SHORTWAVE
CONVERTER KIT
Ramsey Electronics Model No. SC1
Fascinating listening for all ages and abilities - tunes the
world from any standard AM broadcast receiver. Put
some ‘spark’ into that commute to work or that long trip,
listen to shortwave in your car!
• Switch selectable for any two shortwave bands from 3 to 18
MHz - you pick the bands!
• Works with any AM radio - car radios are ideal!
• Tune from your regular radio dial - easily set station presets,
etc. on your existing radio.
• Operates on 9 to 15 volts.
• Listen to worldwide broadcasts in your car, boat, or home.
• Very sensitive, works as well as thousand dollar receivers!
• Great project for commuters and those who spend long hours
in the car or truck.
• Clear, concise step-by-step instructions carefully guide you
to a finished kit that not only works - but you’ll learn too!
• Add our case and knob set for a finished ‘Pro’ look. Cases
match all Ramsey products.
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RAMSEY TRANSMITTER KITS
• FM100B Professional FM Stereo Transmitter
• FM25B Synthesized Stereo Transmitter
• AM1, AM25 AM Transmitters
• TV6 Television Transmitter
RAMSEY RECEIVER KITS
• FR1 FM Broadcast Receiver
• AR1 Aircraft Band Receiver
• SR2 Shortwave Receiver
• AA7 Active Antenna
• SC1 Shortwave Converter
RAMSEY HOBBY KITS
• SG7 Personal Speed Radar
• SS70A Speech Scrambler
• SP1 Speakerphone
• WCT20 Wizard Cable Tracer
• PH10 Peak hold Meter
• 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.
SC1 SHORTWAVE CONVERTER KIT INSTRUCTION MANUAL
Ramsey Electronics publication NO. MSC1 Rev. 1.3a
First printing: July 1992
COPYRIGHT 1993 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.
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Ramsey Publication No. SC1
Price $5.00
KIT ASSEMBLY
AND INSTRUCTION MANUAL FOR
SHORTWAVE
CONVERTER KIT
TABLE OF CONTENTS
Introduction to the SC1 ........................... 4
What you can expect to hear ..................5
Parts list .................................................. 6
SC1 Parts layout .....................................7
SC1 Circuit description ...........................8
SC1 Assembly instructions .....................9
Setting up the SC1 .................................. 12
Setting your listening bands ....................13
Understanding what you're tuning ..........15
Schematic diagram ................................. 18
Ramsey Warranty ...................................19
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RAMSEY ELECTRONICS, INC.
590 Fishers Station Drive
Victor, New York 14564
Phone (585) 924-4560
Fax (585) 924-4555
www.ramseykits.com
INTRODUCTION
The Ramsey SC1 Shortwave Converter is perhaps one of the most
enjoyable, versatile and interesting radio kits you could ever build. And, since
it is exceptionally easy to build and use, it is a great kit for beginners.
Ramsey Electronics designed the SC1 especially for use with car radios. Its
flexible and practical features make it ideal for this kind of use and the
manual will explain why this is so. The other "ideal" receiver with which to
use the SC1 is a good quality AM-FM home stereo system. In fact, an SC1
converter has put fresh life into the stereo system in my own office. Even
though I've enjoyed a variety of shortwave and Ham receivers over the years,
there's nothing quite like smoothly tuning the BBC, Radio Moscow, VOA or
Paris on a quality stereo tuner and hearing it all as a big sound through highpower speakers! And you’ll have so much control over sound quality with
bass, treble, equalizing, etc.
QUESTION: What exactly is a "shortwave converter"?
ANSWER: Any receiver converter is a device which "force feeds" signals
from another frequency band into the antenna input line of a normally
complete, functioning receiver. Virtually any receiver can be converted to
receive other bands in this manner. The receiver functions as a tuneable "IF"
and its good circuit qualities carry over to the newly received frequency band
of interest. If a radio is considered to be a double conversion superhet, the
addition of a converter makes it a triple conversion superhet. Both car radios
and quality home stereos are ideal for shortwave conversion because of
their:
• excellent sensitivity
• sophisticated superhet, hi-fi receiver circuitry
• smooth, accurate dial tuning
• design for use with an external antenna
A car radio is designed to endure many bumps and engine noise. A home
stereo receiver or tuner is designed for maximum sound quality in AM-band
reception. Both are designed to be the best AM receiver circuits possible.
And since both rely on an external antenna, both are ready to use the SC1
Shortwave Converter!
A receiver designed for an external antenna is preferred for converter
operation over the typical portable or table radio with built-in antenna, since
you don't have to do anything within the radio itself for best shortwave band
performance. The SC1 may be used with a portable or table AM-band radio,
but you can expect a need for some internal connections to make sure that
the SC1 output "gets ahead" of the radio's built-in antenna. In these days
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when portable broadcast band radios are very cheap, or often available free
in various promotions, we can only suggest that you study how a particular
radio is designed and that you figure out how to get the RF output of the SC1
beyond the internal ferrite rod antenna of the AM radio. To get the most from
your SC1, we suggest that you plan to use it with a good quality AM radio
with an external antenna connection.
WHAT YOU CAN EXPECT TO HEAR
The SC1 is designed to let you easily tune in shortwave broadcasts from
around the world, using the dial of your existing AM radio for easy tuning.
These broadcasts are AM (Amplitude Modulation). You will also hear a
variety of other "interesting" sounds, but just remember that this receiving setup is designed for listening to AM style broadcast formats.
Morse code (CW) or teletype signals will probably sound like hisses or
buzzing noises. If a code signal really sounds "good", it's either because it is
being transmitted in AM-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 converter can let you tune through several
different Ham radio bands, the signals are not likely to be intelligible.
Reception of CW and SSB (single-sideband) signals requires the use of a
BFO. This is not a complicated feature, but it is beyond the purpose of the
SC1. (Hams and experimenters: please see the section for you at the end of
this manual.)
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PARTS SUPPLIED WITH THE SC1 KIT
CAPACITORS
1 4.7 or 5 pF disc [marked 4.7 or 5K] (C6)
2 100 pF disc [marked 100, 101, or 101K] (C7,C8)
2 470 pF disc [marked 470 or 471] (C2,C3)
5 .001 uF disc [marked .001, 102, or 1 nF] (C1,C4,C5,C9,C10)
2 .01 uF disc [marked .01, 103, or 10 nF] (C11,C12)
1 4.7 or 10 uF electrolytic (C13)
INDUCTORS
1 Shielded coil marked 42IF123 (L1)
1 Shielded coil marked 42EB (L2)
3 3.9 uH inductor [green body with a large silver band followed by orange-
gold-white-silver bands] (L3,L4,L5)
RESISTORS
2 470 ohms [yellow-violet-brown] (R4,R6)
2 1K ohms [brown-black-red] (R2,R5)
2 100K ohms [brown-black-yellow] (R1,R3)
SEMICONDUCTORS
3 NPN transistor type 2N3904 (Q1,Q2,Q3)
HARDWARE & MISC.
1 Ramsey SC-1 printed circuit board
2 RCA PC mount RCA jacks (J1,J2)
1 PC mount DC power jack (J3)
2 PC mount DPDT switches (S1,S2)
OPTIONAL
Matching case and knob set Ramsey model number CSC
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