8: Discone Circuit Description

    The discone dimensions have been calculated such that the usable performance range is between 450 MHz to 2500 MHz with a typical VSWR of “2.0 : 1.0” or less. DA25 • 8...
  • Page 9 The DA25 kit which you are about to assemble is the non-preamplified version. The advantages to this particular model are its ease of use (no external power required) and the fact that it can just as easily be used as a transmit antenna as well.
  • Page 10 PVC coupling 3’ BNC cable RAMSEY "Learn-As-You-Build” KIT ASSEMBLY There are solder connections on the DA25 printed circuit board. Therefore, PLEASE take us seriously when we say that good soldering is essential to the proper operation of your discone antenna kit! •...
  • Page 11 DA25 DISCONE ANTENNA KIT ASSEMBLY Although we know that you are anxious to complete the assembly of your an- tenna kit, it is necessary to assemble it in a specific order to insure the proper operation of the finished unit. Try to avoid the urge to jump ahead installing components.
  • Page 12 4. Gently spread the trimmed braid to the area immediately around the P1 hole. Be sure that the braid ONLY contacts the tinned copper ground plane area around P1. Trim off any stray wires that may short circuit to the adjacent mounting rings or the center conductor solder pad. DA25 • 12...
  • Page 13 25 watt iron can provide, you may wish to use two irons or an additional heat source to speed things up. Coaxial Cable Bottom (Copper Plated) side DA25 • 13 Solder Here Solder Here Coaxial Cable...
  • Page 14 With the #6-32 nuts provided, secure the disk section of your antenna into place. DA25 • 14...
  • Page 15 Your discone antenna is now complete! Have a final look over your work, paying particular attention to the solder connections. Remember that any problems you find now can save time and effort after the unit has been mounted. DA25 • 15...
  • Page 16 Many of the metal components contained in your discone antenna will oxidize and rust if left exposed to direct weather. It is recommended that if you are planning on permanently mounting the antenna outdoors you coat the entire unit with an enamel paint before installing. DA25 • 16...
  • Page 17: Using Your Da25

    Note your signal strength indication of the station, and proceed to disconnect your existing antenna and replace it with your DA25. If your like our many satisfied customers, your notice a significant improvement in signal quality.
  • Page 18 Attn. Hobby Kit Department 590 Fishers Station Drive Victor, NY 14564 Please also feel free to visit our Website at www.ramseyelectronics.com and offer your observations to other kit enthusiasts as well. And once again, thanks from the folks at Ramsey! DA25 • 18...
  • Page 19: Warranty

    But on rare occasions a sour component can slip through. All our kit parts carry the Ramsey Electronics Warranty that they are free from defects for a full ninety (90) days from the date of purchase. Defective parts will be replaced promptly at our expense. If you suspect any part to be defective, please mail it to our factory for testing and replacement.
  • Page 20: Victor, New York

    Introduction ... 4 Discone Circuit description ... 8 Parts list ... 10 Assembly instructions ... 11 Installation and Important notes ... 16 Using your DA25 ... 17 Troubleshooting guide ... 17 Warranty ... 19 REQUIRED TOOLS • Soldering Iron •...