The Type 103 was assembled from British components; patterned after the Fleming valve receiver. It covered from 200 to 600 meters amd used a carborundum detector with provision for an add-on cerusite detector. Although the carborundum detector was considerably less sensitive than the cerusite, it had an advantage of increased stability and wasn't easily disturbed by static, loud signals or vibrations.

The 103 was a very popular receiver. but by January of 1915 instructions were sent to technicians and operators for changes in the design resulting in a new model, nmely, the Type 107. The tuning circuits were completely overhauled, with a resulting coverage of 250 to 4,000 meters. By November of 1915, new orders detailed the reconstruction of the remaining Type 103 and Fleming valve tuners to allow reception of wavelengths up to 2,800 meters. After either type was altered according to the instructions, it became known as the Type 107-A, and is easily identified by a six-point, double-throw switch

103 tuner receiver. Click on image to enlarge. (Source: Jim Chew collection)
External detector for the type 103 receiver. It used a cup containing both carborundum and cerusite minerals. A brass loop was incorporated into the design which, when locked down to an operating table, made it difficult to put into one's pocket for their own use.  (Source: Kreuzer collection)
 Credits and References:

1) Jim Kreuzer`s chapter on American Marconi from his article
" Marconi -The Man and His Apparatus" , printed in the AWA Review vol. 9 1995

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Oct 13/20