Ramsey Electronics SR2 Radio User Manual
Contents
1. 12 Schematic Diagram 14 Shortwave Antenna Ideas 20 Initial Testing and Adjustment 21 Troubleshooting Tips 23 Ramsey Kit Warranty 27 Manual Price Only 5 00 Ramsey Publication No MSR2 Assembly and Instruction manual for RAMSEY MODEL NO SR2 SHORTWAVE RADIO KIT REQUIRED TOOLS Soldering Iron Ramsey WLC100 Thin Rosin Core Solder Ramsey RTS12 Needle Nose Pliers Ramsey MPP4 or RTS05 Small Diagonal Cutters Ramsey RTS04 lt OR gt Technician s Tool Kit TK405 ADDITIONAL SUGGESTED ITEMS Holder for PC Board Parts Ramsey HH3 Desoldering Braid Ramsey RTS08 Digital Multimeter Ramsey M133 TOTAL SOLDER POINTS 166 ESTIMATED ASSEMBLY TIME Beginner 5 0 hrs Intermediate 3 0 hrs Advanced 2 0 hrs2. 8 Block Diagram 9 Parts List 10 Assembly Instructions 12 Schematic Diagram 14 Shortwave Antenna Ideas 20 Initial Testing and Adjustment 21 Troubleshooting Tips 23 Ramsey Kit Warranty 27 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR SR2 4 INTRODUCTION TO THE SR2 The SR2 is a single conversion superheterodyne receiver designed specifically for listening to AM broadcasting stations in the range of 4 to 19 5 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 single sideband 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 40 30 and 20 Meter A
3. SR2 11 HARDWARE AND MISCELLANEOUS 1 SR2 printed circuit board 2 10K potentiometers R14 21 1 DPDT PC mount push button switch S1 1 RCA type PC mount jack J1 1 Subminiature phone jack J2 1 9 volt battery snap connector 1 9 volt battery hold down clamp REQUIRED NOT SUPPLIED 9 volt alkaline or heavy duty battery Earphone small speaker or external amplifier with speaker Antenna or suitable cable connector grounding OPTIONAL Ramsey SR2 case and knob set CSR or your own enclosure SR2 12 ASSEMBLY INSTRUCTIONS In ALL PC board assembly steps our word INSTALL means to do this Insert the part oriented or pointed correctly into its holes in the PC board If helpful gently BEND the part s wire leads or tabs to hold it in place with the body of the part snugly against the top side component side of the circuit board Solder ALL wires or pins of the part Trim or nip all excess wire lengths extending beyond each solder connection taking care that wire trimmings do not become lodged in solder connections You can see that this circuit board the center portion in particular is fairly well filled with components There s more to this receiver than the average beginner s radio or even our popular Amateur Band receivers Follow the assembly instructions IN SEQUENCE and check off each step as understood and completed Some of the components require modification Examine the schematic circuit diagram an
4. ID garbled audio 9 90 RUSSIA Deut Welle relay Irkutsk nx stocks QTH ID 9 92 GERMANY Croatian R relay UK investm ts 11 60 SLOVAKIA AWR V of Hope relay ID relig nx 12 00 UNITED AE AR mx into EG 0330 nx 13 64 MADAGASCAR R Canada Int 13 65 CANADA Maple Leaf Mailbag 15 14 OMAN nx of earthquake in PNG causing tidal wave and local damage MIR space station being closed down ID mx feature on banking in Oman 16 00 AUSTRALIA VNG Time Station full ID s Only 5 kw 17 49 MADAGASCAR IBC Tamil relay ID mostly nx and tlks exc 17 67 NEW ZEALAND nx on N Ireland ID Goon Show 17 67 NEW ZEALAND classical mx In Touch with NZ featuring oldies 17 67 NEW ZEALAND nx Olympic update ID s 17 68 CHILE relig pop amp inspirational mx ID s promos SR2 25 SAMPLE SHORTWAVE LOGGINGS Con t Freq Country Notes Contributor MHz 18 96 SWEDEN Sweden Today special on Nobel prizes 18 96 SWEDEN Sweden Today article on burden of military spending on developing countries 18 96 SWEDEN Cinema Africa Film Fest being held in Stockholm 18 98 USA relig mx sermon ID SR2 26 SR2 27 The Ramsey Kit Warranty Please read carefully BEFORE calling or writing in about your kit Most problems can be solved without contacting the factory Notice that this is not a fine print warranty We want you to understand your rights and ours too All Ramsey kits will work if assembled properly The very fact that your kit includes this new manual is y
5. Your finished receiver can be installed in a variety of enclosures of your own design and choosing You might be planning to combine several Ramsey circuit kit boards in a single enclosure Use of the inexpensive and attractive Ramsey case and knob kit will give your unit that finished look and increase its resale value These sturdy black instrument cases are supplied with neatly lettered front and rear panels knobs rubber feet and mounting screws OTHER ENCLOSURE RECOMMENDATIONS While we believe that the Ramsey enclosure and knob option is a fine value for finishing off your Ramsey receiver or transmitter we are happy to give you a couple of additional suggestions and our reasons for them If your first goal is economy and rugged portability you will find that the circuit board can be mounted nicely in a standard VHS videotape storage box which also gives room for a speaker or earphone storage and even a roll of antenna wire The controls are easily mounted at one end of such a box It may be necessary to cut away the molded posts which secure the tape cassette itself These storage boxes come in several styles so pick one which looks truly practical as a project enclosure To accomplish RF shielding the most economical metal enclosure nicely suited for Ramsey kit boards is Radio Shack No 270 253A This metal utility cabinet can accommodate both a receiver and our AA 7 Active Antenna plus speaker with room for various refinements you might
6. 60 Install R16 270 ohm red violet brown PROGRESS SUMMARY Now is a good time to take a break Examine your work so far checking things such as component values parts placement and solder connections Remember the old adage The bigger the glob the better the job does not hold true with RF electronics To this point we have assembled a majority of the receiver The RF LO IF and Demodulator sections have been built leaving us with the final audio stage RSSI circuit and AGC circuit Sound like a lot more work Not at all we are going to take advantage of today s power packed ICs The LM386 audio chip takes care of our audio needs while the LM358 opamp is used two fold in the RSSI and AGC circuits 61 Install C29 1 F ceramic disc capacitor marked 1 or 104 62 Install U1 the LM358 8 pin IC Do not confuse it with the other IC read the chip marking carefully You will notice a notch band or dot on one end of the IC This should be oriented as shown on the parts layout diagram and PC board silkscreen Be sure the part is seated close to the PC board before soldering all 8 pins 63 Install R17 1K ohm brown black red 64 Install R18 also 1K ohm brown black red 65 Install J2 the subminiature speaker headphone jack 66 Install C12 1 F ceramic disc capacitor marked 1 or 104 67 Install R15 2 ohms red black gold 68 Next install U2 the LM386 audio amplifier IC As with U1 orient the notched o
7. Ramsey Electronics Model No SR2 Enjoy hours of fascinating international listening using just a simple indoor wire antenna Select portions of the 4 to 19 5 MHz shortwave band easily re tuned at any time Smooth varactor diode tuning Excellent sensitivity and selectivity Front panel 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 Have you ever wanted to get into the fascinating world of radio The Ramsey SR2 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 4 19 5 MHz SHORTWAVE RADIO SR2 2 PARTIAL LIST OF AVAILABLE KITS RAMSEY TRANSMITTER KITS FM10A FM Stereo Transmitter FM100B Professional Synthesized FM Stereo Broadcaster FM25B Synthesized FM Stereo Transmitter AM25 Synthesized AM Transmitter AM1 AM Transmitter RAMSEY RECEIVER KITS FR1 FM Broadcast Receiver AR1 Aircraft Band Receiver AA7 Active Antenna SC1 Shortwave Con
8. basic circuit theory is easy to understand The full schematic pg 14 shows the details concerning specific operation and component variable configurations Take a moment and examine the circuit block diagram found on page 9 The simplified signal flow of the block diagram shows the basic sections of the receiver The corresponding components are noted under each main block and can be cross referenced to the schematic The start of our circuit begins with the Antenna RF Signals Fc carrier frequency from the Antenna are applied to the RF Input and Filtering allowing only the signals of interest to pass through The high pass filter helps eliminate unwanted signals picked up by the antenna improving the overall reception quality of the radio After the input signal is filtered it moves to the Mixer stage Notice on the diagram that there are two inputs to the mixer We have discussed one of these input signals coming into the mixer but not the other as of yet Drop down to the Local Oscillator block The local oscillator LO for short acts as your tuning control for what frequencies you can receive by generating a signal on the board close in value to that which will be used by the mixer There is a direct relationship between the generated frequency of the local oscillator LO and the exact receive frequency Fc you want to listen to This will become clear when we finish discussing the block diagram The LO section is a Colpitts oscillator that
9. like to add such as power supply or larger battery pack etc A TUNING DIAL If you use your own enclosure and knobs you will probably plan some sort of dial markings If you finish your receiver with the Ramsey custom case and knob kit you may wish to copy one of the following designs to make a logging scale SR2 24 SAMPLE SHORTWAVE LOGGINGS Freq Country Notes Contributor MHz 4 30 PERU ballads huaynos brief annmt TC partial ID tnx 4 31 DIEGO GA oldies good sig 4 38 PERU long talk rel talk choir poor 4 40 BOLIVIA romantic vocals poor 4 72 S VIETNAM VT pop tunes YL anncr instl mx 4 72 MYANMAR soft vocals ID nx 4 78 GUATEMALA ID nx 4 78 MALI FR Spice Girls Afr pop 4 82 BOTSWANA lang church svc choir 4 82 HONDURAS cmtry mx 4 97 UGANDA tribal singing SH talk ID during nx 5 04 PERU pop mx ID phone talk 5 50 ETHIOPIA flute mx annmts nx 5 67 PERU Magnificent 7 song poss ID 5 76 GUAM AFN sports pgm PSAs 6 01 MEXICO Mexico City in SP 1005 U S oldies and SP tunes 6 02 UZBEKISTAN mx pgm ID s tlk on scientific forum 7 11 THAILAND patriotic sounding songs Asian rock mx 7 12 ITALY ID mailing QTH tlk on drug use mx 7 12 ITALY nx in EG re Columbus 2000 project ID 8 45 CHINA V of Russia relay Moscow Mailbag nx of Russia 9 02 IRAN nx re OPEC ID fqy sked 9 34 ISRAEL Kol Israel HB 2142 discussion US oldies 9 90 BULGARIA Sofia in RS 1840 tlk regional mx ID 9 90 EGYPT EG version of AR poem chants
10. long as the proper relationship between Fc and the LO exists the IF value will stay constant Due to the fact that the IF frequency stays the same all the time the Intermediate Frequency Filter can be very narrow The filter will remove any other signals coming from the mixer that are not in the proper pass band and yield a clean signal for further processing The next stage is an Amplifier with an adjustable gain feedback loop The gain control is dependant on the amount of signal being received this Automatic Gain Control AGC will be covered in a moment The amplifier boosts the signal level of the incoming IF and gives us a stronger signal to work with After the amplifier stage is another Intermediate Frequency Filter This helps remove any unwanted residual signals still present and cleans up the amplified IF for a high quality signal At this point the audio signal we are trying to obtain is riding on the IF signal The Demodulator circuit finally extracts the message from the IF through a process called envelope detection Now that we have our message back in the audio realm it is directed through the audio circuitry to the speaker output Wait there are still a few sections we have not discussed The demodulated audio branches off before the audio circuitry and is used to perform some useful functions The RSSI LED Received Signal Strength Indicator Light Emitting Diode gives us a general signal level feature The stronger the sig
11. takes advantage of smooth SR2 7 varactor diode tuning The varactor D3 forms an L C Inductor Capacitor tank circuit with T3 Increasing the voltage on the varactor diode with R21 Tuning Pot increases the capacitance of D3 thus increasing the frequency output of the LO section Now that we know the two signals coming into the Mixer stage both the Fc receive carrier frequency and the LO generated local oscillator we can better cover its operation The mixer takes these input signals and performs a few very basic operations The technical explanation of how the mixer combines these signals through Fourier Series is interesting but very drawn out The point of using the block diagram however is to simplify matters Therefore the function of the mixer is to obtain the product and the sum of the input signals This means you take the input signals and merely add and subtract their values to determine what you get on the output The general formulas to use are quite simply Fc LO Mixer Output and Fc LO Mixer Output The realistic output of the mixer stage unfortunately has other signals besides the ones we want This brings us to the next stage Intermediate Frequency Filtering An Intermediate Frequency IF is a signal somewhere between the RF signal Fc we started with and the final audio message we are trying to get The desired IF we are dealing with is a fixed number such as 455 kHz As
12. S The type of antenna you ll want to use for your SR2 depends on the degree of interest you have in shortwave listening whether you are limited to an indoor or balcony antenna and whether you think you may soon want to obtain a HAM radio license If the latter is true you may want to consult HAM radio literature and build the dipole or vertical antenna which you also plan to use for HAM listening and transmitting A 40 meter 7 MHz antenna is quite nice for the tuning range of the SR2 The rest of these notes on antennas are for the benefit of SR2 builders who simply wish to enjoy some shortwave broadcast listening The SR2 is very sensitive so its antenna requirements are minimal for casual evening listening when international broadcast signals are quite strong 10 to 20 feet of insulated hookup wire can be neatly strung behind furniture and curtains for an adequate indoor antenna The same length of wire or more outdoors or up in the attic will be an even better receiving antenna 1 The ideal antenna setup for this frequency range is considered to be an outdoor wire 25 to 50 feet in length with the ground side of the antenna jack connected to a copper cold water pipe 2 For convenience a short length of audio cable with pre wired RCA plug is adequate for making antenna and ground connections RF coaxial cable is not essential for this application 3 A banana plug may also be plugged into the antenna jack but will not SR2 20 pr
13. TORS 1 10 pF ceramic disc capacitor marked 10 C30 1 47 pF ceramic disc capacitor marked 47 C15 4 100 pF disc capacitor marked 100 101 or 100K C5 15 16 17 1 330pF disc capacitor marked 330 or 331 C2 6 001 F disc capacitors marked 001 102 or 1nF C1 3 16 20 21 25 1 0039 uF disc capacitor marked 392 or 392K C31 4 01 F disc capacitors marked 01 103 or 10nF C4 6 8 28 6 1 F ceramic disc capacitor marked 1 or 104 C7 10 12 18 19 29 2 1 F electrolytic capacitors C9 24 3 10 F electrolytic capacitors C11 22 23 2 220 F electrolytic capacitors C13 14 1 1000 F electrolytic capacitor C26 INDUCTORS 2 1 H inductors looks like a resistor with brown black gold bands L1 L2 1 12 H inductor looks like a resistor with brown red black bands L3 2 Shielded can inductors marked 42IF 103 T1 2 1 Shielded can inductors marked 42IF 123 T3 RESISTORS 1 2 ohm red black gold R15 1 100 ohm brown black brown R26 3 270 ohm red violet brown R16 22 25 8 1K ohm brown black red R3 7 9 10 13 17 18 24 5 10K ohm brown black orange R6 8 11 19 23 2 22K ohm red red orange R2 4 3 100K ohm brown black yellow R1 5 20 1 1M ohm brown black green R12 SEMICONDUCTORS 1 Red LED D2 1 1N270 diode glass bead style D1 1 Varactor diode transistor style body with two leads MVAM108 D3 3 NPN transistors 2N3904 or similar Q1 2 3 1 LM358 8 pin DIP IC U1 1 LM386 8 pin DIP IC U2
14. d PC Board parts layout diagram as you proceed Use good soldering techniques Let your soldering iron tip heat both the component lead wire and PC board trace enough so that the wire itself AND the foil trace BOTH become hot enough TOGETHER to melt a bit of solder so that it flows smoothly from the pin to the PC board trace Enough said Let s get building 1 Install S1 the DPDT push button switch Ensure that the white plastic switch extends out over the edge of the PC board and that the switch is flush to the board Solder all six pins 2 Install one of the 10K PC mount potentiometers R14 Be sure it is seated flush to the PC board then solder all 5 pins 3 Install the other 10K PC mount pot R21 Take care to seat it properly before soldering the 5 pins 4 Install J1 the RCA jack You will want to check your placement before soldering and be sure to solder all 4 tabs SR2 13 We will now begin constructing the local oscillator section 5 Install C22 one of the 10 F electrolytic capacitors Electrolytic capacitors have a right and wrong way to be installed Usually capacitors have a wide stripe which indicates their negative lead and the PC board or Parts Layout Diagram will show the positive side of the capacitor s installation hole Be sure to place the capacitor lead into the PC board hole and the lead into the hole before soldering 6 Install D3 the varactor diode marked MVAM108 This pa
15. ease be aware that a metal screwdriver blade will drastically increase the coil inductance and make adjustment quite difficult T1 and T2 are simply adjusted for strongest reception of any signal range that is tuned in If you are without any kind of testing or frequency reference equipment whatsoever the easiest way to start enjoying your SR2 is with the Tune control set at its midpoint slowly tune T3 with your alignment tool as though it were a tuning dial Stop when you come into the middle of a group or cluster of foreign broadcast stations Try tuning around these stations with the Tune control If you like what you hear readjust both T1 and T2 for best C16 001 T3 Slug In T3 Slug Out C15 None 6 5 13 0 MHz 9 0 18 3 MHz C15 47 pF 5 1 7 9 MHz 7 1 10 7 MHz C15 100 pF 4 3 5 3 MHz 6 0 8 3 MHz C16 100 pF T3 Slug In T3 Slug Out C15 None 8 4 14 2 MHz 11 5 19 5 MHz C15 47 pF 6 0 8 1 MHz 8 5 11 0 MHz C15 100 pF 4 9 6 3 MHz 6 7 8 4 MHz SR2 22 reception Eventually you will get a clue as to what general frequency band you are hearing because many stations periodically announce their frequencies particularly at sign on and sign off times If you like precision use a frequency counter or calibrated receiver to find the SR2 s strong oscillator signal remembering that there is a 455 KHz IF difference above or below between the local oscillator frequency and the broadcast s
16. ich we find excessive problems or damage due to construction methods To assist customers in such situations Ramsey Electronics Inc reserves the right to solve their needs on a case by case basis The repair is 36 00 per hour regardless of the cost of the kit Please understand that our technicians are not volunteers and that set up testing diagnosis repair and repacking and paperwork can take nearly an hour of paid employee time on even a simple kit Of course if we find that a part was defective in manufacture there will be no charge to repair your kit But please realize that our technicians know the difference between a defective part and parts burned out or damaged through improper use or assembly 4 REFUNDS You are given ten 10 days to examine our products If you are not satisfied you may return your unassembled kit with all the parts and instructions and proof of purchase to the factory for a full refund The return package should be packed securely Insurance is recommended Please do not cause needless delays read all information carefully SR2 28 SR2 Shortwave Receiver Quick Reference Page Guide Introduction to the SR2 4 What You Can Expect to Hear 4 Shortwave Listening as a Hobby 5 Circuit Description 6 Parts Layout Diagram 8 Parts List 10 Assembly Instructions
17. ignal you are hearing TROUBLESHOOTING TIPS If you experience difficulty think of your SR2 in its several sections or stages oscillator mixer IF audio and AGC and final audio output LM386 The first step in case of problems is to make sure that the tunable oscillator is working which can be done by listening for its signal on another receiver After the oscillator circuit is confirmed working standard signal tracing procedures should isolate any problem which will be either an incorrectly installed part a defective part or a bad solder connection Correct orientation or polarity of all diodes transistors electrolytic capacitors and ICs is essential PROBLEM Strong shortwave broadcast audible throughout tuning range SOLUTION This can occur if your antenna is too good or if the RF Gain control is turned up too high The high sensitivity of the front end is designed for simple antennas with most reception quite satisfactory with only 25 feet or so of wire PROBLEM Local AM radio station audible throughout tuning range SOLUTION Whether this will even happen depends on how close you are to a local AM station It is very important that all component leads be as short as possible since just a bit of wire can help D1 and the several stages of audio amplification give you a free unwanted classic crystal radio A grounded metal case for the SR2 is one possible solution SR2 23 THE RAMSEY ELECTRONICS CASE KNOB amp HARDWARE OPTION
18. il or IC or whether a RANGE of values is suitable such as 100 to 500 uF Often times common sense will solve a mysterious missing part problem If you re missing five 10K ohm resistors and received five extra 1K resistors you can pretty much be assured that the 1K ohm resistors are actually the missing 10 K parts Hum m m I guess the red band really does look orange Ramsey Electronics project kits are packed with pride in the USA If you believe we packed an incorrect part or omitted a part clearly indicated in your assembly manual as supplied with the basic kit by Ramsey please write or call us with information on the part you need and proof of kit purchase 3 FACTORY REPAIR OF ASSEMBLED KITS To qualify for Ramsey Electronics factory repair kits MUST 1 NOT be assembled with acid core solder or flux 2 NOT be modified in any manner 3 BE returned in fully assembled form not partially assembled 4 BE accompanied by the proper repair fee No repair will be undertaken until we have received the MINIMUM repair fee 1 2 hour labor of 18 00 or authorization to charge it to your credit card account 5 INCLUDE a description of the problem and legible return address DO NOT send a separate letter include all correspondence with the unit Please do not include your own hardware such as non Ramsey cabinets knobs cables external battery packs and the like Ramsey Electronics Inc reserves the right to refuse repair on ANY item in wh
19. inal audio But let s not get ahead of ourselves 22 Install L1 1 H inductor looks like a fat resistor with brown black gold bands 23 Install L2 the other 1 H inductor looks like a fat resistor with brown black gold bands 24 Install C3 001 F disc capacitor marked 001 102 or 1nF 25 Install C2 330 pF disc capacitor marked 330 or 331 26 Install C1 001 F disc capacitor marked 001 102 or 1nF 27 Install R13 1K ohms brown black red R13 isn t part of the RF section but is easier to install now while we re in the area 28 Install R3 1K ohm brown black red Watch that third color band as red is easily confused with orange 29 Install Q1 another of the NPN transistors marked 3904 Observe correct orientation of the flat side when placing this part 30 Install C10 1 F ceramic disc capacitor marked 1 or 104 31 Install R12 1M ohm brown black green C10 and R12 are part of the bias circuit for the audio amplifier U1 Like R13 it is easier to install these parts now 32 Install C30 10pF marked 10 SR2 17 33 Install R2 22K ohms red red orange 34 Install R1 100K ohms brown black yellow 35 Install C24 1 F electrolytic capacitor Remember to watch polarity when installing 36 Install C5 100 pF disc capacitor marked 100 101 or 100K 37 Install C4 01 F disc capacitor marked 01 103 or 10nF 38 Install R26 100 ohms brown black brow
20. listening enjoyment any time of the day Select and install C15 and C16 INITIAL TESTING AND ADJUSTMENT Before turning on your receiver please double check the following correct orientation of all IC s correct orientation of flat side of all transistors correct orientation of the diodes correct polarity of all electrolytic capacitors 1 Connect a speaker or earphones and antenna 2 Install a fresh 9 volt alkaline battery 3 Set both potentiometer controls to their middle positions SR2 21 4 Turn ON the receiver After adjusting the volume to a pleasant level you should hear some shortwave stations by turning the Tune Control no matter how any of the adjustable coils happen to be set While listening to any kind of station whether broadcast or Teletype etc use a small screwdriver to adjust the slugs in transformers T1 and T2 for the best sounding reception The Tuning Control covers varying segments of the bands selected by adjustment of oscillator coil T3 Adjustment of T3 anywhere between the full In position to the full Out position will give the user full range between the minimum and maximum frequency coverage set by C15 and C16 Both T1 and T2 must be adjusted with a non metallic alignment tool such as is used in radio TV service If you do not have one a suitable tool can be made by patiently sanding a screwdriver like blade on the end of a wooden match stick kabob skewer or small plastic crochet needle Again pl
21. mateur 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 SR2 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 19 500 MHz Always something on 24 hours a day Especially strong signals include these among others SR2 5 BBC London an intelligent perspective on world affairs 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 broadcas
22. n 39 Install C23 10 F electrolytic Remember to check the polarity before installing 40 Install Q2 the last 3904 transistor Check the parts placement diagram for correct orientation then install and solder the three leads 41 Install C6 01 F disc capacitor marked 01 103 or 10nF 42 Install R4 22K ohm red red orange 43 Install T1 one of the shielded can inductors marked 42IF 103 44 Install R5 100K ohm brown black yellow 45 Install R6 10K ohm brown black orange 46 Install C28 01 F disc capacitor marked 01 103 or 10nF 47 Install C7 1 F ceramic disc capacitor marked 1 or 104 48 Install R7 1K ohm brown black red 49 Install C31 0039 uF disc capacitor marked 392 or 392K 50 Install R8 10K ohm brown black orange 51 Install C8 01 F disc capacitor marked 01 103 or 10nF 52 Install D1 1N270 glass bead style diode The banded end cathode MUST be oriented as shown on parts layout 53 Install R11 10K ohm brown black orange 54 Install R10 1K ohm brown black red 55 Install R9 1K ohm brown black red 56 Install T2 the other shielded can inductors marked 42IF 103 57 Install L3 12 H inductor looks like a fat resistor with brown red black bands SR2 18 58 Install C9 1 F electrolytic capacitor Check polarity when installing 59 Install C11 10 F electrolytic Observe correct polarity before installing
23. nal we receive the brighter the LED will glow This is great for help pulling in those weak transglobal transmitter signals The gain of the SR2 8 RSSI circuit is controlled by the value the feedback resistor R17 If you are commonly using a small antenna and listening to weak signals increase the value of R17 to customize the response indication of D2 the signal strength LED The final stage and the real secret to the sensitivity of the receiver is the Automatic Gain Control AGC The gain control looks at the amount of signal level present at the output of the demodulator and varies the amount of gain the Amplifier has accordingly If there is a strong signal coming through the demodulator the AGC circuit lowers the gain of the amplifier If the receive signal coming through the demodulator is very weak the AGC circuit increases the gain of the amplifier Q2 allowing us to receive signals from around the world and listen to them with clarity SR2 PARTS LAYOUT DIAGRAM SR2 9 Antenna J1 RF Input amp Filtering M ixer Interm ediate Frequency Filter Am p Interm ediate Frequency Filter Audio Speaker SR 2 Block Diagram Local Oscillator AGC Dem od Signal Strength LED Autom atic Gain Control Receive Signal Strength Indicator C1 C2 C3 L1 L2 Q1 T3 D 3 Q 3 C15 C16 R21 T1 Q2 T2 D1 U 2 J2 U 1 A D2 RSSI U 1 B SR2 10 PARTS LIST CAPACI
24. or some a step toward getting a HAM radio license For others it is a great hobby in itself The SR2 Shortwave Receiver is a good introductory receiver for this hobby After you decide exactly what kinds of listening are of the most interest to SR2 6 you you ll be in a better position to choose a more elaborate receiver While there are various multi band portable radios available you can expect to pay at least 100 for a receiver offering a significant improvement over your trusty SR2 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 SR2 Receiver To learn more about the hobby of HAM radio write ARRL American Radio Relay League 225 Main Street Newington CT 06111 or visit their website http www arrl org CIRCUIT DESCRIPTION The following paragraphs describe the circuit operation of the SR 2 Shortwave Receiver kit Through the use of a simplified block diagram the
25. ore installing T3 the shielded can inductor marked 42IF123 we must make a modification to the part It s time for a little destruction If you SR2 14 SR2 15 SR2 16 jumped ahead and installed T3 we ve got bad news for you Before this shielded transformer can be installed its internal capacitor needs to be removed Looking at the underside of this transformer you ll see a tubular part probably white with a brown band somewhat like the resistors in this kit This is brittle and easily crushed with any sharp object that can be pressed against it with mild force small nail nutpick small screwdriver You ll find this capacitor will easily disintegrate into particles DO NOT crush the capacitors in the other two inductors 21 After crushing the internal capacitor install T3 The part fits in the board only one way Solder all pins That completes assembly of the local oscillator section except for two parts You may notice that we skipped over C15 and C16 while installing the other parts in the area The reason is that you will have to decide the frequency range you re trying to receive to know what value capacitors to install We ll leave that until the end of the assembly process We ll now move on to the RF section of your SR2 kit The next few parts form an input filter and mixer section to combine the RF input with the L O section just built The output of the mixer is the IF from which we ll extract the f
26. our assurance that a team of knowledgeable people have field tested several copies of this kit straight from the Ramsey Inventory If you need help please read through your manual carefully all information required to properly build and test your kit is contained within the pages 1 DEFECTIVE PARTS It s always easy to blame a part for a problem in your kit Before you conclude that a part may be bad thoroughly check your work Today s semiconductors and passive components have reached incredibly high reliability levels and it s sad to say that our human construction skills have not 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 Please send only the defective part s not the entire kit The part s MUST be returned to us in suitable condition for testing Please be aware that testing can usually determine if the part was truly defective or damaged by assembly or usage Don t be afraid of telling us that you blew it we re all human and in most cases replacement parts are very reasonably priced 2 MISSING PARTS Before assuming a part value is incorrect check the parts listing carefully to see if it is a critical value such as a specific co
27. ovide a ground connection 4 If an indoor antenna is necessary simply make it as long as possible and as high up from concrete floors as you can 5 When installing any outdoor antenna BE VERY CAREFUL not to let your antenna wire come in contact with electric power lines 6 Any antenna wire for shortwave listening may run horizontally vertically or some both ways or at an angle 7 If you have a roof mounted TV antenna its feedline will make a great antenna for your SR2 8 Some existing objects such as metal downspouts gutters windows door screens or attic insulation foil can serve as antennas If you are completely restricted to indoor antennas you will enjoy the extra boost of the Ramsey Active Antenna Kit model AA 7 Its built in whip antenna can also be boosted by your simple indoor wire antenna and the AA 7 may be used with any receiver or even a VHF scanner It s easy to build and a nice companion for your SR2 If you need more construction details on antennas check the book mentioned on page 6 or any introductory HAM radio book or the Radio Shack book on Antennas No 62 1083 75 Decide what frequency range you would like to receive and select the values for C15 and C16 from the chart A suggested configuration would be C15 47 pF and C16 100 pF This will give you complete coverage from 6 to 11 MHz by adjusting T3 in or out This is a very active section of the Shortwave Band and will provide you with hours of
28. r dotted end as shown in the parts layout diagram and on the PC board silkscreen Solder all 8 pins 69 Install C14 220 F electrolytic capacitor The positive lead of the capacitor must be placed in the hole next to the sign In the same way 70 Install C13 placing the positive lead in the correct PC board hole Remember the banded side indicates the negative lead 71 Install the 9 volt battery snap connector making sure that the red black leads are inserted correctly SR2 19 72 Install the battery clamp Position battery and holder so as not to cover nearby PC board mounting holes Use the method for securing the clamp that is most convenient for you such as wire looped through clamp and PC board holes soldered small screws double faced adhesive strips hot melt glue 73 If you desire increased audio output C27 10 F may be installed Be sure the and leads are inserted correctly 74 We re at the end now just one part left to install Install D2 the red LED signal indicator The short lead is the cathode it goes toward potentiometer R21 Leave it standing about 1 2 an inch off of the board when soldering After soldering bend it over to a 90 angle at its midpoint so that it faces the outside of the board Your shortwave broadcast receiver is now finished except for the capacitors that will determine the frequency range you will receive SHORTWAVE ANTENNA IDEA
29. rt looks like a transistor except that it only has two leads It must be installed with the proper polarity to work correctly You will note that it has a flat side Be sure to look at the PC board silkscreen or parts layout diagram for proper placement of the flat side Once you have correctly placed the part solder the leads 7 Install R23 10K ohm brown black orange 8 Install Q3 an NPN transistor marked 2N3904 This part is also oriented by the flat side so check your parts layout diagram for proper placement Bend the center lead out until it fits in the board and seat the part as close to the PC board as possible Solder all three leads 9 Install C17 a 100 pF capacitor marked 100 101 or 100K 10 Install C25 001 F disc capacitor marked 001 102 or 1nF 11 Install C19 a 1 F ceramic disc capacitor marked 1 or 104 12 Install C18 another 1 F ceramic disc capacitor marked 1 or 104 13 Install R20 100K ohms brown black yellow 14 Install R25 a 270 ohm resistor red violet brown 15 Install R19 10K ohms brown black orange 16 Install R24 1K ohms brown black red 17 Install C26 the 1000 F electrolytic capacitor Remember to check the polarity and install properly before soldering 18 Install R22 270 ohms red violet brown 19 Install C20 001 F disc capacitor marked 001 102 or 1nF 20 Install C21 another 001 F disc capacitor marked 001 102 or 1nF Bef
30. ts 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 SR2 Our companion receivers designed for the HAM bands will let you tune into these SSB and CW broadcasts SHORTWAVE LISTENING AS A HOBBY 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 f
31. verter RAMSEY HOBBY KITS SG7 Personal Speed Radar SS70A Speech Scrambler TT1 Telephone Recorder SP1 Speakerphone MD3 Microwave Motion Detector PH10 Peak hold Meter LC1 Inductance Capacitance Meter RAMSEY AMATEUR RADIO KITS DDF1 DopplerDirection Finder HR Series HF All Mode Receivers QRP Series HF CW Transmitters CPO3 Code Practice Oscillator VLF1 Low Bander Low Frequency SWL Converter 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 19 5MHz SHORTWAVE RADIO INSTRUCTION MANUAL Ramsey Electronics publication No MSR2 Revision 1 4 First printing January 2001 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 Printed in the United States of America SR2 3 4 19 5MHz SHORTWAVE RADIO Ramsey Publication No MSR2 Manual Price Only 5 00 TABLE OF CONTENTS Introduction to the SR2 4 What You Can Expect to Hear 4 Shortwave Listening as a Hobby 5 Circuit Description 6 Parts Layout Diagram
Download Pdf Manuals
Related Search