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20 MTR 20 WATT QRP
LINEAR AMPLIFIER KIT
Ramsey Electronics Model No.
Need a little extra boost for your QRP rig? Believe it or not, 20 watts is only
about an 'S' unit below a 100 watt rig! This nifty little amp will add some
"punch" to any QRP transmitter.
•
Works great with Ramsey QRP rigs or any other 1-2 watt
transmitters
•
Built-in T/R relay automatically switches between receive and
transmit
•
Runs on 12 volts DC at 2 to 4 amps; ideal for field day or battery
operation
•
Multistage low pass filter for a clean signal
•
Operates all modes: CW, SSB, or AM
•
Fast, easy, and fun 2 hour assembly
•
Informative manual answers questions on theory, hook-ups, and
uses - enhances resale value too!
•
Clear, concise assembly instructions carefully guide you to a
finished kit that works the FIRST time!
QAMP20 • 1
QAMP20
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Summary of Contents for Ramsey Electronics QAMP20
- Page 1 20 MTR 20 WATT QRP LINEAR AMPLIFIER KIT Ramsey Electronics Model No. QAMP20 Need a little extra boost for your QRP rig? Believe it or not, 20 watts is only about an ‘S’ unit below a 100 watt rig! This nifty little amp will add some “punch”...
- Page 2 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. QAMP20 • 2...
- Page 3 AND INSTRUCTION MANUAL FOR 20 METER QRP CW POWER AMPLIFIER KIT TABLE OF CONTENTS Introduction to the QAMP20 ... 4 How it works ........4 Parts list ......... 5 Learn as you Build ......6 QAMP20 assembly instructions ..7 Initial tests ..
- Page 4 The T-R relay circuit uses a simple diode detector consisting of D2 and D3. The detector output is amplified by transistors Q3 and Q4 to drive relay K1. QAMP20 • 4...
- Page 5 PARTS LIST FOR THE QAMP20 QRP POWER AMPLIFIER CAPACITORS: 1 100 to 220 µf electrolytic capacitor [C1] 1 10 µf electrolytic capacitor [C2] 4 .1 µf disc capacitors (marked .1 or 104) [C3,8,10,13] 2 180 ρf disc capacitors (marked 180 or 181) [C4,7] 330 ρf disc capacitors (marked 330 or 331) [C5,6]...
- Page 6 Take a look at the parts layout diagram. There is quite a lot to the construction of the QAMP20. It's easier than it seems once you get going, especially after you have installed a few of the "landmark" components. Once these "landmark"...
- Page 7 Both diode D3 and diode D2 are detectors for sensing applied RF power. 13. Install C10, .1 µf disc capacitor (marked .1 or 104). 14. Install R7, 100 K ohm resistor (brown-black-yellow). QAMP20 • 7...
- Page 8 28. Install C11, .001 µf disc capacitor (marked .001 or 102). 29. Install R9, another 270 ohm resistor (red-violet-brown). 30. Install C12, another .001 µf disc capacitor (marked .001 or 102). 31. Install C8, .1 µf disc capacitor (marked .1 or 104). QAMP20 • 8...
- Page 9 - for that "old-world craftsmanship" touch! We'll prepare all those parts now for further assembly. We supplied plenty of enameled wire for your kit but if you mess up, you can get a whole 50' spool of it from Radio Shack (278-1341). QAMP20 • 9...
- Page 10 44. Cut off another length of the same wire, 8 inches long. Wind 1 turn through the core, loop out 1 inch, twist together and run one more turn 14 turns through center of core IMPORTANT: Loop the first winding around the front of the core as shown. QAMP20 • 10...
- Page 11 48. Install the larger transformer (T1) into the indicated location on the PC board. 49. Install L1, a 12 turn toroid inductor wound previously. If desired, a small dab of hot melt glue, bathtub sealer, or caulk may be used to secure the toroids. QAMP20 • 11...
- Page 12 2. Connect a multimeter to TP1; set the meter to read up to 5 volts DC 3. Connect a dummy load to J1, the amplifier RF output. In a pinch, a light bulb may be used - see the section, "Verifying RF Power Output." QAMP20 • 12...
- Page 13 VERIFYING TRANSMITTER RF OUTPUT The most important thing to know is whether your transmitter is delivering some measurable and reassuring level of RF power. Then you can continue on to adding the QRP amplifier and checking out the whole set-up. QAMP20 • 13...
- Page 14 Amateur radio magazines and handbooks provide a variety of circuits for RF wattmeters and relative field-strength indicators, including methods of using your VOM as an indicating device. CQ magazine for March 1990 offers an article by QAMP20 • 14...
- Page 15 RF path through the relay. The amplifier should draw about ¼ amp with no signal applied. If you see more than that, recheck the bias setting (see the section "INITIAL TESTS"). QAMP20 • 15...
- Page 16 These sturdy black instrument cases are supplied with neatly lettered front and rear panels, switch knobs, rubber feet and mounting screws. QAMP20 • 16...
- Page 17 Ramsey amateur kit board is Radio Shack No. 270-253A. This metal utility cabinet can accommodate both a receiver, transmitter and amplifier board, plus speaker, with room for various refinements you might like to add. PARTS LAYOUT QAMP20 POWER AMPLIFIER KIT QAMP20 • 17...
- Page 18 QAMP20 • 18...
- Page 19 '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 supplied with the basic kit by Ramsey, please write or call us with information on the part you need and proof of kit purchase.
- Page 20 • Digital Multimeter Ramsey M133 Price: $5.00 Ramsey Publication No. MQAMP20 Assembly and Instruction manual for: RAMSEY MODEL NO. QAMP20 20 METER 20 WATT LINEAR AMPLIFIER KIT RAMSEY ELECTRONICS, INC. 590 Fishers Station Drive Victor, New York 14564 This Quality Electronics...