Kolster type D Decremeter
date: label: date made
content: c 1918
label: date made
content: ca 1918
name: label: maker
content: Cardwell Manufacturing Co.
notes: label: Description (Brief)
content: Marked on nameplate: "Kolster Decremeter / Type D / Serial No. 290 / Manufactured for / John Firth & Co., Inc. / 81 New Street / New York / by / Allen D. Cardwell / British Patent 3478 of 1914; French Patent 469004 of 1914; U.S. Patent Feb. 27, 1912. / Range: 75 to 3000 meters". Instrument was designed for measuring wavelength and logarithmic decrement of radio circuits. The type "D" is essentially a wavemeter consisting of a variable condenser, four inductance coils, and a sensitive Weston Model 425 thermo-galvanometer, the readings of which are proportional to the square of the current passing though it. A crystal detector and head telephone are provided, and wave-length measurements may be made with the crystal and telephone receiver, or with the hot wire meter. A buzzer is included that may be used as a transmitter for calibrating purposes. For measurement of wave length four scales are provided, each used with a specific coil (coils housed in lid). Beneath the condenser knob is a scale which is marked off to the right and to the left of the zero line from 0 to 0.30. These scale divisions represent the sum of the logarithmic decrement of the transmitter and of the decremeter, lambda 1 plus lambda 2, lambda 1 being the decrement of the transmitter under test and lambda 2 the decrement of the instrument. Reference: Description and Instructions for the Kolster Decremeter, type D, 1917. Clark Collection: CWC 74-354A.
label: Location
content: Currently not on view
setName: label: See more items in
content: Work and Industry: Electricity
creditLine: label: Credit Line
content: from Franklin Wingard
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: EM.321280
label: catalog number
content: 321280
label: accession number
content: 241556
objectType: label: Object Name
content: decremeter
physicalDescription: label: Measurements
content: overall: 9 1/4 in x 10 in x 10 in; 23.495 cm x 25.4 cm x 25.4 cm