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Ramsey Electronics HR20 - page 1
20 METER (14 MHZ) ALL MODE RECEIVER KIT Ramsey Electronics Model No. HR20 Here’s the ideal mini-receiver fo r catching all the busy action on 20 meters from your of fice, home or on trips! Small in si z e but BIG in features: • Easily tunes SSB, CW, RTTY and AM • Smooth varactor tuning of any desired 250KHz segment of the 20 meter band, easil ...
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Ramsey Electronics HR20 - page 2
HR20 • 2 P ARTIAL LIST OF AVAIL ABLE KI TS RA MSEY TRA NSMIT TER KITS • FM10A, FM25B Stereo Transmitters • AM1, A M25 AM Transmi tter s • TV6 Telev ision Transmitte r • FM100B Professional FM Stere o Transmitter RAMSE Y RECEI VE R KITS • FR1 FM Broadcast Receiver • A R1 Aircraft Ba nd Receiver • SR2 Shortwave Receiver • AA ...
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Ramsey Electronics HR20 - page 3
HR20 • 3 HR20 AMA TEUR 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 . ...
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Ramsey Electronics HR20 - page 4
HR20 • 4 INTR OD UC TIO N: 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 there’s something interesting happening on 20 meters. There are several groups of people who will enjoy this Ram sey HR20 Receiver: • Experienced Ham operators w ho want a simple extra ...
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Ramsey Electronics HR20 - page 5
HR20 • 5 This receiver circuit is ideal for discovering ju st how simple a true “Communications Receiver” can be . That ’s right- there is a BIG diff erence between the Ra m sey HR20 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 k ...
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Ramsey Electronics HR20 - page 6
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 co uld even be set up to serve directl y as a transmitter VFO in a simple transceiver setup. A common problem with DC receivers is that they are ...
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Ramsey Electronics HR20 - page 7
HR20 • 7 PARTS SUPPLIED WITH THE HR20 KIT: CAPA CIT ORS : 1 15pF ceramic disc capacit or [m arked 15 or 15K] (C4) 1 27pF ceramic disc capacitor [mar k ed 27 or 27K] (C13) 2 36pF ceramic disc capacitor [mar k ed 36 or 36K] (C1,C2) 4 .01µF disc capacitor [marked 103 or .01 or 10 nF] (C3,C5,C6,C7) 2 4.7 to 10µF electr olytic ca ...
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Ramsey Electronics HR20 - page 8
HR20 • 8 "LEARN-AS-YOU-BUILD " RECEIVER 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 boar d sim ple, we will not be able to fully describe each individual component’s functi ...
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Ramsey Electronics HR20 - page 9
HR20 • 9 ...
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Ramsey Electronics HR20 - page 10
HR20 • 10 HR2 0 PART S LAY OUT DIA GRAM ...
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Ramsey Electronics HR20 - page 11
HR20 • 11 RECEIVER ASSEMBLY: 1. Install the RCA antenna jack , J1. Solder all four points. 2. Install C5, a .01µF ceramic disc signal coupling capacitor . Th is 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 in ...
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Ramsey Electronics HR20 - page 12
HR20 • 12 are marked by polarity and must be installed in the proper dire ction. You’ll see that one side of the capacito r has a black band and is m arked w ith a ‘-’ sign. This is the negative side, the ot her side is the posi tive lead. Make sure you in sert the p ositive lead into the ‘+’ marked hole on the PC board. 12. Install ...
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Ramsey Electronics HR20 - page 13
HR20 • 13 25. Install the 9-volt battery snap connector, making sure that the red (+) and black (-) leads are co rrectl y installed . 26. Install C7, .01µF disc capacitor (marked 103 or .01 or 10nF). 27. Install C8 , 4.7-10µF e lectrol ytic capacitor. Observe polarit y. 28. Install U2, the LM386 audio amplifier IC chip. Just lik ...
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Ramsey Electronics HR20 - page 14
HR20 • 14 INITIAL TESTING OF YOUR HR20: You’re now re ad y to power up and test your HR20, but before you begin take some time to sweep off your bench of any loose c omponent leads or solder splashes. A clean work area not o nl y makes testing less frustrating but also less prone to proble m s. REQUIRED FOR INITIAL T ESTING AND ALIGNMENT: A kno ...
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Ramsey Electronics HR20 - page 15
HR20 • 15 Align men t: Turn on whatever re f erence signal source you plan to use. This can be a regular transceiver keying a few milli watts 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 receive r. If you are without any reference signal what s oever but have ...
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Ramsey Electronics HR20 - page 16
HR20 • 16 USING YO UR RECEIVER: In your first tests, you might f eel 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 w ill result in more comfortable tuning right away. Also, the larger the knob, the easier tuning is. Even smoother co ...
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Ramsey Electronics HR20 - page 17
HR20 • 17 SA602 audio output at the vo lum e control, and switch in a pleasant oscillator pitch (keying sidetone) which is amplified to listening leve l b y LM386. The Ramsey Electronics Universal timer kit No. UT-5 is easily adapted as a sidetone oscillator. • SPEAKER OPERATION A fifty cen t, two inch diameter speaker, ly ing naked on your w o ...
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Ramsey Electronics HR20 - page 18
HR20 • 18 • MORE AUDIO POWER - ANOTHER WAY If you want to use your HR20 for casual band monitoring w hile you are busy across the room, in the shop, to share w ith a cl ass or club or group and want LOTS m ore volume, t ry building up our very inexp ensive Ra msey BN-9, 2 watt general purpose amplifier kit. Supply DC vo ltage to such an amplifi ...
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Ramsey Electronics HR20 - page 19
HR20 • 19 TROU BL ES HOO TI NG TIP S: PROBLEM: ALL signals are chirpy and unstable. SOLUTION: Sorry to have to sa y it , bu t this condit ion is only caused by a weak battery ! Use a fresh alkaline cell. Any strong signal forces the audi o circuit to rob voltage from th e oscillator, which cause the instability. PROBLEM: Occasionally good but err ...
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Ramsey Electronics HR20 - page 20
HR20 • 20 GENERAL NOTES FOR EXPERIENCED QRP BUILDERS: W e at Ramsey Electronic s deliberately designed the HR-series of DC receivers to be easil y available, aff ordab le and builda ble b y any person willing to follow the assembly di r ections. To achieve this goal, the current models, with direct coupling of the SA602 to the LM386 operating wit ...
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Ramsey Electronics HR20 - page 21
HR20 • 21 BANDSPREA D AND TUNING R ANG E: The easiest way to enjoy finer tuning , if you plan to use your receiver only for checking your favorite segm ent of the band, is to ad just the oscillator coil so that your desired segment f alls within the second half of the rotation range of the tuning contro l. The first half of the rotation range cov ...
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Ramsey Electronics HR20 - page 22
HR20 • 22 FR EQU EN CY S T ABIL I TY: A kilohert z of drift is not a big deal in FM circu its or a short wave broadcast configuration, but ANY freq uency instability is ann oying when trying to recei ve CW or SSB. The varactor - controlled Lo cal Oscillator is indeed a VFO, and therefore needs all the consideration given to any VFO circuit. Even ...
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Ramsey Electronics HR20 - page 23
HR20 • 23 another way of getting bandspread for y o ur 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 ...
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Ramsey Electronics HR20 - page 24
HR20 • 24 The ‘-’ side of the new capacitor is connected to the circuit trace leading to t he volume control. Mount this capacitor as close to the body of the new LM386 as possible. Keep all lead s as short as possible. This modification results in very good speaker volume but will also require closer attention to battery quality and conditio ...
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Ramsey Electronics HR20 - page 25
HR20 • 25 CONSTRUCT ION NOTES: ...
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Ramsey Electronics HR20 - page 26
HR20 • 26 The Ramsey Kit Warranty Please read carefully BEFORE calli ng or w riting in about y our kit. Most problems can be solved without contacting th e factory. Notice that this is not a " fine print" warrant y. We want y ou to understand your rights and ours too! All Ra mse y kits will work if assembled properly. The very fact that ...
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Ramsey Electronics HR20 - page 27
HR20 • 27 3. F ACTOR Y REP A I R O F A S SEM BLE D KI TS: To qualify for Ramsey Electronics factory repair, kits M UST: 1. NOT be assembled with acid core solder or fl ux. 2. NOT be modified in any manner. 3. BE returned in f ully-assembled form, not partially ass embled. 4. BE accompanied by the proper repair fee. No repair will be undertaken un ...
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Ramsey Electronics HR20 - page 28
HR20 • 28 HR20 AMATEUR RECEIVER KIT Quick Reference Page Guide Introduction to the HR20 . ............... 4 Circuit description ....................... .... 6 Parts list .............................. ........... 7 Schematic diagram ........................ 9 Parts layout .... ................. ............. 10 Assembly instructions ............. ...
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