Ramsey Electronics QRP20 Bedienungsanleitung

QRP-20 •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.

•Ideal for portable or travel fun

•VCXO design allows up to 8 - 10 KHz of tuning about the crystal

frequency

•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 •2

RAMSEY TRANSMITTER KITS

• The “Cube” MicroStation Transmitter

• FM25B Synthesized FM Transmitter

• FM100B Stereo FM Transmitter

• AM1 AM Transmitter

• AM25 Synthesized AM 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

• BS1 “Bullshooter” Digital Voice Storage Unit

• AVS10 Automatic Sequential Video Switcher

• WCT20 Cable Wizard Cable Tracer

• LC1 Inductance-Capacitance Meter

RAMSEY AMATEUR RADIO KITS

• DDF1 Doppler Direction Finder

• HR Series HF All Mode Receivers

• QRP Series HF CW Transmitters

• CW7 CW Keyer

• CPO3 Code Practice Oscillator

• 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.

20 METER CW TRANSMITTER KIT INSTRUCTION MANUAL

Ramsey Electronics publication No. QRP20 Revision 1.3

First printing: January 1995

written permission of Ramsey Electronics, Inc. Printed in the United States of America.

QRP-20 •3

QRP20 20 METER CW

TRANSMITTER KIT

Ramsey Publication No. QRP20

Price $5.00

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 .................. 11

QRP20 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

KIT ASSEMBLY

AND INSTRUCTION MANUAL FOR

RAMSEY ELECTRONICS, INC.

590 Fishers Station Drive

Victor, New York 14564

Phone (585) 924-4560

Fax (585) 924-4555

QRP-20 •4

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 "QRP20-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!

QRP-20 •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" 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 S-

meter. Assume identical dipole antennas at both stations. Our chart does not

QRP-20 •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

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!

QRP-20 •7

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.

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

build up the confidence that comes with actually making contacts and that they

do not need the additional challenge and pressure of low-power operation.

There is some wisdom in this view, but that opinion should not make

newcomers apprehensive about trying a Ramsey QRP transmitter, IF:

1. This is where your budget is.

2. You can count on somebody to help you with assembly.

3. You can count on somebody to listen to your signal during initial tests.

4. You have a reasonably good receiver.

5. You have space for a normal, no-compromise antenna for the band you

wish to operate, either a standard dipole, or the "inverted V" dipole, or

quarter-wave vertical.

CIRCUIT DESCRIPTION:

In brief, Q1 is a crystal oscillator, amplified by buffer stage Q2, which drives Q3

as the RF output amplifier. Q4 is a PNP keying circuit which opens and closes

the 12VDC supply line to Q1 and the T-R circuitry of D1 and D2.

S1 selects either of two crystals. R1,D3,D4 and L1 form a varactor controlled

series resonant circuit with the crystal. Adjusting R1 permits a crystal frequency

swing of up to 7 KHz, about the crystal frequency.

QRP-20 •8

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.

When the keying line is closed, Q4 conducts +12VDC to the oscillator stage,

applies a positive bias to the base of Q2 through R8, and +12VDC through

choke L4 to the anode of D1, which permits RF to pass through D1 to the filter

network while applying negative bias to D2 which blocks RF from passing to the

receiver. When the keying line is open, the +12VDC applied to D2 through R13

permits D2 to conduct from the antenna jack to the receiver jack. The buffer

and amplifier stages are not keyed, resulting in clean keying, free of chirps and

clicks.

BLOCK DIAGRAM:

OSC.

BUFFER Q3

FINAL

AMP

D1,D2

DIODE

SWITCH

C17.L5,C18

LOW PASS

FILTER

QRP-20 •9

PARTS SUPPLIED WITH QRP20 TRANSMITTER KIT:

CAPACITORS:

1 47 pf capacitor (C6)

2 68 pf capacitor (C2,C12)

2 220 pf capacitor (marked 220 or 221) (C17,C18)

1 330 pf capacitor (marked 330 or 331) (C3)

11 .01 uf capacitors (marked .01 or 103 or 10 nf)

(C1,4,5,7,8,9,10,13,14,15,19)

1 100 to 220 uf electrolytic capacitor (C16)

INDUCTORS:

3 100 uh inductor (looks like a resistor with brown-black-brown-gold or silver

bands) (L2,L4,L5)

1 2.2 uh inductor (green body with: red-red-gold-black color bands) (L1)

2 1.0 uh inductor (brown form with wire wrapped around body) (L3,L6)

RESISTORS:

3 100 ohms [brown-black-brown] (R7,R9,R11)

1 270 ohms [red-violet-brown] (R10)

1 470 ohms [yellow-violet-brown] (R6)

2 1K ohms [brown-black-red] (R12,13)

4 10K ohms [brown-black-orange] (R4,5,14,15)

1 47K ohms [yellow-violet-orange] (R8)

2 1 megohm [brown-black-green] (R2,3)

1 10K potentiometer (R1)

SEMICONDUCTORS:

1 2N3904 NPN transistor (Q1)

2 2N3053 NPN transistor (Q3,Q2)

1 PNP transistor (Q4) (marked 221-334) (similar to 2N3906)

1 1N4148 diode (small glass diode)

1 1N4002 diode (large black epoxy diode)

2 varactor diodes in TO-92 style case (D3,D4)

HARDWARE, OTHER COMPONENTS, MISC.:

1 Crystal "A" (14.060 MHz)

1 QRP-TX printed circuit board

1 heatsink for Q3

3 RCA-style jacks (J1,2,3)

1 DC power jack (J4)

1 pushbutton switch (S1)

REQUIRED, NOT SUPPLIED:

12-14 volt 500 ma DC power source

Key, keyer or computer interface terminated to RCA plug

RF output indicator (see text)

14 MHz antenna and/or 50 ohm dummy load

QRP-20 •10

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