Ramsey Electronics HR20 User Manual

20 meter (14 mhz) all mode receiver kit

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Instruction manual (28 pages)

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Page 1 20 METER (14 MHZ) ALL MODE RECEIVER KIT Ramsey Electronics Model No. HR20 Here’s 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: •...
Page 2 Ramsey Electronics publication No. MHR20 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.
Page 3: Table Of Contents
Ramsey Publication No. MHR20 Price $5.00 KIT ASSEMBLY AND INSTRUCTION MANUAL FOR HR20 AMATEUR RECEIVER KIT 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...
Page 4: Introduction To The Hr20
The Ramsey 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.
Page 5: About Direct Conversion
ABOUT DIRECT CONVERSION RECEIVERS: The HR20 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.
Page 6: Circuit Description
Still another problem is that of AC line hum whenever an unregulated power supply is used rather than batteries. The Ramsey HR20’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.
Page 7: Parts List
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 enclosure and hardware HR20• 7...
Page 8 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. HR20• 8...
Page 9: Schematic Diagram
HR20• 9...
Page 10: Parts Layout
HR20 PARTS LAYOUT DIAGRAM HR20• 10...
Page 11: Assembly Instructions
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 100-220µF electrolytic capacitor. Electrolytic capacitors HR20• 11...
Page 12 OPTION: with JMP-1 installed the bandspread of your tuning dial is the normal 250KHz. To get more bandspread in the ham band install C14 as shown in the parts diagram and install R7 (2.2k) in place of JMP-1. 24. Install S1, the power switch. HR20• 12...
Page 13 Congratulations! You have completed the assembly of your HR20 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.
Page 14: Initial Testing
INITIAL TESTING OF YOUR HR20: You’re now ready to power up and test your HR20, 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.
Page 15: Alignment
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 HR20. Your shortwave receiver is actually picking up the oscillator signal within the HR20!
Page 16: Using Your Hr20
Sideband (LSB), with Upper Sideband (USB) used for 20 - 18 - 15 - 12 - 10 Meter SSB. To check or ‘scan’ a given band for SSB signals, tune your HR20 up from the low end for USB signals and down from the high end for LSB.
Page 17 For Experienced Builders more information regarding audio output is in the general notes. The simple design of the audio stage of the Ramsey HR20 receiver assumes preference for headphone or small speaker operation, low battery drain and general economy.
Page 18 • MORE AUDIO POWER - ANOTHER WAY If you want to use your HR20 for casual band monitoring while you are busy across the room, in the shop, to share with a class or club or group and want LOTS more volume, try building up our very inexpensive Ramsey BN-9, 2 watt general purpose amplifier kit.
Page 19: Troubleshooting Guide
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! HR20• 19...
Page 20: Notes For Experienced Users
ALTERNATE POWER SOURCES: Most of the HR20 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.
Page 21 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. HR20• 21...
Page 22 You will experience a 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 HR20• 22...
Page 23 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 frequency response, but is does significantly boost the output of the SA602 reaching the LM386 audio amplifier IC.
Page 24 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! HR20• 24...
Page 25 CONSTRUCTION NOTES: HR20• 25...
Page 26: Warranty
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...
Page 27 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.
Page 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 ....11 Initial testing ......... 14 Alignment ........15 Troubleshooting guide ....

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