QRP Labs
Crystal Sets to Sideband PDF Print E-mail
Written by Hans Summers   
Monday, 29 June 2009 17:36

Revision 10, July 2006

A Guide to Building an Amateur Radio Station

By Frank W. Harris, KØIYE

Copyright © Frank W. Harris, 2002, 2004, 2006

NOTE: There is a Spanish translation of this book here:




Table of Contents:



Chapter 1


  • Exploring the shortwave bands
  • Growing up in the Morse code era
  • The joy of building it yourself
  • A brief history of radio communication
  • Henry, Maxwell, Hertz, Tesla and Marconi.
  • Fessenden, Edison, Flemming, DeForest and Armstrong
  • The sinking of the RMS Republic and the birth of ham radio
  • Ham radio in the last 80 years
  • Becoming a radio amateur


Chapter 2


  • What qualifies as homebuilding?
  • When homebrewing is not appropriate
  • Barriers to modern homebuilding
  • Time, frequency stability and lead inductance
  • Basic electrical knowledge
  • Magnets & static electricity
  • Voltage, current, resistance, energy and power
  • (Illustrated with drawings of water & mechanical analogies)
  • Conductors, Insulators and semiconductors
  • Capacitors, inductors, transformers & alternators
  • Home power distribution, transformers at low and high frequencies


Chapter 3


  • R&D as recreation
  • How to build radios (or anything else) in your basement
  • Persistence, read books, keep a notebook, & work in small increments
  • Minimum tools needed
  • The ARRL Amateur Radio Handbook
  • Soldering irons and small tools
  • Drills & thread taps
  • Wood carving gouges for making PC boards
  • >50 MHz Oscilloscope
  • Frequency counter
  • Quality multimeter
  • Lab power supply
  • Calculator
  • Lab notebook
  • Collection of electronic junk
  • Parts catalogs
  • Capacitance meter
  • Test leads & socket boards
  • Nice-to-have tools
  • RF & audio generators, spice software & spectrum analyzer


Chapter 4


  • The nature of radio waves
  • Mechanical and LC electrical oscillators
  • Antenna and transmission line theory
  • Crystal set components
  • LC tuner
  • PN junction diode detectors
  • P-type and N-type semiconductors
  • Detection of AM signals
  • Homebuilding the parts for a crystal set
  • The Jamestown diode
  • The Caribou headphone
  • Revisiting Crystal Sets in 2006
  • Learning to troubleshoot
  • Selective tuning
  • Recreating Hertzs radio equipment
  • Transmitting and receiving as simply as possible
  • The 1880 ten-meter communicator
  • Proving that radio waves exist and arent just capacitive or magnetic coupling
  • Demonstrating standing waves to measure frequency
  • Building homebrew transistors
  • Bipolar transistors, PNP and NPN
  • Demonstrating voltage gain
  • The Boulder Rock Radio


Chapter 5


  • How to earn a license
  • The rules of the homebuilding game Whatever makes you happy!
  • Picking an HF band
  • Getting acquainted with the HF ham bands, 160 10 meters
  • Instant high quality HF communications
  • VHF/ UHF handheld transceivers
  • Building an antenna
  • Dipoles, regular and folded
  • Multi-band dipoles
  • 80 meters when you dont have room for a dipole
  • The curtain rod vertical
  • A multi-band vertical antenna
  • Lightning protection


Chapter 6


  • A single-band, crystal-controlled, QRP module
  • The transmitter mainframe
  • HF construction methods
  • Making your own PC boards
  • "Dead Bug" and "Gouged Board" construction
  • Superglue "Island Boards"
  • Coax jumpers
  • Shielded boxes
  • The complete QRP crystal-controlled transmitter
  • Transistor amplifiers and oscillators
  • How an amplifier becomes an oscillator
  • Class A and Class C amplifiers
  • Stabilizing the operating point, bypass caps and emitter resistors
  • Quartz crystals the key to frequency stability
  • The 40 meter QRP circuit
  • Oscillator and buffer
  • Inductors, RF transformers and impedance matching
  • Tapped toroid inductors
  • How to wind them (and mistakes you might make)
  • The final amplifier stages for the QRP
  • Tuned versus broadband - Use both for best results
  • Bifilar wound, broadband transformers
  • How to wind them (and how you might screw up)
  • Ferrite bead RF chokes, expensive RF power transistors, heat sinks & output connectors
  • Conquering inductors
  • Calculating resonance
  • Calibrating trimmer capacitors
  • Calculating turns on powdered iron and ferrite toroids
  • Chebyshev output low pass filters
  • Keying your QRP
  • MOSFET power transistors
  • A "spot switch" for the QRP


Chapter 7


  • A simple, direct-conversion receiver
  • A great first project for a new ham
  • Excellent sensitivity and good stability
  • Poor selectivity
  • Adding 700 Hz audio filtering
  • High pass and low pass filters
  • Cascaded bandpass filters increase selectivity
  • Operational amplifiers
  • Building with integrated circuits
  • AM broadcast filter
  • Getting rid of the image


Chapter 8


  • Line powered power supplies
  • Power supply safety features
  • Isolation, 3-conductor cords, fuses, switches, ratings
  • Supply performance and regulation
  • Rectification, ripple, chokes, capacitors, & bleeders
  • Zeners, linear regulators, switching regulators
  • A QRP regulated power supply
  • A battery power supply for the radio shack
  • Solar cell charging, low drop-out regulators
  • Battery powered shack lighting


Chapter 9


  • A straight key
  • An electronic bug
  • Building dummy loads
  • "T" type antenna coupler
  • A low pass filter
  • How to stay legal with a homebrew transmitter
  • Antenna and power relays
  • Homebrew QSL cards


Chapter 10


  • Drift is a big deal today
  • Low frequency VFOs drift less than high frequency VFOs
  • JFET transistors
  • The oscillator circuit
  • The buffer, final amplifier and output filter
  • The 50 secrets of avoiding drift
  • JFETs, single-side PC boards, cast metal box, multiple NPO caps, small variable caps, precision voltage regulation and more
  • Vernier tuning
  • Varactor tuning elements advantages and disadvantages
  • A precision power supply
  • A voltage doubler power supply for battery use
  • Square wave generator with a multivibrator
  • Squaring up the square wave
  • Charge pump, diode/ capacitor voltage doubler
  • Schottky diodes for efficiency
  • Temperature compensation methods
  • Positive coefficient capacitive trimmer compensation
  • How to adjust the compensator
  • Thermistor/ varactor temperature compensation


Chapter 11

Building a VFO for the higher bands (PMOs)

  • Old approaches that no longer work
  • Frequency multiplication
  • High frequency oscillators
  • PreMix Oscillator method of frequency translation
  • A VFO-controlled QRP module
  • Crystal oscillators are stable, arent they?
  • Crystal oscillator circuits
  • Butler oscillators and big crystals
  • Mixers, bipolar transistor and dual-gate MOSFET
  • Optimum drive requirements
  • Direction of tuning, drift error cancellation
  • Multistage filters and filter/amplifiers
  • The QRP final amplifier stages


Chapter 12


  • The basic features of a modern linear power amplifier
  • It looked easier in the Handbook
  • Linear "noise mode" operation
  • A tuned 50 watt class B amplifier
  • Ferrite balun transformers
  • An untuned, sort-of-linear, class B, amplifier
  • Keying the 50 watt transmitter
  • A linear Class AB amplifier, this time for sure
  • Single Sideband (SSB) needs a linear
  • Biasing without thermal runaway
  • Clamp diodes prevent runaway
  • Mechanical construction


Chapter 13


  • Building a receiver - an unusual adventure
  • Whats a reasonable goal?
  • An "adequate performance" HF communication receiver
  • Does it have to be so complicated?
  • Planning your receiver
  • Direct conversion versus superhetrodyne
  • Why not single conversion?
  • Start with a single-band, single-conversion superhetrodyne
  • How do modern digital receivers do it?
  • Receiver construction build with shielded modules connected by thin coax.
  • The 80 meter preselector
  • Reception on 80 meter and 160 meters is aided by a tuned transmatch
  • The Variable Frequency Oscillator
  • Mixer magic
  • Mixers will give you lots of static and howls and squeals
  • A practical homebrew mixer made from discrete parts its harder than it looks
  • Dual gate MOSFET mixers
  • Not all MOSFETS work equally well
  • Crystal ladder filters essential for CW
  • All 9.000 MHz crystals arent equal
  • Using the BFO oscillator to match crystals
  • Switch in filters with a rotary switch
  • The IF amplifier
  • Lessons learned from a dual-gate IF amplifier
  • The cascode amplifier strip - variable gain with constant Q
  • Automatic Gain Control (AGC) - not a luxury
  • The product detector
  • Nearly anything works at least a little
  • The AF amplifier a vital part of the signal dynamic range
  • Protecting your ears from strong signals
  • How Hi-Fi should it be?
  • Driving a speaker
  • HF converters for the other ham bands
  • Crystal oscillators
  • Bandswitching
  • Receiver power supplies
  • Use a linear regulator, not a switching regulator


Chapter 14


  • How old can radio technology be and still be used on the air today?
  • Why bother with vacuum tubes?
  • Glowing filaments, colored plasmas & Jules Verne glass envelopes
  • Power supplies for tubes
  • High voltage power supply safety
  • The old-tech QRP transmitter
  • Vacuum tube amplifiers
  • The three roles of the triode filament
  • RF sinewave oscillator
  • Quartz crystals
  • Triode and pentode oscillators
  • Old-tech voltage regulation big, crude, expensive, but beautiful
  • The travails of triode tubes
  • The oscillator and buffer
  • The final amplifier triodes chirp
  • The transmitter power supply
  • An inadequate supply from a 1935 radio
  • A good power supply made from cheap, modern, boring parts
  • How to check out junk power transformers
  • A complex but adequate supply made from ancient parts
  • It works! No one suspects its old and its a success on todays 40 meter band
  • An old-tech receiver
  • A super regenerative receiver made from ancient tubes
  • The power supply
  • Super-regen on the modern hambands
  • Lots of fun, but not up to modern QRM & QRPs - back to the drawing board!


Chapter 15


  • It cant be that hard! Want to bet?
  • The sideband generator how it works
  • The 9 MHz oscillator / amplifier
  • The audio amplifier
  • The balanced modulator
  • Building your own crystal ladder filter
  • Decoupling the power supply leads
  • Getting rid of RF feedback - RF filtering for all inputs
  • Tuning and testing
  • Using the generator for AM modulation and CW
  • Moving the 9 MHz SSB signal to a hamband
  • Move the SSB only once!
  • No wonder most ham rigs are tranceivers
  • Moving the 9 MHz signal to the difficult HF hambands
  • Move the VFO first, then mix it with the SSB 9 MHz.
  • Pick your oscillator and VFO frequencies carefully
  • Hearing your own VFO in the receiver
  • The hardest band 17 meters
  • Covering the widest band 10 meters
  • A linear sideband QRP, VFO-tuned module
  • All stages must be linear and low distortion
  • All gain stages should be broadband to prevent oscillation
  • Sometimes high pass filter output is needed & not the usual low pass
  • Checking out the generator
  • Driving a 50 watt linear amplifier


Chapter 16


  • Defining amplitude modulation
  • Modulating vacuum tube final amplifiers
  • Plate, screen & cathode modulation
  • A "collector modulator"
  • Converting a MOSFET keyer into a modulator
  • Generating AM with an SSB balanced modulator
  • Compensating for non-linearity
  • Compression by accident
  • You probably don't need to build a compressor
  • Ham TV - The old way
  • Fun with an ancient flying spot scanner TV camera


In conclusion:

Homebrew ham radio is never complete - when it works perfectly and does all the latest stuff, the hobby is over. Not likely. Long live homebuilding!

Thanks for reading my book.

73's Frank W. Harris, KØIYE

Last Updated on Sunday, 02 January 2011 17:21
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