ABSTRACTS OF TECHNICAL ARTICLES 767 



with frequency define the performance of the unit. Crystal units are available 

 in the frequency range from about 1,000 cycles to over 100 Mc. Their resist- 

 ance range may vary from less than 10 ohms to over 150,000 ohms, the 

 inductance from a few millihenries to nearly 100,000 henries and the capaci- 

 tances from about 0.001 uuf to 50 uuf. Modern test oscillators, with fre- 

 quency and capacitance measuring apparatus as auxiliary equipment, will 

 measure these quantities with accuracies sufficient to meet present needs. 

 The transmission measuring circuit also is described and is proposed as the 

 standard reference circuit for comparison with the test oscillators. 



Local Wire Television Networks* C. N. Nebel^ Elec. Engg., v. 70, pp. 

 130-135, Feb., 1951. 



Abstract — A new local video distribution system has been developed 

 which provides equalization and amplification of signals transmitted over 

 links between television studios, transmitters, coaxial cables, and micro- 

 wave networks. The equipment consists of a transmitting terminal, an inter- 

 mediate repeater with cable equalizers, and a receiving terminal. 



Effect of Heat Treatment on the Electrical Properties of Germanium* H. 

 C. TheuererI and J. H. Scaff^ //. Metals, v. 191, pp. 59-63, Jan., 1951. 



Abstract — Germanium may be reversibly converted from n to p type by 

 heat treatment. Data for the conversion and the associated changes in re- 

 sistivity are given and the results are interpreted in terms of changes in the 

 donor-acceptor balance. 



Aging of Black Neoprene Jackets* G. N. Vacca^ R. H. Erickson^, and 

 C. V. LuNDBERG^ References. Ind. & Engg. Chem., v. 43, pp. 443-446, 

 Feb., 1951. 



Abstract — Considerable loss in elongation of black neoprene jackets re- 

 moved from wires which had been in outdoor service for comparatively 

 short periods of time raised the question of the life expectancy of such cover- 

 ings. Information available did not permit estimation of service life and a 

 program of testing was undertaken to provide this information. 



Accelerated aging tests corroborated by later field tests indicated that 

 early loss of considerable elongation is not indicative of early failure in 

 service as loss of elongation levels off and changes much more slowly on 

 continued exposure. 



Accelerated aging in air at temperatures up to 100° C. gave results most 

 comparable with outdoor aging as regards loss of elongation. As a result of 

 this work, it can be predicted with a good degree of reliability that a black 

 neoprene jacket will remain serviceable for periods of the order of 20 years. 



* A reprint of this article may be obtained on request. 

 1 B. T. L. 



