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Equally unfortunate is that I have little information on GE's line of medium frequency and VHF AM equipment built prior to 1945, hence it is not covered here other than the 2-way item directly below.GE installed its first two-way AM equipment in 1934 for the Boston Police Department, operating in the 30 Megacycle band with an experimental license. From 1934 until the end of the 1930's, GE produced a 2-way mobile radio which was, depending on the year, a variation of the original 4GB1 transmitter shown below.By 1941, GE had already revised and superseded their initial FM equipment of 1938 at least four times, making it somewhat more compact and updating some of the circuitry. O.," for "manufacturing order." It should be noted that the first through third M. of GE FM equipment were actually manufactured by the James Millen Co. It is unknown what the Millen-made equipment looked like or the model designations, but it was a small quantity order.Following the E-1 Series, the next generation of equipment would have typical model numbers of 4RMD and 4TMD, referring to the receiver and transmitter respectively.Link and Daniel Noble for the Connecticut State Police proved its superiority over the older low frequency one-way AM broadcasts and AM in general.From that point on, all major manufacturers switched emphasis to VHF FM products and generally introduced no new-design AM equipment from that point onward. This is not to say that AM equipment was not still being sold, just that purchasers were still buying models and designs dating from 1940, more or less.This equipment was "Two frequency duplex," in other words, transmitter and receiver operated on separate frequencies spaced far enough apart that the transmitter could be on the air at the same time the receiver was still listening.Separate antennas were used, the receiving one being either the wire concealed in the "tar top" car roof shown below, or a more modern "whip" on the front fender.
Note the huge dynamotor which GE referred to as an advantage because it offered "continuous duty transmitter operation." It should be noted that equipment like this placed a huge drain on 6 Volt car batteries and electrical systems, often requiring changing of batteries at the end of each shift!
GE had applied to the FCC for an experimental license for FM operation on 49 MHz which was granted on August 3, 1938. FM (at 15 k Hz /- deviation) on September 28-29, 1939, with Maj.
Edwin Armstrong in attendance, for the FCC Emergency Service administration.
Link's first FM equipment consisted of a modified 8UA VHF AM receiver and 15UBX AM transmitter from 1938.
GE was one of the few manufacturers to respect the Armstrong's patents on FM, and took out licenses to use that system, as did Link.
The Leece-Neville "flux-cutter" alternator was marketed at the end of the war as a solution to the issue, allowing high current output even at idle.