Ramsey QRP80 User Manual

80 METER (3.5 MHz)
CW TRANSMITTER

Ramsey Electronics Model No. QRP-80

THE RAMSEY QRP-80 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 5 KHz of tuning about the crystal

frequency

• Front panel switching of TWO channels and includes a crystal for

3.579 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!

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RAMSEY TRANSMITTER KITS

• FM-10 FM Stereo Transmitter

• FM-1,2,3,4 FM Wireless Microphones

• PB-1 Telephone Transmitter

RAMSEY RECEIVER KITS

• FR-1 FM Broadcast Receiver

• AR-1 Aircraft Band Receiver

• SR-1 Shortwave Receiver

• AA-7 Active Antenna

• SC-1 Shortwave Converter

RAMSEY HOBBY KITS

• SG-7 Personal Speed Radar

• SS-70 Speech Scrambler

• TT-1 Telephone Recorder

• SP-1 Speakerphone

• MD-3 Microwave Motion Detector

• PH-10 Peak hold Meter

• LC-1 Inductance-Capacitance Meter

RAMSEY AMATEUR RADIO KITS

• FX Series VHF and UHF Transceivers

• HR Series HF All Mode Receivers

• QRP Series HF CW Transmitters

• CW-700 Micro Memory CW Keyer

• PA Series VHF and UHF Power Amplifiers

• Packet Computer Interfaces

• QRP Power Amplifiers

RAMSEY MINI-KITS
Many other kits are available for hobby, school, Scouts and just plain FUN.
New kits are always under development. Write or call for our free Ramsey
catalog.

80 METER CW TRANSMITTER KIT INSTRUCTION MANUAL

Ramsey Electronics publication No. QRP-80 Revision 1.3

COPYRIGHT 1994 by Ramsey Electronics, Inc. 793 Canning Parkway, 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.

First printing: January 1995

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Ramsey Publication No. QRP-80

Price $5.00

KIT ASSEMBLY

AND INSTRUCTION MANUAL FOR

QRP-80 80 METER CW
TRANSMITTER KIT

TABLE OF CONTENTS

Introduction to the QRP-80 ............ 4

Understanding power levels ........... 5

Circuit description ........................... 7

Simplified Block diagram ................ 8

Parts list ......................................... 9

Schematic Diagram ...................... 10

Parts layout diagram .................... 11

Assembly instructions .................. 12

Crystal oscillator testing ............... 16

Initial tests .................................... 17

Verifying RF power ....................... 18

Maximizing RF power output ........ 19

Options for finishing project .......... 20

Enclosure ideas ............................ 20

Choosing crystals ......................... 20

Troubleshooting guide .................. 21

Ramsey kit warranty ..................... 22

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RAMSEY ELECTRONICS, INC.

793 Canning Parkway

Victor, New York 14564

Phone [phone]

Fax [phone]

INTRODUCTION:

Most "QRP" transmitters are one-of-a-kind experimental circuits which take some
patience and fine-tuning to get clean keying and satisfactory performance. Most
QRP building projects presume either unlimited radio junkboxes with all the right
coils and capacitors, or that you have a lot of time on your hands to track down
needed parts. 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 truly complete and reliable transmitter kit for
whenever you need a compact CW rig for a particular opportunity, perhaps a
camping or business trip or a weekend contest, or something economical to
share with a favorite new Novice.

This transmitter is a serious and practical device for radio amateurs with general
interests, as well as for QRP enthusiasts.

NOTE TO NEWCOMERS: "QRP" is amateur radio shorthand referring to
operation at "reduced power". As a standard "QRP-80-signal", the CW
expression "QRP?" really means all of this: "If you are receiving me so well, and
since the FCC requires that we use minimum power necessary to maintain useful
communication, do you think I should reduce transmitting power?" The act of
reducing power output can be the switching off of a linear power amplifier, or
switching from 25 to 5 watts on your new Radio Shack 10 meter rig or turning
back the carrier level control on most modern transceivers. For equipment
description and contest competition purposes, "QRP" refers to transmitter powers
under 5 watts.

In our manuals for the Ramsey Amateur Band receivers for the 80 and 40 meter
bands, which tend to be of interest to many beginners because of available
Novice and Technician operating privileges, we try to be very basic and patient,
hoping that such an approach will be helpful to radio newcomers - as well as to
casual, licensed amateurs who just did not know that worthwhile radio gear could
be constructed at Ramsey's low prices, even in the 1990's.

Talking through a transmitter project presents a different challenge. Talking
through a multi-stage transmitter that delivers a grand total of one or two watts to
your antenna is an even greater challenge. In these times when a "barefoot rig"
is assumed to be an imported, digitally-synthesized transceiver putting out over
100 watts at a cost of $1000-2000.00, we need a sensible and helpful way of
talking about this QRP transmitter you are about to construct.

It's easy to prove that Ramsey's popular and economical receivers work just fine.
Build one right, turn it on, and we become easily convinced. A transmitter is a
different story, especially a transmitter that runs low QRP power! Different from a
receiver, you want to see some measurable output power and you especially
want to make two-way contacts!

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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 4­stage, variable-frequency CW transmitter efficiently and successfully, not
necessarily to "sell" you on the merits and fun that have been discovered in
ham QRP operation. The purpose of the following discussion of power levels
and signal reports is simply to assure you that your new Ramsey QRP
transmitter is capable of serious, long-distance communication.

1000 WATTS vs 1 WATT: UNDERSTANDING THE DIFFERENCE

Before we move on, I would like to share with you a practical formula about
transmitter power that I clung to in my younger years when I could not afford
anything other than my original Novice CW transmitter, even well after I got my
Extra Class license. First, some theoretical facts we should know:

• 1. An "S-unit" on a receiver's S-meter or in the R-S-T system consists of a

6 - decibel increase or decrease of output power received from a
transmitter.

• 2. Power needs to be increased four times or 400% to result in a true 1 S-

unit or 6db RST gain.

• 3. Reducing output power down to 25% of previous power should result in

an S- Meter or RST drop of only one 6-db unit.

• 4. A 10 - decibel increase in signal strength requires a power increase of

• ten times!

Next, there are three practical facts to remember:

• 1. The R-S-T system was designed originally for the human ear and was

based on typical receiver performance of over 50 years ago.

• 2. Modern receiver design permits signals which are technically "weak" in

measured decibels to sound quite good (ie: 569-579) to the ear.

• 3. The human ear is sensitive enough to appreciate a 1 or 2 db change in

signal strength, which is why moderate changes in output power often
result in more dramatic signal report changes. (In fact, the value of a
decibel was determined to be that increment of sound change which
the ear could detect!)

The following example shows RST reports to be expected, in exact theory, at
various power reduction levels. We will start with the classic 1000 watt station
which gets a report of "10 db. over S-9" measured on the receiving station's S­meter. Assume identical dipole antennas at both stations. Our chart does not
start at the proverbial "30 db. over S-9" and work itself down to S-1 for reasons

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that will become obvious.

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S9+10 db. 1000 watts output
S9 100 watts output
S8 25 watts output
S7 6.25 watts output
S6 1.56 watts output
S5 .39 watts output

We can see that it becomes easy to play games with such numbers. For
example, an RST of 439 is a legitimate report which permits reasonably
effective communication. But, do we believe that the transmitting station
illustrated above could really produce a 439 signal by running .0013 watt? If we
say "probably not", we also ask why not, and then we would get the seminars
about perfect antenna matching, transmission line losses, and so forth.

Under good propagation conditions, SSB signal reports of "20 over S-9" and
more can be given without even needing 1000 watts or a beam antenna.
Assuming the "+20" is an accurate report, consider this example of power
reduction over the same path:

S9+20db. 1000 watts
S9+10db. 100 watts
S9 10 watts
S8 2.5 watts
S7 .625 watts
S6 .156 watt
S5 .039 watt
S4 .0087 watt!

Under reasonably good band conditions, particularly at 10 or 14 MHz and on
up, the above correlation of signal reports to power output becomes realistic.
"S9+20" is what amplifier users expect to give and receive to justify their
investment and power consumption. Most commercial transceivers have typical
output in the 60-200 watt range, and S8-9 reports are taken for granted.
Actually, 15-25 watts is a far more practical operating power than most
amateurs and equipment vendors realize today...and the thousands of QRP
enthusiasts will confirm that getting a solid 579 running 3-4 watts is no big deal.

If all the above theoretical signal reports are based on both the transmitting and
receiving stations using simple dipole antennas, we can also see that the use of
some 10db gain antenna such as a beam or quad by either station could move
the S7 for .625 watt up to S8, and that a similar antenna used at the other
station could give the under 1 watt signal a further boost over S9!

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

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transmitter.

While these figures also can be used to show how nice it is to have a power
amplifier and beam antenna, they indeed serve to show that reasonable signal
levels indeed are achievable with low power and a dipole antenna.

"QRP" enthusiasts have their own rituals, jargon, strategies, QRP operating
contests, magazine columns and books, and convention get-togethers. They
constitute a vital segment of the amateur radio community, because they
consistently demonstrate the feasibility of low-power communication. In fact,
the most avid QRP enthusiasts would not regard communication with a
Ramsey transmitter especially challenging, since they prefer the new world of
milliwatt operation, known as "QRPp"! And, yes, the ones who have conquered
the "milliwatt" world ARE setting records with "milliwatt" tests. With the world
record set in 1970 between Alaska and Oregon on ONE microwatt, think about
it this way: your Ramsey QRP transmitter is almost one million times more
powerful than the transmitter used in that historic test!

WHO SHOULD USE A "QRP" TRANSMITTER?

There is a philosophy that "Novices" should not get started with a very low
power transmitter. The reasoning is that most newly-licensed amateurs need to

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