4-10 MHz
SHORTWAVE RADIO
Ramsey Electronics Model No. SR-1
Have you ever wanted to get into the fascinating world of radio?
The Ramsey SR-1 is a fine performer that will bring in the world
using just a few feet of wire as an antenna! Folks of all ages
have successfully built and enjoyed this easy and fun kit.
• Enjoy hours of fascinating international listening using just a simple
indoor wire antenna
• Select any 2.5MHz portion of the 4 to 10MHz shortwave band, easily
re-tuned at any time.
• Smooth varactor diode tuning
• Excellent sensitivity and selectivity
• Front panel RF Gain, Volume, and Tuning controls
• Multi-stage audio amplifier for room filling volume
• Well designed superhetrodyne circuit is easy to build, makes a nice
one-evening project
• Ideal scout, school, or club project
• Clear, concise step-by-step instructions carefully guide you to a
finished kit that not only works - but you’ll also learn too!
• Runs on a standard 9 volt battery
• Add our matching case and knob set for a finished ‘pro’ look.
Check out the excellent magazine reviews in:
√ August 1989, 73: Amateur Radio Today
√ September 1990, Popular Electronics
√ November 1991, Radio Fun
SR-1 – 1
PARTIAL LIST OF AVAILABLE KITS
RAMSEY TRANSMITTER KITS
• FM-10 FM Stereo Transmitter
• FM-25 Synthesized FM Stereo Transmitter
• AM-25 Synthesized AM Transmitter
• AM-1 AM Transmitter
RAMSEY RECEIVER KITS
• FR-1 FM Broadcast Receiver
• AR-1 Aircraft Band Receiver
• SR-1 Shortwave Receiver
• AA-7 Active Antenna
• SC-1 Shortwave Converter
RAMSEY HOBBY KITS
• SG-7 Personal Speed Radar
• SS-70 Speech Scrambler
• TT-1 Telephone Recorder
• SP-1 Speakerphone
• MD-3 Microwave Motion Detector
• PH-10 Peak hold Meter
• LC-1 Inductance-Capacitance Meter
RAMSEY AMATEUR RADIO KITS
• FX Series VHF and UHF Transceivers
• HR Series HF All Mode Receivers
• QRP Series HF CW Transmitters
• CW-7 CW Keyer
• PA Series VHF and UHF Power Amplifiers
• Packet Computer Interfaces
• 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.
4-10MHz SHORTWAVE RADIO INSTRUCTION MANUAL
Ramsey Electronics publication No. MSR-1 Revision E1
COPYRIGHT
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.
1994 by Ramsey Electronics, Inc. 793 Canning Parkway, Victor, New York
First printing: October, 1994
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SR-1 – 2
Ramsey Publication No. MSR-1
Manual Price Only: $5.00
KIT ASSEMBLY
AND INSTRUCTION MANUAL FOR
4-10MHz
SHORTWAVE RADIO
TABLE OF CONTENTS
Introduction to the SR-1 ....................................... 4
What You Can Expect to Hear ............................. 4
Shortwave Listening as a Hobby ......................... 5
Circuit Description ............................................... 6
Parts Layout Diagram .......................................... 7
Parts List ............................................................. 8
Assembly Instructions .......................................... 9
Schematic Diagram ............................................. 12
Shortwave Antenna Ideas ................................... 15
Initial Testing and Adjustment ............................. 17
Troubleshooting Tips ........................................... 19
Case, Knob and Dial Information ......................... 20
Ramsey Kit Warranty ........................................... 23
SR-1 – 3
RAMSEY ELECTRONICS, INC.
793 Canning Parkway
Victor, New York 14564
Phone (716) 924-4560
INTRODUCTION TO THE SR-1
The SR-1 is a single-conversion superheterodyne receiver designed specifically
for listening to AM broadcasting stations in the range of 4 to 10 Mhz. Because
of this "superhet" design, your favorite foreign broadcasting services will come
in loud and clear, with pleasing audio sound quality, with a minimum of
overload, frequency drift or heterodyne whistles. Because of this broadcast
oriented design, other shortwave signals such as Morse code (CW), singlesideband (SSB) voice communications and some Teletype signals will usually
sound like garbled hisses. On the other hand, similarly inexpensive receivers
designed for CW and SSB can give only marginal performance in receiving
broadcast stations due to the lack of superheterodyne design. For example, our
popular Ramsey direct-conversion receivers for the 80,40,30 and 20 Meter
Amateur bands will also pick up AM broadcast stations, but you'll mainly hear
their strong AM "carrier" signal due to the lack of the superheterodyne circuitry.
Even if such a carrier is tuned to a "null," listening fidelity is less than desirable.
WHAT YOU CAN EXPECT TO HEAR
First, let's take a look at what is POSSIBLE to hear on your SR-1. The
following are the international shortwave broadcasting bands within its tuning
range:
4.750-5.060 Mhz. (Lower power, regional "tropical" broadcasting)
5.950-6.200 Mhz (Late evening)
7.100-7.300 Mhz. (Late afternoon, early evening) (This band is always shared
with the 7.0-7.3 Mhz Amateur Radio Band)
9.500-9.900 Mhz. (Always "something" on, 24 hours a day!)
Especially strong signals include these, among others:
• BBC London: an intelligent perspective on world affairs
SR-1 – 4
• Radio Canada International: editorial quality similar to BBC
• Radio Moscow: powerful signals, increasingly honest and open
• Voice of America: VOA broadcasts are "aimed" outside the USA, but if
you're in the "path" you'll hear it loud and clear!
• U.S. Armed Forces Radio-TV "Feed" Service: master programming
source for U.S. military radio- hear CBS-NBC-ABC-Mutual news all on
the same "channel," plus many other features and spots which give a
feel for how it's going with those in uniform.
• Numerous South American stations
• USA religious broadcasting to other continents
You'll easily tune in broadcasts from many other countries as well. As you
become more and more familiar with the world of shortwave broadcasting,
you'll be deciding on your own favorite band.
You will hear a variety of other "interesting" sounds, but just remember that
this receiver is designed for AM only. If a Morse Code signal really sounds
"good," it is because it is being transmitted in AM tone-modulated form, or
perhaps the signal is so close to an AM broadcast carrier that the carrier acts
as a "beat-frequency-oscillator" (BFO). Even though this receiver can let you
tune through several different ham radio bands, the signals are not likely to
be intelligible. Reception of CW and SSB signals on an AM receiver requires
a BFO. This is not a complicated feature, but it is beyond the purpose of the
SR-1. Our companion receivers designed for the HAM bands will let you tune
into these SSB and CW broadcasts.
SHORTWAVE LISTENING AS A HOBBY IN ITSELF
Many people worldwide enjoy listening to shortwave broadcasts of all kinds,
and they keep written records of what they hear. Almost every nation on
earth has some sort of shortwave broadcast service, though many are much
more challenging to tune than the powerful signals of Radio Moscow and the
BBC. In addition, these "SWLs" (Shortwave Listeners) listen to ham
operators, government and commercial stations and even clandestine
operations. Some shortwave listeners enjoy collecting QSL cards from
stations which they have logged. Shortwave listening is, for some, a step
toward getting a ham radio license. For others, it is a great hobby in itself.
The SR-1 Shortwave Receiver is a good introductory receiver for this hobby.
After you decide exactly what kinds of listening are of the most interest to
you, you'll be a better position to choose a more elaborate receiver. While
there are various multi-band portable radios available, you can expect to pay
SR-1 – 5
at least $100 for a receiver offering a significant improvement over your
trusty SR-1.
To learn more about this SWL hobby, look for a copy of "Popular
Communications" at newsstands. An inexpensive and interesting general
introduction to all kinds of radio listening is the book, "Shortwave Listening
Guide" by William Barded, Jr. (1987; Radio Shack Catalog Number 62-
1084). This book also includes helpful introductory information about VHF
monitoring, which you can enjoy with the Ramsey FR-146 and AR-1 receiver
kits, as well as ham radio, CB, antennas, and other topics.
To learn more about Ramsey Electronics ham radio kits, write for our
complete catalog. (And, be sure to tell us how you're doing with your SR-1
Receiver!) To learn more about the hobby of ham radio, write ARRL
(American Radio Relay League), 225 Main Street, Newington, CT 06111.
CIRCUIT DESCRIPTION
The NE602 IC is a combination oscillator-mixer. Signals from the antenna
are peaked by L1 and fed to pins 1 and 2. The oscillator frequency is
determined by C3,C4,L2 and the varactor tuning network (D1,R2,etc.). The
use of a hyper-abrupt style varactor diode permits a tuning range of over 2.5
Mhz by R2. The mixer output is applied to the 260 Khz bandpass IF
transformer and amplified by Q2 and Q3. The AM audio is detected by D2
and preamplified by U2(A) before being boosted to speaker level by the
LM386 IC. U2(B) and Q1 provide AGC (automatic gain control).
The very low 260 Khz IF affords exceptional gain and selectivity
characteristics and also offers a sort of "bonus" that would not be normally
welcome in a receiver intended for communications and listening for very
weak signals. In tuning your SR-1 receiver, it is useful to understand that you
will hear any signal at the oscillator frequency PLUS 260 Khz and also at that
frequency MINUS 260 Khz. This is not a problem for general listening to
shortwave broadcasts, as long as you realize that you'll find every broadcast
twice as you pass through the 2.5+ Mhz range of the Tuning control. The
circuitry required to minimize this "image" reception would defeat the goal of
economy and simplicity intended for the SR-1. More elaborate superhet
receivers deal with this phenomenon by using a higher intermediate
frequency, several IF stages and very exact tuning of the antenna input
circuit. However, you will find the SR-1 to give perkier reception with simple
antennas than do many much more costly portable receivers.
SR-1 – 6
SR-1 PARTS LAYOUT DIAGRAM
SR-1 – 7
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