Ramsey_HR-20_user.pdf

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1、 20 METER (14 MHZ) ALL MODE RECEIVER KIT Ramsey Electronics Model No. HR20 Heres the ideal mini-receiver for catching all the busy action on 20 meters from your office, home or on trips! Small in size but BIG in features: Easily tunes SSB, CW, RTTY and AM Smooth varactor tuning of any desired 250KHz

2、 segment of the 20 meter band, easily retuned 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 th

3、e Ramsey QRP20 CW Transmitter Runs on a standard 9-volt battery Clear, concise assembly instructions lead you to a finished product that works FIRST time! Add our case and knob set for a finished Pro look. Cases match all Ramsey products. HR20 2 PARTIAL LIST OF AVAILABLE KITS RAMSEY TRANSMITTER KITS

4、 FM10A, FM25B Stereo Transmitters AM1, AM25 AM Transmitters TV6 Television Transmitter FM100B Professional FM Stereo 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

5、Speed Radar SS70A Speech Scrambler MX5, MX-10 Mixers MD3 Microwave Motion Detector TFM3 Tri-Field Meter STC1 Stereo Transmitter Companion RAMSEY AMATEUR RADIO KITS HR Series HF All Mode Receivers QRP Series HF CW Transmitters DDF1 Doppler Direction Finder CPO3 Code Practice Oscillator QRP Power Ampl

6、ifiers 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. HR20 AMATEUR RECEIVER KIT INSTRUCTION MANUAL Ramsey Electronics publication No. MHR20 Revision C1 First printing: Janu

7、ary 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. HR20 3 HR20 AMATE

8、UR RECEIVER KIT Ramsey Publication No. MHR20 Price $5.00 TABLE OF CONTENTS Introduction to the HR20 .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 HR20 .16 Troubleshooting

9、 guide .19 Notes for experienced users .20 Warranty .26 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR HR20 4 INTRODUCTION: If you like plenty of action and DX (long distance) communications, the 20 meter Ham band is the place to be. Almost 24 hours a day theres something interesting happening on 20 meters

10、. There are several groups of people who will enjoy this Ramsey HR20 Receiver: Experienced Ham operators who want a simple extra receiver for keeping one ear on 20 meters while doing something else. Beginners who would like to start by listening in on one of Ham radios most active bands. QRP builder

11、s who want a quick, easy and reliable SA602 board kit for 20 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

12、 HR20 has something fun and easy for each of them. Note To Beginners: Building the HR20 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 yo

13、ur HR20 receiver. RAMSEY HR-SERIES AMATEUR RECEIVERS: All Ramsey Direct Conversion receiver 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

14、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

15、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 HR20 receiver and the receiver circuit

16、 itself have been designed with an understanding of typical operating needs and expectations for the 20 meter band. HR20 5 This receiver circuit is ideal for discovering just how simple a true “Communications Receiver” can be . Thats right- there is a BIG difference between the Ramsey HR20 and other

17、 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 mi

18、nd, since both of these bands offer Novice and 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 HR20 is a “Direct Conversion” receiving circuit. Th

19、ere 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 o

20、f 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 desi

21、gned 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 pr

22、oduct detector can be made from simple diodes, or a pair of transistors, or a dual gate FET transistor, or various ICs. The Ramsey HR20 efficiently utilizes the Signetics SA602 IC for both the tunable oscillator and the product detector circuits, giving the equivalent of seven transistors in the mix

23、er-oscillator stages. HR20 6 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

24、. A common problem with DC receivers is that they are easily overwhelmed by strong AM broadcast stations from almost anywhere, whether its your local rock and roll broadcaster, Radio Moscow or the Voice of America. Even popular classics like Heath Kits HW-8 QRP transceiver exhibit this characteristi

25、c to a frustrating degree. Another problem with DC receivers is 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 speake

26、r or earphones. Still another problem is that of AC line hum whenever an unregulated power supply is used rather than batteries. The Ramsey HR20s 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

27、 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 active mixer and oscillator in a single 8-pin IC chip. L1 peaks the RF input to pin

28、s 1 and 2 of U1. L2, with varactor diode D1 and R2, C1, C2, and C4, control the resonant frequency of U1s 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

29、gain. C9 boosts the gain figure of the LM 386 from 20 to 50. HR20 7 PARTS SUPPLIED WITH THE HR20 KIT: CAPACITORS: ?1 15pF ceramic disc capacitor marked 15 or 15K (C4) ?1 27pF ceramic disc capacitor marked 27 or 27K (C13) ?2 36pF ceramic disc capacitor marked 36 or 36K (C1,C2) ?4 .01F disc capacitor

30、marked 103 or .01 or 10nF (C3,C5,C6,C7) ?2 4.7 to 10F electrolytic capacitor (C8,C9) ?3 100-220F 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: ?2 Shielded Coils mar

31、ked 42IF-123 (L1, L2) SEMICONDUCTORS: ?1 1N4002 Diode black epoxy style (D1) ?1 SA602 IC (U1) ?1 LM386 IC (U2) ?1 6.2 volt Zener Diode small grey 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 ante

32、nna 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 ?Antenna and suitable cable OPTIONAL: ?Ramsey Electronics Case and Knob kit, Model CHR or; ?Your own choice of en

33、closure and hardware HR20 8 LEARN-AS-YOU-BUILD RECEIVER ASSEMBLY STRATEGY: To help you learn just what exactly is going on well 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

34、 describe each individual components function as you build, but Ramseys 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

35、 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

36、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 falli

37、ng 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 should 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 potenti

38、ometer, 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 dont spend extra time troubleshooting we strongly recommend that you follow the assembly strategy and step-by-step procedures we have provided. H

39、R20 9 HR20 10 HR20 PARTS LAYOUT DIAGRAM HR20 11 RECEIVER ASSEMBLY: ?1. Install the RCA antenna jack, J1. Solder all four points. ?2. Install C5, a .01F 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

40、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. Examine inductor L1. Look at the bottom side and youll see a small silver and brown tubular part nested with

41、in the black plastic base. This is actually a ceramic tubular capacitor! It resonates with the tuned circuit for for 10.7 MHz. This is the wrong frequency for our purposes so well simply remove it and add our own external capacitor (C13). Removing the tubular capacitor is not as hard as you might ex

42、pect, simply crush it completely with a small screwdriver or knife. Omitting this step will prevent L1 from peaking on 20 meter signals. ?5. Install L1(marked 42IF-123), which tunes or preselects the signal input from the antenna through C5 and R1. ?6. Install C13, a 27pF ceramic disc capacitor (mar

43、ked 27 or 27K). ?7. 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 dont be afraid to solder U1 directly to the board a

44、s we have seen more repair problems with DIP sockets than from direct soldering of IC chips. The parts we have put in 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 C13. Inductor L1 allows us to match and

45、 tune the 20 meter band signals to the SA602s input. ?8. Install C6, .01F. 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. ?9. Install R4, 270 ohms (red-violet-brown), which drops the 9 volt battery su

46、pply to 6-7 volts, safe for the SA602. ?10. 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. ?11. Install C10, a 100-220F electrolytic capacitor. Electrolytic capaci

47、tors HR20 12 are marked by polarity and must be installed in the proper direction. Youll 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 t

48、he PC board. ?12. Install C11, a 100-220F electrolytic capacitor. Remember to observe correct polarity. C10 and C11 provide voltage stabilizing which directly improves the performance of the SA602 oscillator. ?13. Install C2, 36pF ceramic disc capacitor (marked 36 or 36K). It goes across pins 6 and 7 of the SA602 IC. T