The point-contact crystal detector became vital for microwave radio systems, since available vacuum tube devices could not serve as detectors above about 4000 MHz; advanced radar systems relied on the fast response of crystal detectors.
32.
The point-contact crystal detector became vital for microwave radio systems, since available vacuum tube devices could not serve as detectors above about 4000 MHz; advanced radar systems relied on the fast response of crystal detectors.
33.
Because of its relatively long half-life and emission of low-energy photons which can be detected by gamma-counter crystal detectors, I-125 is a preferred isotope for tagging antibodies in radioimmunoassay and other gamma-counting procedures involving proteins outside the body.
34.
His interests focused on the point-contact crystal detector ( cat's whisker detector ), which was used as a demodulator in the first early radio receivers, crystal radios, before powered vacuum tube radios were developed in World War 1.
35.
Lovell had attempted a solution using two dipoles in front of a common parabolic reflector, separated by a metal disk, but found that enough signal leaked through to cause the crystal detectors in the receivers to burn out.
36.
The crystal detector worsened the problem, because it has relatively low Q . In many circuits, the selectivity was improved by connecting the detector and earphone circuit to a tap across only a fraction of the coil's turns.
37.
Such variability, bordering on what seemed the mystical, plagued the early history of crystal detectors and caused many of the vacuum tube experts of a later generation to regard the art of crystal rectification as being close to disreputable.
38.
This troublesome device was superseded by thermionic diodes ( vacuum tubes ) by the 1920s, but after high purity semiconductor materials became available, the crystal detector returned to dominant use with the advent, in the 1950s, of inexpensive fixed-germanium diodes.
39.
This development was slowed by the German electronic's industry's decision to stop researching microwaves shortly before " Rotterdam Ger�t " literally fell from the sky, and a lack of suitable crystal detectors that were key to the British receiver designs.
40.
Other radio detectors invented for wireless telegraphy, such as the Fleming valve ( 1904 ) and the crystal detector ( 1906 ) also proved able to rectify AM signals, so the technological hurdle was generating AM waves; receiving them was not a problem.
