Radio-Telephone Aids Police (Sep, 1935)

Radio-Telephone Aids Police

MOTOR PATROLMEN, through the latest development in police communication, perfected by Bell Telephone laboratories, can now carry on a two-way conversation with headquarters without leaving their cars. The radio car transmitter weighs but 20 pounds, has a power of 5 watts, and is crystal controlled. The sound of the patrolman’s voice automatically puts the transmitter on the air.

  1. jayessell says: September 8, 201012:11 pm

    The VOX was probably replaced with ‘Press to Talk’ after
    an embarrassing incident involving pre-paying traffic fines.

  2. jayessell says: September 8, 201012:19 pm

    5 meter band approx 60Mhz.
    About double the frequency used by Citizens Band radios.

  3. Yoda says: September 8, 20106:14 pm

    Was there a technical reason for centering the transmitter in the trunk, instead of off to one side to minimize lost cargo space?
    This was obviously before cops carried everything but the kitchen sink in the trunk…

  4. Arglebarglefarglegleep says: September 8, 20108:45 pm

    I’d wager the transceiver in the center of the trunk was for the convenience of the technicians at Bell Labs. I’m guessing this wasn’t a production model radio but part of a Bell Labs press release.
    It’d be nice if they’d put a model number or product name on some of these articles.

    Is the officer wearing some kind of microphone setup on his chin? Or is that just an over sized chin strap for something on his head?

  5. Firebrand38 says: September 8, 20108:56 pm

    Arglebarglefarglegleep: Here is a better picture from a contemporary Popular Mechanics. You can see that the police officer is holding the phone in his right hand up to his ear.

  6. Arglebarglefarglegleep says: September 8, 20109:21 pm

    Ok, so it *is* a handset. Thanks for the link.

  7. Brian says: October 10, 20105:14 am

    There were several reasons for locating the transmitter in the trunk. Mobile radio transceivers of the 1930s were quite large, about the size of a briefcase but about twice as thick. There simply wasn’t room in the passenger compartment for them. These were not ‘under dash’ mountable by any stretch of the imagination! Also, these units were based on vacuum tubes which required B+ voltage supplies on the order of 200-300 volts. This high voltage was usually generated by a device called a dynamotor, which was a 12VDC motor and a multi-voltage generator wound on the same armature shaft. Dynamotors are naturally heavy and noisy- best put in the trunk. Last but not least, locating the transmitter as close as possible to a rear-bumper mounted antenna shortened the feedline and thus reduced power loss.

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