40 METER (7.0 MHZ) ALL MODE RECEIVER KIT Ramsey Electronics Model No.
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 KI
Ramsey Publication No. MHR40 Price $5.00 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR HR40 AMATEUR RECEIVER KIT 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 .................................
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.
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.
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.
PARTS SUPPLIED WITH THE HR40 KIT: CAPACITORS: 1 .001µF disc capacitor [marked 102, .001 or 1nF] (C3) 3 100pF disc capacitor [marked 100 or 101K] (C1,C2,C4) 3 .01µF disc capacitor [marked 103 , .01 or 10nF] (C5,C6,C7) 2 4.
"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.
HR40 • 9
PARTS LAYOUT: HR40 • 10
RECEIVER ASSEMBLY: 1. Install the RCA antenna jack, J1. Solder all four points. 2. Install C5, a .01µF 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.
capacitor is a first step in setting 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, .001µF 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).
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.
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.
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.
USING YOUR RECEIVER: In your first tests, 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.
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.
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.
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.
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.
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.
OTHER METHODS OF DIAL CALIBRATION: A easy way of making your own dial is to paste a small rectangle of paper behind the 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.
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 signal of the SA602 by a factor of 1000.
CONSTRUCTION NOTES: HR40 • 24
HR40 • 25
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 your assurance that a team of knowledgeable people have field-tested several "copies" of this kit straight from the Ramsey Inventory.
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.
HR40 AMATEUR RECEIVER KIT Quick Reference Page Guide Introduction to the HR40 .................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 ...............
