By Frank W. Harris, KØIYE

Copyright © Frank W. Harris , 2003

REQUIRES ADOBE ACROBAT READER. 

• 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

• 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

• 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

• 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
• Recreating Hertz’s radio equipment
• Transmitting and receiving as simply as possible
• The 1880 ten-meter communicator
• Proving that radio waves exist and aren’t 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

• 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 don’t have room for a dipole
• The curtain rod vertical
• A multi-band vertical antenna
• Lightning protection

Chapter 6

BUILDING A QRP HOMEBREW

• 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

• 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

• 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

• 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

• 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

• 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, aren’t 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

• 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

• Building a receiver - an unusual adventure
• What’s 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 – it’s 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 aren’t equal
• Using the BFO oscillator to match crystals
• Switch in filters with a rotary switch
• The 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

• 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 it’s old and it’s a success on today’s 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!

• It can’t 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

• 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

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