Chapter 10

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  • 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