Marconi model 24 decremeter
date: label: date made
content: 1915
name: label: maker
content: Marconi Wireless Telegraph Co. of America
notes: label: Description (Brief)
content: Marked: "Marconi Wireless Telegraph Co. of America / Decremeter / Type No. 24 / Cat. No. / Serial No. 6 / Range: Wavelengths / 250 meters to 850 meters / Date: 2-1-15". Marconi model 24 decremeter with coil. Wooden case (lid missing) with glass faced meter and sweep control mounted on plastic plate. Loop coil stamped "Decremeter / No. 24" with leather-insulated cord and 2-pin connector stored inside unit. Unit designed to measure wavelength, frequency, and decrement of oscillations in wireless telegraph circuits. Operation depends on adjusting constants to resonance with circuits being measured. Unit consists of a variable condenser that carries and indicator or pointer. The indicator moves over a scale graduated in degrees, wavelengths, decrements, and capacity values. A Roller-Smith Company hot wire galvanometer and an inductance are placed in series with this condenser that has a range of .00025 to .003 MFD.
label: Description (Brief)
content: The inductance coil is 9" in diameter, and is connected to the variable condenser by means of a large flexible conductor. The value of the inductance is fixed for a given instrument and depends on the range of wavelength of the instrument. By varying the capacity of the condenser the natural period of the circuit is varied so that the circuit can be adjusted to resonance for any wavelength within its range. The wavelengths corresponding to the different values of the condenser are marked on the scale. Capacity values are indicated by "K", value of the decrement is indicated by "S".
label: Description (Brief)
content: Reference: Description of and Directions for Operating the Marconi Decremeter, No. 24, March 12, 1915, Clark Collection, CWC 74-361A.
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.321491
label: accession number
content: 241556
label: catalog number
content: 321491
objectType: label: Object Name
content: decremeter
physicalDescription: label: Measurements
content: overall: 10 1/32 in x 19 in x 6 1/4 in; 25.4635 cm x 48.26 cm x 15.875 cm