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20 METER (14MHz)
CW TRANSMITTER
Ramsey Electronics Model No.
THE RAMSEY QRP20 IS AN AMAZING PERFORMER
THAT WILL WORK THE WORLD ON ABOUT A WATT!
FOLKS OF ALL AGES HAVE SUCCESSFULLY BUILT
AND ENJOYED THIS EASY, FUN KIT.
•
Ideal for portable or travel fun
•
VCXO design allows up to 8 - 10 KHz of tuning about the crystal
frequency
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Front panel switching of TWO channels and includes a crystal for
14.06 MHz, the International QRP frequency
•
Excellent and clean keying waveform
•
Built-in antenna T-R switch
•
Operates on 12 - 15 volts DC at 1/4 amp current
•
Appoximately 1 Watt RF power
•
Clear, concise step-by-step instructions carefully guide you to a
finished kit that not only works - but you'll also learn too!
•
Proven design that has won many of awards for operators around
the country!
•
Add our case and knob set for a finished 'Pro' look. Cases match all
Ramsey products
QRP-20 • 1
QRP20
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Summary of Contents for Ramsey Electronics QRP20
- Page 1 20 METER (14MHz) CW TRANSMITTER Ramsey Electronics Model No. QRP20 THE RAMSEY QRP20 IS AN AMAZING PERFORMER THAT WILL WORK THE WORLD ON ABOUT A WATT! FOLKS OF ALL AGES HAVE SUCCESSFULLY BUILT AND ENJOYED THIS EASY, FUN KIT. •...
- Page 2 Ramsey Electronics publication No. QRP20 Revision 1.3 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.
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Page 3: Table Of Contents
KIT ASSEMBLY AND INSTRUCTION MANUAL FOR QRP20 20 METER CW TRANSMITTER KIT TABLE OF CONTENTS Introduction to the QRP20 ..... 4 Understanding Power Levels ..5 QRP20 Circuit Description ..... 7 Block Diagram ........ 8 Parts List ........9 Schematic Diagram ...... 10 Parts Layout Diagram .... - Page 4 And that is part of what ham radio can be all about. The purpose of the Ramsey Electronics series of QRP transmitters is to give our amateur radio customers the option of picking up a...
- Page 5 If you're studying this manual before deciding to try this Ramsey "QRP" transmitter project, perhaps the following discussion will be helpful to you. The purpose of this manual is to help you construct this Ramsey Electronics 4- stage, variable-frequency CW transmitter efficiently and successfully, not necessarily to "sell"...
- Page 6 start at the proverbial "30 db. over S-9" and work itself down to S-1 for reasons that will become obvious. S9+10 db. 1000 watts output 100 watts output 25 watts output 6.25 watts output 1.56 watts output .39 watts output We can see that it becomes easy to play games with such numbers.
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Page 7: Circuit Description
On the other hand, if you hear a 1000 watt station producing a moderate signal such as S4 or S5, you can reasonably assume that you will not have a lot of luck over that path right now with the theoretical S1 signal level of your QRP transmitter. -
Page 8: Block Diagram
Q3 is a Class C RF amplifier that amplifies the RF output of Q2 to the final RF power output level. L6,C17 and C18 form a low pass filter (Butterworth) to match the output of Q3 to the antenna and reduce harmonics to acceptable levels as specified by the FCC. - Page 9 PARTS SUPPLIED WITH QRP20 TRANSMITTER KIT: CAPACITORS: 47 pf capacitor (C6) 68 pf capacitor (C2,C12) 220 pf capacitor (marked 220 or 221) (C17,C18) 330 pf capacitor (marked 330 or 331) (C3) 11 .01 uf capacitors (marked .01 or 103 or 10 nf)
- Page 10 QRP-20 • 10...
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Page 11: Parts Layout Diagram
QRP20 PARTS LAYOUT DIAGRAM: QRP-20 • 11... - Page 12 "LEARN-AS-YOU-BUILD" TRANSMITTER ASSEMBLY STRATEGY: As you can see in examining the circuit board and components, there is a bit more to this transmitter kit than soldering a few parts and putting a signal on the air. So that you don't spend extra time "troubleshooting" instead of getting on the air, we strongly recommend you follow the assembly strategy and step-by- step procedures we are providing.
- Page 13 5. Insert and solder R1, the 10K tuning potentiometer. 6. Insert and solder S1, pushbutton switch. Carefully select, insert and solder the following components in the order given in the following steps. Check off each step as completed. 7. C16, 100 to 220 uf electrolytic. Electrolytic capacitors are polarized, which means there is a right and a wrong way to install them! Generally, the Negative ( - ) side is indicated on the capacitor, while the Positive ( + ) is shown on the PC board.
- Page 14 18. Install R14, 10K ohms [brown-black-orange]. 19. Install Q4, be sure to orient its flat side correctly as shown. 20.Install C15, .01 uf (marked .01 or 103 or 10 nf). So far, here's what we've accomplished. First, we've got over a third of all the parts soldered onto the board, which should make you happy, and you should be used to locating the correct component holes with increasing ease by seeing them in relation to previously installed components.
- Page 15 29. Install C3, 330 pf (marked 330 or 331). 30. Install R6, 470 ohms (yellow-violet-brown). With the above components installed correctly, the three holes for Q1 should be clearly apparent. Make sure Q1 is correctly identified as a 2N3904. 31. Install Q1, 2N3904. Orient its flat side correctly. 32.
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Page 16: Crystal Oscillator Testing
CRYSTAL OSCILLATOR TESTING: ◊ Connect a key, keyer or momentary switch to J3. ◊ Connect +12VDC to power connector J4. Note that the CENTER connection is the positive (+) side. ◊ Tune a nearby receiver to the anticipated crystal frequency. ◊... -
Page 17: Initial Tests
"halftime" instructions, NOW is the time to make proper preparations for testing and using your transmitter. As we suggest in all Ramsey Electronics kit projects, now might also be an excellent time to take a break and then come back to re-check your connections, or have a friend go over them. - Page 18 14 to 15 volts DC. The easiest method is to place two fresh "D cells" in series with your power source, if a full 13.6-15 volts DC is not available. If your supply voltage is in the 11-12 volt range, you can expect a 200 to 250 ma current flow and about one-half watt of the RF output power.
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Page 19: Maximizing Rf Power Output
Please remember, though, that a flashlight bulb does NOT present the proper load impedance to the transmitter output, so theoretical calculations based on the bulb`s rating can only be approximate. For example, the PR-4 at full brilliance presents only an 8.2 ohm load to the transmitter. If ANY flashlight bulb lights up when connected to the antenna jack of this transmitter, you can be satisfied that you have RF output power ROUGHLY comparable to the DC power rating of the bulb you are using. - Page 20 THE RAMSEY ELECTRONICS CASE, KNOB & HARDWARE OPTION: Your finished transmitter can be installed in a variety of enclosures of your own design and choosing.
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Page 21: Troubleshooting Guide
FINAL CONSIDERATIONS: Our earlier discussion of how a watt of RF output can indeed offer satisfying communications has several presuppositions: 1. A resonant antenna (dipole or quarter-wave vertical) 2. Good quality coaxial feedline and connectors 3. An effective earth ground We cannot expect good results from low levels of RF output if the power gets wasted in lousy coax, corroded connections, or poor antennas. - Page 22 QRP-20 • 22...
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Page 23: Ramsey Kit Warranty
'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... -
Page 24: Ramsey Electronics, Inc
20 METER CW TRANSMITTER KIT Quick Reference Page Guide Introduction to the QRP20 ....4 Understanding power levels ... 5 QRP20 Circuit description ....7 Parts list .......... 9 Schematic Diagram ...... 10 Parts layout diagram ....11 QRP20 Assembly instructions ..12 Initial tests ........