ADAPTER FOR CONVERTING AN AM RADIO RECEIVER INTO A CITIZENS BAND CHANNEL 9 TRANSCEIVER

• US 3,665,310 A
• Filed: 06/18/1970
• Issued: 05/23/1972
• Est. Priority Date: 06/18/1970
• Status: Expired due to Term

• Current Assignee: Horace A. Tweed Jr
• Original Assignee: Horace A. Tweed Jr
• Inventors: Tweed, Horace A. Jr.
• Primary Examiner(s): Safourek, Benedict V.
• Application Number:
  US05/047,428
• Time in Patent Office: 705 Days
• Field of Search: 325/15,16,18,19,20,21,22,312,458,459,461 343/175,180
• US Class Current: 455/78
• CPC Class Codes: H04B 1/40 Circuits
• CPC Class Codes: H04B 1/54 using the same frequency for two directions of communication H04B1/44 takes precedence

Abstract

This adapter circuit comprises a microphone, a transmitter operating only at 27.065 MHz, and a down converter. It can be used with any conventional amplitude modulated (AM) radio set in an automobile without necessitating any physical change in the car radio. It is connected between the existing cable plug on the antenna and the antenna jack on the radio. During normal operation, signals received by the antenna are directly connected to the radio which is responsive only to signals having frequencies in the AM radio broadcast band. Emergency messages are transmitted at 27.065 MHz by actuating a switch that connects the antenna to the output of the transmitter, and talking into the microphone. Received signals having frequencies of 27.065 MHz are reproduced by down converting such signals to approximately 1,600 kHz signals that are coupled to the radio, the radio being manually tuned to the latter frequency.

Claims

1. Apparatus for electrical connection between the cable plug on the antenna and the antenna jack on the receiver of a conventional raDio for converting the latter to a channel 9 citizens band transceiver, comprising an enclosure, a connector jack on said enclosure similar to the antenna jack for connection to the cable plug, a connector plug on said enclosure similar to the cable plug for connection to the antenna jack, a microphone associated with said enclosure and adapted to convert a voice signal to an electrical output, said microphone having a switch thereon, a transmitter within said enclosure operating at 27.065 MHz and electrically connected to and responsive to the output of said microphone, a down converter within said enclosure and having an input and an output and adapted to convert an input signal having frequency of 27.065 MHz to an output signal having a prescribed frequency in the broadcast band of frequencies, first switch means in said enclosure electrically connected to said jack and to said plug and operative in one position to interconnect same whereby to couple said broadcast band signals from said antenna to said receiver, said first switch means in a second position electrically connecting said jack to the input of said down converter and connecting the output of the latter to said plug whereby said 27.065 MHz signals are heard on said radio when the latter is tuned to the prescribed frequency, and second switch means in said enclosure electrically connected to said jack and to the output of said transmitter and operative to electrically connect and disconnect same in response to the operation of said microphone switch whereby voice signals from said microphone are transmitted through said transmitter to said antenna.

2. Apparatus according to claim 1, wherein the radio is a conventional AM car radio located in an automobile having a battery and including means for selectively connecting said transmitter and down converter to the automobile battery.