PDF DOWNLOAD: Chapter 14
OLD-TECH VACUUM TUBE RADIO
- How old can radio technology be and still be used on the air today?
- Why bother with vacuum tubes?
– Glowing filaments, colored plasmas, and 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!