xtal

CRYSTAL RADIOS

I work on vintage radios as a counterpoint to my professional career as a Field Applications Engineer for a major semiconductor company, as in a billion transistors under your thumb nail. It's refreshing to work on devices where you can actually see the individual components. In between high-end ommunication-receiver restorations, I build crystal sets.

A Crystal-Set Circuit Tutorial:

CRYSTAL SET DESIGN 102

Crystal radio Schematic

Coils

Coils can make or break a crystal set. Here are some thoughts on their design:

One of the weak links in many sets is the earphones.
Headsets

Sound-Powered Telephone Spotter's Guide

The Search for Steel Galena

You can mount your own mineral crystals for use as detectors:
Mounting Crystals

A look at some vintage detectors:
TWO WIRELESS DETECTORS

Perikon Detector

Crystal-Set Projects:
	Build a Pretty Good Crystal Set The PGXS Mark II
People building their own PGXS's at the Radio Technology Museum
	Make Your PGXS Double-tuned Build a second coil-capacator assembly on a separate base. Connect it to your antenna and ground, and place it beside your PGXS. Tune the original set to minimum capacity, and bring the two coils together, end to end, as close as possible. Search for stations using the coil taps and capacitor on the "primary," The front end. Then pull the coils apart, and retune the secondary. You'll be amazed. Crystalsets don't get a whole lot better than this.
A minature crystal set for urban areas: The City Mouse
	SkyWaves High-Performance Crystal Set
A simple but effective SINGLE-TUNED SET that rejects short-wave signals.
	Now you'll need a detector stand. Here's one you can build: Detector Stand
An experimental SHORT-WAVE CRYSTAL SET
WWI German Field Receiver
	WWI German xtal set in the Signal Corps Museum. This radio is associated with Edwin Armstrong, who's unit in France, 1918, did evaluations of captured equipment.. Signal Corps blueprints available here: http://users.erols.com/oldradio/eha13.htm Detector Closeup

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