CONVERSION OF THE A MARK 6(B) MINESWEEPING GEAR TO A 30 CYCLE SOUND SOURCE
Abstract
The major change in the A Mk 6(b) gear required by the conversion was the attachment of an extension of the after end of the case, and the installation in the space thus provided of a synchronous motor coupled to the shaft of the dc motor. In this way driving or braking torque is supplied to hold the dc motor at constant speed. The frequency-stabilized ac power for the synchronous motor was provided by amplifying the output of a tuning-fork-controlled power supply. The push-pull amplifier with an output of 1.5 kw utilizes two 833-A tubes in class B operation. Propagation tests at long ranges and in deep water were carried out at Bermuda. The sound was received by the deep geophone (425 fathoms) of the US Navy Sofar Station. Intensity measurements were made out to a range of 140 mi. There were large dips in signal amplitude, but when these were not present the signal remained 20 db above background at this range. Doppler shifts of frequency could be measured to + or - 0.002 c. At speed greater than 4 knots the unit is not stable in the water at a 40-ft depth.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 10, 1953
- Accession Number
- AD0004926
Entities
People
- Harry Sonneman
- Henry C. Beck
Organizations
- Columbia University