Chapter 13

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  • 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
A JFET alternative mixer

  • 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

Lessons learned from a dual-gate IF amplifier
The cascode amplifier strip – variable gain with constant Q

  • Automatic Gain Control (AGC) – not a luxury7.
  • 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
Band switching

  • Receiver power supplies

Use a linear regulator, not a switching regulator