Ramsey Electronics HR40 Stereo Receiver User Manual
Contents
1. Antenna and suitable cable OPTIONAL Ramsey Electronics Case and Knob Kit Model CHR or Your own choice of enclosure and hardware HR40 8 LEARN AS YOU BUILD ASSEMBLY STRATEGY To help you learn just what exactly is going on we ll discuss the purpose of most of the components or groups of components as we go along Since we are trying to keep assembly of the board simple we will not be able to fully describe each individual component s function as you build but Ramsey s Learn As You Build kit assembly philosophy still stands Check off each step as understood and completed Examine the schematic diagram and PC board X ray illustration as you proceed In all steps install means to insert into the correct PC board holes solder properly and trim all excess component leads Use good soldering skills let your soldering iron heat each connection wire so that the wire itself and the foil trace both become hot enough together to melt the applied solder so that it flows smoothly around the wire lead and on to the PC board trace Mount all electrical parts on the top side of the board provided This is the side that has no traces or pads on it When parts are installed they are 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 The part is then soldered securely to the board and the remaining lead length is then clipped off The clipped off leads should2. as specified and that the ONLY reason any HR receiver will not work after the 1 2 hours needed for assembly is if we packed the wrong parts or you put them in wrong Once you are sure the receiver performs as specified there is a lot you can do to coax maximum performance from the basic circuit For instance if you choose a DC power source other than the 9 volt battery the space allowed for the battery offers plenty of room for a top mounted perfboard or PC board for preamp stages and or any sort of passive or active audio filter that suits your needs Keep your work neat with short leads so as not to introduce broadcast station overload ALTERNATE POWER SOURCES Most of the HR40 circuitry can be operated from 6 to 14 volts without damage or significant modification However it is quite important that you carefully hook up with the correct polarity reverse polarity or excessive voltages WILL damage your kit BANDSPREAD AND TUNING RANGE The easiest way to enjoy finer tuning if you plan to use your receiver only for checking your favorite segment of the band is to adjust the oscillator coil so that your desired segment falls within the second half of the rotation range of the tuning control The first half of the rotation range covers about 70 of the actual tuning in KHz while the other 30 is spread over the other half of the rotation range If your interest is in monitoring SSB the normal alignment will work fine For optimum CW o
3. 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 coil or IC or whether a RANGE of values is suitable such as 100 to 500 F 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 HR40 27 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
4. be saved for later use as jumper wires As you can see in examining the circuit board and parts there are many tall components such as the potentiometer capacitors and switches along with a lot of small parts First you will install the larger components so they can be used as markers So that you don t spend extra time troubleshooting we strongly recommend that you follow the assembly strategy and step by step procedures we have provided HR40 9 HR40 10 PARTS LAYOUT HR40 11 RECEIVER ASSEMBLY 1 Install the RCA antenna jack J1 Solder all four points 2 Install C5 a 01 F ceramic disc signal coupling capacitor This capacitor brings the signal up to the front of the PC board Notice the long PC trace from J1 through C5 to R1 3 Install potentiometer R1 the RF gain control Insert it into the PC board so that it seats firmly and is straight and even Solder the three pins and the two mounting tabs 4 Install L1 marked 421F 123 which tunes or preselects the signal input from the antenna through C5 and R1 5 Install U1 the SA602 IC mixer oscillator The marked end of the IC band or dot must face the FRONT of the PC board If you wish install an 8 pin DIP socket still remembering to orient and install the SA602 correctly Please don t be afraid to solder U1 directly to the board as we have seen more repair problems with DIP sockets than from direct soldering of IC chips The parts that we have put in
5. frequency change of several KHz when connecting or disconnecting the counter Also this additional capacitance in the oscillator circuit reduces the tuning range to approximately 100 KHz thus offering another way of getting bandspread for your favorite frequencies Finally it may be necessary to operate the counter on battery power only connection of an AC adapter might introduce considerable hum into the receiver THE LM386 AUDIO OUTPUT As already mentioned the LM386 is certainly capable of far more audio power output than is given in this basic receiver circuit It can only boost what it gets directly from the SA602 There is certainly space on the HR40 circuit board to install an audio preamplifier i e 2N3904 or minimum gain LM386 in the circuit trace between C8 the audiocoupling capacitor from pin 4 of the SA602 to the volume control The following is an audio preamplifier idea submitted by one of our customers Ramsey Electronics in no way warrants that this modification will achieve any particular ideal signal to noise ratio or audio HR40 23 frequency response but is does significantly boost the output of the SA602 reaching the LM386 audio amplifier IC Instead of the traditional transistor audio preamp circuit an additional LM386 is used in its minimum gain configuration gain of 40 plus one electrolytic capacitor 1 to 10 uF to achieve minimum parts and PC board drilling This use of two LM386 ICs amplifies the audio si
6. hot or warm Slowly rotate the tuning control At this point you may or may not hear anything since neither coil has been adjusted If you do hear a few whistles as you tune the SA602 oscillator is working just fine These simple initial checks verify that your receiver is operating well enough to proceed to the next section alignment HR40 15 Alignment Turn on whatever reference signal source you plan to use This can be a regular transceiver keying a few milliwatts into a dummy load a crystal oscillator or a signal generator Or you can look for a known signal that you have tuned in on another receiver If you are without any reference signal whatsoever but have a reasonable antenna you can use your familiarity with the 40 meter band to make a rough alignment of the receiver If Ham radio and 40 meters are new to you here s a rough idea of what you can expect to hear on this busy band 7 00 7 08 MHz CW most of it is fairly fast 7 08 7 15 MHz Teletype RTTY and digital operation 7 10 7 20 MHz SSB voice many different languages 7 20 7 35 MHz general SSB voice operation NOTE A miniature transformer alignment tool is used to turn the slugs in L1 and L2 If you do not have one make one by gently sanding the tip of a wooden match stick a kabob skewer or other piece of wood or plastic While it seems that a small jeweler s screwdriver could be used be aware that its metallic construction will make adjustm
7. 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 which 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 HR40 28 HR40 AMATEUR RECEIVER KIT Quick Reference Page Guide Introduction to the HR
8. so far bring the signal from the antenna jack up to the RF Gain control actually the RF attenuator and to a tuned circuit composed of L1 and its internal capacitor Inductor L1 allows us to match and tune the 40 meter band signals to the SA602 s input 6 Install C6 01 F marked 103 01 10nF This capacitor bypasses pin 2 of the SA602 to ground Bypass means to provide a nice low impedance impedance means AC resistance path to ground 7 Install R4 270 ohms red violet brown which drops the 9 volt battery supply to 6 7 volts safe for the SA602 8 Install D2 6 2 volt Zener diode This is the smaller of the two diodes and has a painted glass body This diode acts as a voltage regulator by keeping the voltage across it constant 9 Install C10 a 100 220 F electrolytic capacitor Electrolytic capacitors are marked by polarity and must be installed in the proper direction You ll see that one side of the capacitor has a black band and is marked with a sign this is the negative side the other side is the positive lead Make sure you insert the positive lead into the marked hole on the PC board 10 Install C11 a 100 220 F electrolytic capacitor Remember to observe correct polarity C10 and C11 provide voltage stabilizing which directly improves the performance of the SA602 oscillator 11 Install C2 100pF ceramic disc capacitor marked 100 or 101 This HR40 12 capacitor is a first step in setti
9. the mixer oscillator stages Advantages of any Direct Conversion receiver include It is simple and therefore economical and easy to build It is quite sensitive even with a simple antenna Its tuning oscillator could even be set up to serve directly as a transmitter VFO in a simple transceiver setup A common problem with DC receivers is that they are easily overwhelmed by strong AM broadcast stations from almost anywhere whether it s your local rock and roll broadcaster Radio Moscow or the Voice of America Even popular classics like Heath Kit s HW 8 QRP transceiver exhibit this characteristic to a frustrating degree Another problem with DC receivers is HR40 6 called microphonics which is a phenomenon where almost anything in the physical circuitry of the receiver can act as a sort of microphone or audio sound pickup Touch or bump such radios and you will hear a thump or ring in the speaker or earphones Still another problem is that of AC line hum whenever an unregulated power supply is used rather than batteries The Ramsey HR40 s use of the SA602 integrated circuit chip offers a circuit configuration that is as immune as any simple superhetrodyne to the classic problems with Direct Conversion receivers The receiver is not as easily overloaded by the VOA or Radio Moscow broadcasts and there are few annoying microphonics or incurable AC hum Circuit Description U1 combines a double balanced ac
10. 40 4 Circuit description 6 Parts list 7 Schematic diagram 9 Parts layout 10 Assembly instructions 11 Initial testing 14 Alignment 15 Troubleshooting guide 19 Warranty 26 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 Price 5 00 Ramsey Publication No MHR40 Assembly and Instruction manual for RAMSEY MODEL NO HR40 AMATEUR RECEIVER KIT RAMSEY ELECTRONICS INC 590 Fishers Station Drive Victor New York 14564 Phone 585 924 4560 Fax 585 924 4555 www ramseykits com TOTAL SOLDER POINTS 84 ESTIMATED ASSEMBLY TIME Beginner 3 0 hrs Intermediate 2 0 hrs Advanced 1 0 hr
11. CPO3 Code Practice Oscillator 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 HR40 AMATEUR RECEIVER KIT INSTRUCTION MANUAL Ramsey Electronics publication No MHR40 Revision C1 First printing January 1995 COPYRIGHT 1994 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 HR40 3 HR40 AMATEUR RECEIVER KIT Ramsey Publication No MHR40 Price 5 00 TABLE OF CONTENTS Introduction to the HR40 4 About Direct Conversion 5 Circuit description 6 Parts list 7 Schematic diagram 9 Parts layout 10 Assembly instructions 11 Initial testing 14 Alignment 15 Using your HR40 16 Troubleshooting guide 19 Notes for experienced users 20 Warranty 26 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR RAMSEY ELECTRONICS INC 590 Fishers Stat
12. HR40 1 40 METER 7 0 MHZ ALL MODE RECEIVER KIT Ramsey Electronics Model No HR40 Small in size but BIG in features Easily tunes SSB CW RTTY and AM Smooth varactor tuning of any desired 250KHz segment of the 40 meter band easily retuned Uses the popular SA602 IC chip for outstanding sensitivity and efficient operation Front panel RF Gain Tuning and Volume controls Efficient LM 386 Audio amplifier drives speaker or earphones with a clean crisp audio Informative manual answers questions on receivers hookups and uses enhances resale value too Ideal companion to the Ramsey QRP 40 CW Transmitter Runs on a standard 9 volt battery Clear concise assembly instructions lead you to a finished product that works FIRST time HR40 2 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 HR Series HF All Mode Receivers QRP Series HF CW Transmitters CW7 CW Keyer
13. ameter speaker lying naked on your workbench will give you a fair test of the speaker output capability Speaker quality and well designed enclosures have their clear purposes A reasonable speaker in a box delivers a pleasant listening volume On the other hand the LM386 indeed can deliver more audio output punch than is developed in our HR series kits For example our FM receivers using the same LM386 audio IC deliver more volume These receivers however take advantage of IF amplifiers drift compensation and crystal controlled oscillators built into mass production sophisticated FM receiver ICs A heavier drain on the HR40 s battery by stronger audio will quickly result in chirpy signals and oscillator drift as well as the need for frequent battery replacement Remember the SA602 circuits similar to Ramsey s generally call for sets of C or D cell batteries For Experienced Builders more information regarding audio output is in the general notes The simple design of the audio stage of the Ramsey HR40 receiver assumes preference for headphone or small speaker operation low battery drain and general economy MORE AUDIO POWER ANOTHER WAY If you want to use your HR40 for casual band monitoring while you are busy across the room in the shop or to share with a class or club and want LOTS more volume try building up our very inexpensive Ramsey BN 9 2 watt general purpose amplifier kit Supply DC voltage to such an amplifier s
14. d Technician privileges The manuals for the 30 and 20 meter versions assume the general Ham radio know how that should accompany a General Class or higher license ABOUT DIRECT CONVERSION RECEIVERS The HR40 is a Direct Conversion receiving circuit There is no need for IF intermediate frequency circuitry The receiver processes the incoming signal right at its own frequency with no need to mix or transform it with additional internal oscillators and amplifiers running at intermediate frequencies such as 455 KHz The advantage of this type of receiver is that it permits tuning of CW AM and SSB signals with no need for a separate BFO A BFO or beat frequency signal oscillator is an entirely separate oscillator circuit used in the IF intermediate frequency section of a superhetrodyne receiving circuit Since this frequency is designed specifically for SSB and CW you will also hear the carrier signal of any AM shortwave broadcast station The most elementary DC receiver consists of just an oscillator and an antenna connected to the inputs of a Product Detector whose tiny audio output is then amplified for listening A product detector can be made from simple diodes or a pair of transistors or a dual gate FET transistor or various IC s The Ramsey HR40 efficiently utilizes the Signetics SA602 IC for both the tunable oscillator and the product detector circuits giving the equivalent of seven transistors in
15. ent of L2 very erratic and could damage the powdered iron slug Any kind of metal tip will affect the coils true value so that the oscillator will run at one frequency with the metal instrument in the coil can and a completely different frequency by itself For now set the tuning control to its mid point Use the insulated alignment tool to gently rotate the slug in the top of L2 If it starts to get tight DO NOT FORCE IT Instead gently rock it back and forth until it loosens up You should find your 7MHz reference over a range of approximately 6 to 9MHz The varactor tuning control can cover any 300KHz range chosen within the 6 to 9MHz limits Adjust L1 for maximum received signal strength Now you re ready to receive on the air signals After you get used to its tuning and performance you can adjust the tuning control L1 and L2 to get the exact tuning range you want ALIGNMENT HINT FOR ALL DIRECT CONVERSION RECEIVERS You will clearly hear the oscillator of your kit very close to its receiving frequency if you tune around for it on ANY shortwave radio covering the same frequency range Even if your shortwave set does not have a BFO beat frequency oscillator for CW SSB you ll still hear a powerful hiss or quieting when your shortwave receiver is tuned near the frequency of the HR40 Your shortwave receiver is actually picking up the oscillator signal within the HR40 HR40 16 USING YOUR RECEIVER In your first t
16. eparately using D cells a lantern or auto battery or a well filtered power supply ADDING AN LED POWER ON INDICATOR For many people a pilot lamp to indicate power on is more than a nice touch They expect it and depend on it reminding us that real radios glow in the dark Adding a simple LED power on indicator to your Ramsey HR40 is easy All you need is the LED itself and a small 1K or 2 2K resistor Study the PC traces between the positive battery supply wire and the on off switch The unused connectors on top of your switch are an ideal point to get the DC voltage needed for the anode longer lead of the LED Plan where and how HR40 18 you wish to install the LED in your enclosure Locating the LED immediately above the on off switch is ideal The simplest way to make a neat installation is to drill a hole just sightly smaller than the diameter of the LED Then enlarge the hole a little bit at a time just enough to let the LED be pressed in and held firmly The resistor may be connected to either the anode or cathode side of the LED but the anode must be connect to the DC with the cathode connected to the nearest common ground If you are wondering why we did not include these pennies worth of parts with your kit you can believe any of the following reasons 1 We wanted to stretch your battery budget and the current draw on the LED is about 6mA How long will your battery last if you leave your receive
17. er Kits share the same basic PC boards and most components which are not frequency critical However there are enough differences among the band characteristics desirable operating features for each band and differences among the people who would most typically choose a particular band that a separate instruction manual is published for each receiver Other circuit details which vary from band to band include the tuning range provided by the varactor circuit Bandspread for favorite band segments is easy on 160 or 80 meters but requires other considerations on higher frequencies Also some bands appeal to QRP operators more than others and some are better suited for portable and travel use Therefore we are pleased to assure you that your manual for the HR40 receiver and the receiver circuit itself has been designed with an understanding of typical operating needs and expectations for the 40 meter band HR40 5 This receiver circuit is ideal for discovering just how simple a true Communications Receiver can be That s right there is a BIG difference between the Ramsey HR40 and other simple short wave radio circuits we can try to build Yet it is very easy to build Our HR series are by far the easiest to build of all the Ramsey kit receivers and therefore very nice for radio newcomers Consequently our manuals for the 40 and 80 meter receivers are written with beginners in mind since both of these bands offer Novice an
18. ests you might feel that tuning in CW and SSB stations by turning the control shaft seems tricky Don t despair The addition of a simple knob to the final version of your kit will result in more comfortable tuning right away Also the larger the knob the easier the tuning is Even smoother control can be accomplished by a vernier dial which will also provide calibration marks Finally if you intend to use this receiver only for monitoring or working a very specific frequency range you can add a resistor in series with the tuning control to achieve the bandspread you want for your own application For details please see the upcoming section Notes to Experienced QRP Builders We want you to enjoy this economical receiver whether you use it for portable listening or as a base for easy experimentation Isn t it amazing the performance that can be achieved with just two IC chips TUNING SSB SIGNALS As you know the protocol for the 160 80 40 Meter Bands is lower sideband LSB with Upper Sideband USB used for 40 18 15 12 10 Meter SSB To check or scan a given band for SSB signals tune your HR40 up from the low end for USB signals and down from the high end for LSB CW OPERATION A direct conversion receiver lets you hear equal sidebands on either side of the zero beat null of the exact frequency of the signal to which you are listening Therefore when adjusting the frequency of your companion Ra
19. gnal of the SA602 by a factor of 1000 This modification requires cutting the circuit trace leading from C8 to the volume control R3 Additional LM386 used as AF preamplifier between U1 and U2 Pins 1 7 8 not used Pins 2 4 to ground Pin 3 to side of c 2 2 pF Pin 5 to side of new 1 to 10 uF capacitor Pin 6 to DC supply board trace The side of the new capacitor is connected to the circuit trace leading to the volume control Mount this capacitor as close to the body of the new LM386 as possible Keep all leads as short as possible This modification results in very good speaker volume but will also require closer attention to battery quality and condition or else the audio circuits will cause oscillator instability Two alkaline cells in parallel or a 12 volt supply are recommended If the gain is too much use a resistor to reduce the voltage supplied to pin 6 of preamp LM386 Finally we remind you again that modification of any PC board puts you on your own voiding your factory warranty making your unit ineligible for factory repair Make sure the receiver is working properly and that you understand how to use and repair it BEFORE making any changes in the original design Enjoy it 1 MEGOH M NE60 2 PIN 7 COUNT ER TO 27 pF HR40 24 CONSTRUCTION NOTES HR40 25 HR40 26 The Ramsey Kit Warranty Please read carefully BEFORE calling or writing in about your ki
20. he tuning dial knob Then as you tune in different frequencies pencil in on the paper the received frequency Or a simple logging scale may be affixed behind the tuning knob on the front panel A logging scale is simply a set of numbers for adjusting a control For example 4 might represent 7 1MHz and 5 5 being 7 12MHz and so forth DIRECT FREQUENCY READOUT A novel advantage of the simple direct conversion receiver is that a general purpose frequency counter may be used to give a direct readout of the oscillator frequency While you could experiment with an RF pickup loop or tuned circuit and counter preamplifier to boost the oscillator s tiny output to a level suitable for the counter the most reliable method is to wire a high impedance counter probe line directly to pin 7 of the SA602 terminated to a rear panel frequency counter connection of your choice This will consist of a short piece of mini coax to a 1 megohm resistor bridged by a 27 to 33pF capacitor as shown below With the RF gain turned all the way up it may be possible to hear the counter s busy humming action in the background but not to a serious degree It drops out with a slight reduction of the RF gain If you decided to add such a counter connection to your receiver remember that the coax as well as the coupling capacitor become part of the oscillator circuit Make the coaxial cable connecting the counter to the receiver as short as possible You will experience a
21. ion Drive Victor New York 14564 Phone 585 924 4560 Fax 585 924 4555 HR40 4 INTRODUCTION Our HR40 and HR80 models are thought of as best for beginners because Hams with a Novice or Technician licenses can operate CW in the 80 and 40 meter bands If you like plenty of action and DX long distance communications the 40 meter Ham band is the place to be Almost 24 hours a day there s something interesting happening on 40 meters These are several groups of people who will enjoy this Ramsey HR40 Receiver Experienced Ham operators who want a simple extra receiver for keeping one ear on 40 meters while doing something else Beginners who would like to start by listening in on one of Ham radios most active bands QRP builders who want a quick easy and reliable SA602 board kit for 40 meter projects QRP builders not interested in our warranty or following our step by step assembly and use directions but who want to get their hands on our most versatile receiver PC board and parts kit for their own projects The Ramsey HR40 has something fun and easy for each of them Note To Beginners Building the HR40 is really no harder than any of our other receivers in this series Just follow the directions carefully All you need to know to successfully complete this receiver is contained in this detailed manual Enjoy your HR40 receiver RAMSEY HR SERIES AMATEUR RECEIVERS All Ramsey Direct Conversion Receiv
22. msey QRP transmitter be certain that you have in fact tuned to the other station s lower sideband The two stations will actually be several KHz apart Because this receiver s oscillator is not shared with a transmitter as in transceivers there is no need for separate RIT receiver incremental tuning ON THE AIR TRANS RECEIVING Let s assume that you plan to use this receiver together with a Ramsey QRP transmitter which provides an RF protected receiver antenna jack While the receiver will be protected from RF damage from the transmitter do not expect to monitor your own signal on this receiver while transmitting unless you are a QRP design expert and do not care about future factory service from Ramsey Even with the circuit protection the RF signal is just too much for the SA602 The transmitter signal overpowers the SA602 disrupting the internal oscillator However the receiver can handle the output of a crystal oscillator or VFO for frequency spotting purposes HR40 17 A better operating arrangement will consist of a T R switch either a manual switch or break in delay relay circuit This switching circuit can disconnect the SA602 audio output at the volume control and switch in a pleasant oscillator pitch keying sidetone which is amplified to listening level by LM386 The Ramsey Electronics Universal timer kit No UT 5 is easily adapted as a sidetone oscillator SPEAKER OPERATION A fifty cent two inch di
23. ng up the resonant frequency of the SA602 s internal oscillator using the resonant LC circuit to be created along with C1 C3 and L1 12 Install C1 100pF disc capacitor marked 100 or 101K 13 Install C3 001 F disc capacitor marked 102 or 001 or 1nF 14 Install L2 shielded oscillator coil marked K6883 or K6886 15 Install C4 100pFdisc capacitor marked 100 or 101 C4 adds variable capacitance of the varactor tuning network to the oscillator circuit already formed by L2 C1 C2 and the SA602 16 Install D1 the 1N4002 diode making sure that the cathode or banded end is oriented towards the back of the PC board This diode performs the function of a varactor diode A varactor diode acts like a variable capacitor whose capacitance is controlled by the voltage across it There is nothing fancy about the varactor diodes so we are using a common rectifier diode as a varactor 17 Install R5 10k ohms brown black orange 18 Install R2 10k potentiometer tuning control 19 Install R3 10k potentiometer volume control This control varies the level of audio from pin 4 of the SA602 to the LM386 audio amplifier 20 Using a scrap piece of wire snipped from an installed component install JMP 1 Jumpers are required sometimes in PC board layout to make a connection that has to cross over other PC board traces This particular jumper brings 9 volts from the power switch to the long circuit trace supplying voltage to the en
24. nly listening set the lower band edge with the tuning control in the 12 00 position of its range HR40 21 In planning any bandspread improvement it is useful to understand exactly how varactor tuning works The control level varies the amount of DC voltage applied to the diode The highest produces the lowest capacitance while the lowest voltage yields the highest capacitance The spread is typically about 30 to 40pF from minimum to maximum The goal in achieving bandspread or finetuning is to achieve a smaller variation in capacitance with the comfortable tuning of a knob Any resistor in a range from 500 ohms to 3000 ohms connected in series with the ground lead of R2 will set a limiting effect on varactor capacitance range and therefore create a bandspread effect The higher the resistance value the shorter the available tuning range If you wish to reduce the tuning range of R2 down to 40 or 30KHz or even less for a favorite band segment or calling frequency reducing the value of C4 will decrease the capacitance effect of the varactor diode D1 Values from 2 to 5pF may give you exactly the tuning range you are looking for If you are using your own enclosure and have room for a separate fine tuning control one useful choice is a 250 ohm speaker attenuation rheostat Radio Shack model no 271 265 wired in series with either outside leg of the main tuning control Such a control can make fine adjustments
25. r on for a few days just like we leave our computers and ham gear on all the time 2 We thought you d have more fun planning and installing your own lamp that glows in the dark HR40 19 TROUBLESHOOTING TIPS PROBLEM ALL signals are chirpy and unstable SOLUTION Sorry to have to say it but this condition is only caused by a weak battery Use a fresh alkaline cell Any strong signal forces the audio circuit to rob voltage from the oscillator which causes the instability PROBLEM Occasionally good but erratic operation SOLUTION Check very carefully for a poor solder connection PROBLEM Signals have an unpleasant hissing pitch SOLUTION Try a different set of headphones different speaker or external audio amplifier Some cheap headphones designed for casual music listening have an undesirable filtering effect on CW signals PROBLEM Oscillator inoperative or wrong frequency SOLUTION In addition to checking solder joints be sure that L1 is oriented correctly and that C1 C2 C3 and C4 are installed in correct positions PROBLEM Loud AC hum or buzz SOLUTION If you are using the receiver with a battery or simply for listening i e not connected to a transmitter or a AC power adapter these are likely causes of the AC hum No ground connection Receiver located too close to an AC device such as an older electric clock AC powered radio etc Antenna very close to a power cord or house wiring If
26. t 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 your 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
27. ter to find errors now before you test the HR40 and it s easier on the ego too HR40 14 INITIAL TESTING OF YOUR HR40 You re now ready to power up and test your HR40 but before you begin take some time to sweep off your bench of any loose component leads or solder splashes A clean work area not only makes testing less frustrating but also less prone to problems REQUIRED FOR INITIAL TESTING AND ALIGNMENT A known frequency standard in the 10MHz range such as Crystal oscillator or RF signal generator or Grid Dip oscillator or QRP transmitter such as a Ramsey QRP 40 A Ramsey frequency counter CT 90 etc or Any accurately calibrated receiver covering 40 meters At the least personal familiarity with the 40 Meter Ham band And the following Coil alignment tool can be homemade per directions and 9 volt battery antenna earphones or a small speaker Connect the following Fresh 9 volt battery Earphone or speaker Antenna or at least a random length of wire Adjust the three controls to the middle of their ranges Press the power switch on You should hear background noise immediately at least a gentle hiss See if the volume control does its job vary it and notice how the volume changes See if the RF gain control has some effect on what you hear If everything seems ok so far feel the tops of the two IC s with your finger Neither should feel
28. tire circuit Notice how the jumper crosses over the other traces leading from the volume control 21 Install S1 the power switch 22 Install the 9 volt battery snap connector making sure that the red and black leads are correctly installed 23 Install C7 01 F disc capacitor marked 103 or 01 or 10nF 24 Install C8 a small 4 7 10 F electrolytic capacitor Observe correct polarity 25 Install R6 10K ohm resistor brown black orange 26 nstall U2 the LM386 audio amplifier IC chip Just like the SA602 you must correctly position the notched or banded end 27 Install C12 100 220 F electrolytic capacitor observe polarity This capacitor couples the output of the LM 386 to the speaker jack 28 Install C9 4 7 10 F electrolytic capacitor observe polarity HR40 13 29 Install speaker jack J2 This jack is a 2 5mm type and mates with any 2 5mm plug as found on virtually all mini earphones 30 Install the 9 volt battery clamp Use a scrap component lead to loop through the two holes in the clamp and through the PC board Solder the leads firmly to the board and to the battery clamp Do not use too much solder on the clamp as this will cause the battery to sit too high and not seat securely Congratulations You have completed the assembly of your HR40 receiver kit Now is a good time to sit back and admire your work and make a final check of all solder joints and component placement It is always bet
29. tive mixer and oscillator in a single 8 pin IC chip L1 peaks the RF input to pins 1 and 2 of U1 L2 with varactor diode D1 and R2 C1 C2 and C4 control the resonant frequency of U1 s internal oscillator Rotating R2 gives about a 250 KHz tuning range The audio output is fed from pins 4 and 5 through R3 volume control directly to the LM 386 audio amplifier R1 controls RF gain C9 boosts the gain figure of the LM 386 from 20 to 50 HR40 7 PARTS SUPPLIED WITH THE HR40 KIT CAPACITORS 1 001 F disc capacitor marked 102 001 or 1nF C3 3 100pF disc capacitor marked 100 or 101K C1 C2 C4 3 01 F disc capacitor marked 103 01 or 10nF C5 C6 C7 2 4 7 to 10 F electrolytic capacitor C8 C9 3 100 220 F electrolytic capacitor C10 C11 C12 RESISTORS 3 10K ohm potentiometers R1 R2 R3 1 270 ohm resistor red violet brown R4 2 10K resistors brown black orange R5 R6 INDUCTORS 1 Shielded Coil K6883 or K6886 L2 1 Antenna input transformer marked 421F 123 L1 SEMICONDUCTORS 1 1N4002 Diode black epoxy style D1 1 SA602 IC U1 1 LM386 IC U2 1 6 2 volt Zener Diode small glass body D2 HARDWARE AND MISC 1 Drilled printed circuit board 1 9 volt battery hold down bracket 1 9 volt battery connector 1 RCA style jack antenna connector J1 1 subminiature earphone jack J2 1 PC mount pushbutton switch S1 REQUIRED NOT SUPPLIED 9 volt battery alkaline or heavy duty type Earphone or small speaker
30. to a CW signal so the tone is pleasant and smooth sounding If you want the opposite of bandspread that is as MUCH frequency range as possible over full rotation of the tuning knob increase the value of C4 This will cause the varactor diode to have greater effect on the tuning Try values of 33pF up to 100pF FREQUENCY STABILITY A kilohertz of drift is not a big deal in FM circuits or a shortwave broadcast configuration but ANY frequency instability is annoying when trying to receive CW or SSB The varactor controlled Local Oscillator is indeed a VFO and therefore needs all the consideration given to any VFO circuit Even though this tunable oscillator design takes good advantage of the SA602 s capabilities and offers nice tuning range from a simple varactor circuit we do not represent it as suitable for transmitter frequency control or for demanding receiver applications In any ham VFO design ANY unshielded or uncompensated oscillator components are susceptible to the influences of temperature change and of nearby moving objects The use of a suitable enclosure and secure mounting of the PC board within that enclosure will maximize the stability of the oscillator One to two KHz of slow drift may be expected as components warm to operating temperature after that the oscillator is reasonably stable HR40 22 OTHER METHODS OF DIAL CALIBRATION A easy way of making your own dial is to paste a small rectangle of paper behind t
31. your receiver is being used with a transmitter the transmitter power supply may be the source of the unwanted AC hum If you are using a 9 volt AC power adapter the adapter design may not be of sufficient quality for this application Try a bypass capacitor or a different adapter or a well designed and filtered DC power supply A careful check of all construction WILL solve your problem Over 95 of the kits returned for repair have nothing more than a simple assembly or construction error HR40 20 GENERAL NOTES FOR EXPERIENCED QRP BUILDERS We at Ramsey Electronics deliberately designed the HR series of DC receivers to be easily available affordable and buildable by any person willing to follow the assembly directions To achieve this goal the current models with direct coupling of the SA602 to the LM386 operating with a gain figure of 50 use an amazing minimum of parts If you know what you are doing with DC receiver design we encourage you to use our HR series for reliable building blocks for achieving maximum performance for you own application If a good idea does not work as expected you can easily restore your Ramsey receiver to its original circuit configuration Our job has been to keep in stock for immediate delivery a good basic design a quality PC board with plenty of work room useful front panel controls correct and adjustable inductors workable varactor tuning and the popular SA602 We know these receivers WORK
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