RF Cafe Homepage
Windfreak Technologies Frequency Synthesizers - RF Cafe

PCB Directory (Manufacturers)

Innovative Power Products Cool Chip Thermal Dissipation - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low-priced products, all of which I created.

RF Cascade Workbook for Excel

RF & Electronics Symbols for Visio

RF & Electronics Symbols for Office

RF & Electronics Stencils for Visio

RF Workbench

T-Shirts, Mugs, Cups, Ball Caps, Mouse Pads

These Are Available for Free

Espresso Engineering Workbook™

Smith Chart™ for Excel

DIY Airplane Detector
May 1942 Popular Science

RF Cafe - May 1942 Popular Science CoverDuring World War II, Americans, Britains, Frenchmen, and other civilians were seriously engaged in helping to defend their homeland. Those who were not in the military gathered bottles, tin cans, tires, and clothing to use in the war effort. Others volunteered at the Red Cross, veterans' hospitals, and USO offices. Some stood guard at their nation's seashores and land borders, both as armed sentries and as troop and aircraft spotters. As part of the civil defense effort, listening devices were built to help detect the sound of approaching airplanes.

Homemade Plane Detector, May 1942 Popular Science (p72) - RF CafeIn patriotic tradition, magazines like Popular Science  published many articles to assist the population contribute. Here is a plan for a "Homemade Plane Detector." It used a horn "antenna" that fed into a 3-stage tube-based (1H5GT) amplifier + 1G4G headset driver circuit. You could build and power one today with a couple 1.5 V batteries - oh, and a 90 V and a 135 V battery.

See also Aircraft Detection Prior to the Invention of Radar

Exodus Advanced Communications Best in Class RF Amplifier SSPAs

LadyBug RF Power Sensors

Anritsu Test Equipment - RF Cafe