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About RF Cafe
1996 - 2022
BSEE - KB3UON
RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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October 1935 Short Wave Craft[Table of Contents]
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Short Wave Craft was published from 1930 through 1936. All copyrights are hereby acknowledged. See all articles from Short Wave Craft.
Antennas have been deployed in difficult environments using many ingenious methods over the years both by professionals and amateurs. The process typically involves first propelling a lightweight string or wire across and/or up to a supporting structure (a tower, tree, building, whatever) and then using that lead line to draw the antenna and its accompanying coaxial or twin lead cable into its final position. Sometimes simply tying a line to a rock and tossing it over a tree branch does the trick, but usually deployment requires a more powerful launch such as a a bow and arrow or even a model rocket. Many years ago a modeling magazine reported on a large radio controlled airplane that towed a lead line across a wide gulch in the mountains. Because the distance was so great, a pilot was stationed on each side of the gulch, each with a transmitter on the aircraft's frequency (72 MHz PCM was the modulation mode back then). Upon walkie-talkie signaling, the takeoff pilot switched off his transmitter and the landing pilot switch his on. The project was a success. This story reports on yet another deployment method that involved a bit if extra thinking to complete the project when the balloons refused to go all the way up the smoke stack. Here is a QST article titled "More on Balloon-Supported Antennas."
Balloons Raise S-W Antenna
Various stages in "balloon hoisted" aerial erection.
One of the most interesting problems ever to confront a radio construction engineer was recently encountered in Chicago Heights, Ill., when a new "RCA Terra Wave" transmitter was to be installed for transmitting police calls on ultra short waves, 30,100 kc., with call letters W9XGD.
A 175-foot brick smoke stack was handy for the purpose of supporting the aerial but as a professional steeple jack was not available at the time, the difficulty of getting the cable up through the 175-foot stack proved a poser.
It was finally decided that five balloons, each 16 inches in diameter, and filled with hydrogen, would raise an ordinary chalk line up through the stack. The balloons only rose to a height of 140 feet and after considering that the cooler draft of air inside the stack had contracted the gas in the balloons somewhat, it was decided to burn a few oil-soaked rags in the bottom of the stack. The warm air did the trick!
A heavier line was spliced onto the cord and allowed to run out through the top of the stack. How do you think the balloons were cut loose from the cord after a sufficiently heavy line was drawn up through the stack? Simple! A police sharp-shooter shot the balloons down and when the cord settled to earth, a heavier rope was pulled out through the top of the stack and finally a stranded copper wire cable was drawn into place, to serve as a permanent anchor for the police radio antenna. - Courtesy "Broadcast News."
Posted January 21, 2015