Tuesday, December 14, 2010
A Great Book about Amateur Radio
The World of Ham Radio, 1901-1950: A Social History
by Richard A. Barlett
During the first fifty years of the twentieth century, ham radio went from being an experiment to virtually an art form. Because of the few government restrictions and the low monetary investment required, the concept of ham radio appealed to various people. More than just a simple hobby, however, ham radio required its operators to understand radio theory, be able to trace a schematic and know how to build a transmitter and receiver with whatever material they might have available. With the advent of World War II and the increased need for cutting-edge communications, the United States government drew upon the considerable knowledge and skill of these amateur ham radio operators, validating the fact that ham radio was here to stay.
This book explores the history of ham radio operators, emphasizing their social history and their many contributions to the technological development of worldwide communications. It traces the concept of relays, including the American Radio Relay League, from contacts as close as 25 miles apart to operators anywhere in the world. The book highlights the part played by ham radio in many of the headlined events of the half century, especially exploration and aviation "firsts". The ways in which these primarily amateur operators assisted in times of disaster including such events as the sinking of the Titanic and the 1937 Ohio River flood, are also examined.
HOW TO READ PROPAGATION NUMBERS
The A index [ LOW is GOOD ]
- 1 to 6 is BEST
- 7 to 9 is OK
- 11 or more is BAD
Represents the overall geomagnetic condition of the ionosphere ("Ap" if averaged from the Kp-Index) (an average of the eight 3-hour K-Indices) ('A' referring to amplitude) over a given 24 hour period, ranging (linearly) typically from 1-100 but theoretically up to 400.
A lower A-Index generally suggests better propagation on the 10, 12, 15, 17, & 20 Meter Bands; a low & steady Ap-Index generally suggest good propagation on the 30, 40, 60, 80, & 160 Meter Bands.
SFI index [ HIGH is GOOD ]
- 70 NOT GOOD
- 80 GOOD
- 90 BETTER
- 100+ BEST
The measure of total radio emissions from the sun at 10.7cm (2800 MHz), on a scale of 60 (no sunspots) to 300, generally corresponding to the sunspot level, but being too low in energy to cause ionization, not related to the ionization level of the Ionosphere.
Higher Solar Flux generally suggests better propagation on the 10, 12, 15, 17, & 20 Meter Bands; Solar Flux rarely affects the 30, 40, 60, 80, & 160 Meter Bands.
K index [ LOW is GOOD ]
- 0 or 1 is BEST
- 2 is OK
- 3 or more is BAD
- 5 is VERY VERY BAD
The overall geomagnetic condition of the ionosphere ("Kp" if averaged over the planet) over the past 3 hours, measured by 13 magnetometers between 46 & 63 degrees of latitude, and ranging quasi-logarithmically from 0-9. Designed to detect solar particle radiation by its magnetic effect. A higher K-index generally means worse HF conditions.
A lower K-Index generally suggests better propagation on the 10, 12, 15, 17, & 20 Meter Bands; a low & steady Kp-Index generally suggest good propagation on the 30, 40, 60, 80, & 160 Meter Bands.
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