• Broadband design for full FM broadcast band coverage
• 75 ohm cable connections for easy hookup and low cost
• Simple, heavy duty PVC construction for a durable antenna
that will last for years and years
• Designed for use with either transmitters or receivers
• Helps to increase transmission distance by providing a
better radiator than just “hanging wires”
• Reduces hum problems by reducing reflected RF power into
micro-transmitters
• Mountable in either horizontal or vertical position for easy
polarization selection
Here’s the ultimate radio antenna for your micro-power
transmitters and high sensitivity receivers. Maximum power
radiation is assured by proper impedance matching and
computer design. Greatly increases transmission range! Use
what the professionals use, step up to the pump and increase
your coverage!
Ramsey Electronics Model No. TM100
TM100 Page 2
RAMSEY TRANSMITTER KITS
• FM100B Professional FM Stereo Transmitter
• FM25B Synthesized Stereo FM Transmitter
• MR6 Model Rocket Tracking Transmitter
• TV6 Television Transmitter
RAMSEY RECEIVER KITS
• FR1 FM Broadcast Receiver
• AR1 Aircraft Band Receiver
• SR2 Shortwave Receiver
• SC1 Shortwave Converter
RAMSEY HOBBY KITS
• SG7 Personal Speed Radar
• SS70A Speech Scrambler
• BS1 “Bullshooter” Digital Voice Storage Unit
• AVS10 Automatic Sequential Video Switcher
• WCT20 Cable Wizard Cable Tracer
• LC1 Inductance-Capacitance Meter
RAMSEY AMATEUR RADIO KITS
• DDF1 Doppler Direction Finder
• HR Series HF All Mode Receivers
• QRP Series HF CW Transmitters
• CW7 CW Keyer
• CPO3 Code Practice Oscillator
• QRP Power Amplifiers
RAMSEY MINI-KITS
Many other kits are available for hobby, school, Scouts and just plain FUN. New
kits are always under development. Write or call for our free Ramsey catalog.
TM100 FM ANTENNA INSTRUCTION MANUAL
Ramsey Electronics publication No. MTM100 Revision 1.1a
First printing: May. 1996 MRW
COPYRIGHT 1996 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. Printed in the United States of America.
TM100 Page 3
TM100 TRU MATCH
FM BAND ANTENNA
Ramsey Publication No. MTM100
Price $5.00
TABLE OF CONTENTS
Introduction .....................................4
How Does It Work? .........................4
Learn As You Build .........................5
Parts List .........................................7
Construction ..................... ...............8
Testing ..........................................13
Setup ............................................14
KIT ASSEMBLY
AND INSTRUCTION MANUAL FOR
TM100 Page 4
INTRODUCTION TO THE TM100
At Ramsey Electronics we are constantly bombarded with questions on how to
get the micro power transmitters to go as far as possible without worry about
FCC rules being broken. Here is the answer all you callers and others
interested in getting the most out of the FM micro-transmitters. We have come
up with a sturdy, easy to build folded dipole antenna with wide band
characteristics perfect for transmitting or receiving.
HOW DOES A FOLDED DIPOLE ANTENNA WORK?
A folded dipole antenna is a pair of wires that are suspended between two
points. The wire is cut to a specific length, and is fed in the middle with a radio
frequency (RF) signal. In our case the folded dipole has an impedance of
around 300 ohms, while we are using 75 ohm cable to feed it. We use what is
called a matching transformer to convert the impedance from 75 ohms to 300
ohms, which also gives us a better bandwidth where the antenna is efficient at.
We also add a ferrite choke core on the coaxial cable to prevent radiation along
the coax feed line. This little core really does the trick in providing a proper
match to your receiver or transmitter.
As an RF signal is applied to a piece of wire, both an electric and a magnetic
field is set up around the wire. These waves propagate through the air (or
ether!) without limit. As these magnetic and electric fields reach another
station’s antenna (or about any other metal object in its path) the exact reverse
effect takes place on our antenna that our RF signal did. The rapidly changing
fields produce an RF current that your receiver can detect.
Although it is impossible to actually see the waves coming off of a dipole, we
can try to visualize it to understand it better. Take a piece of paper and push a
pen or pencil through the center. Hold it up in front of you. Let’s pretend that the
pencil represents our antenna, and the paper represents where our signal is
concentrated. As you can see, most of the radiation is given off at a 90 degree
angle to the antenna, with very little radiation occurring parallel to the pencil. It
is this property that makes the dipole directional. Another advantage is that the
radiation is at all angles around the wire, causing the antenna to cover all
directions.
If you have any questions, there are many excellent books on antennas
available at any good electronics store. The classic ARRL Radio Amateur
Handbook is also an excellent resource on antennas.
TM100 Page 5
RAMSEY “LEARN-AS-YOU-BUILD” ASSEMBLY STRATEGY
Be sure to read through all of the steps, and check the boxes as you go to be
sure you didn't miss any important steps. Although you may be in a hurry to see
results, before you switch on the power check all wiring and capacitors for
proper orientation. Also check the board for any possible solder shorts, and/or
cold solder joints. All of these mistakes could have detrimental effects on your
kit - not to mention your ego!
Kit building tips:
Use a good soldering technique - let your soldering iron tip gently heat the
traces to which you are soldering, heating both wires and pads simultaneously.
Apply the solder on the iron and the pad when the pad is hot enough to melt the
solder. The finished joint should look like a drop of water on paper, somewhat
soaked in.
Mount all electrical parts on the top side of the board provided. This is the side
that has little or no traces on it. When parts are installed, the part is placed flat
to the board, and the leads are bent on the backside of the board to prevent the
part from falling out before soldering (1). The part is then soldered securely to
the board (2-4), and the remaining lead length is then clipped off (5). Notice
how the solder joint looks on close up, clean and smooth with no holes or sharp
points (6).
Loading...