US2513796A

US2513796A - Switch and tuning device for radio transceivers

Info

Publication number: US2513796A
Application number: US620347A
Authority: US
Inventors: De Witt R Goddard
Original assignee: RCA Corp
Current assignee: RCA Corp
Priority date: 1945-10-04
Filing date: 1945-10-04
Publication date: 1950-07-04
Anticipated expiration: 1967-07-04

Description

y 1950 DE WlTT R. GODDARD 2,513,796

SWITCH AND TUNING DEVICE FOR RADIO mmnscmvms Filed Oct. 4, 1945 INVENTOR 05 W77 ooa/wa.

ATTORNEY Patented July 4, 1950 SWITCH AND TUNING DEVICE FOR RADIO TRANSCEIVERS De Witt R. Goddard, Riverhead, N. Y., assignor to Radio Corporation of America, a corporation of Delaware Application October 4, 1945, Serial No. 620,347

4 Claims. 1

This invention relates to means for tuning a transceiver, andrfor switching the. circuits thereof between receiving. and transmitting conditions.

In two-way'ra'dio telephone sets it is customary to provide a push-to-ta lk key or button wherebythe circuits" of the transceiver may be altered and at the same'time the frequency of the oscillator" maybe shiitedto" that of the assigned outgoingcarrier' wave.

It is' an object of my invention to provide a simple mechanical sliding button to substitute' for'the'prior art type of push to talk button. The present invention provides a novel sliding device having the unit-control function of shifting the frequency of an oscillator in a transceiver so as tocondition the oscillator for producing the carrier wave when transmitting, and of re-tunin'g theoscillator for reception so as to producesuper-regeneration, the sliding device being simultaneously effective in performing a switching operation;

This application deals with novel means for switching the circuit connections of high frequency transmitters and receivers for operation at one time asa transmitter and at another time as a receiver, such means being combined with a tuning device which is readily adjusted to any desired frequency for reception while being instantly shiftable to another frequency suitable for transmission;

My invention will now be'described in more detail, reference being made to the accompanying drawing in which? Fig.1 showsla view of the switch and tuning device as it appears with the instrument cover removed; A

Fig. Z'shows another viewof. the same arrangement but with the switch and tuning deviceshifted to the talk? position; and

Fig. 3 shows in perspective the mounting for a short-circuited' tuning ring which is variably positionable in relation tothe tank circuit winding of an antenna transformer.

Since like parts are given the same reference numerals indifferent figures of the drawing, reference may be made from one figure to .another according. to the needs of the description to follow, for best illustrating, the invention.

The complete transceiverrunit,except for the antenna, earphones. and battery, is assembled in compact form within a case I. At. one end of this case is a receptacle 2 into which an antenna may be plugged; The terminals of the receptacl'e are connectedto. a loop 3" which. consti 2 tutes one inductive member of an antenna transformer. The end-of this loop is in:coupling,relation to a tankecircuit winding 5. The terminals of Winding 5 are suitably connected between the anode and grid of an oscillator tube (not shown) The other components of the oscillator circuit are conventional anddo not constitute essentialparts I of theinstant invention.

A tuning loop 4 is mounted in coupling relation to the tank coil 5. The mounting is-by means of a swiveledinsulating block 6. A pivot post 1 for the block 6- is firmly affixed to the casing of thetransceiver.- Around the post i I preferably position acoiled spring 8, one end of which is attached at the top of. the post and the other. end is secured to the insulating block 6 at a point intermediate its two ends. The tension on the spring 8 is arranged to swing the block 6 counterclockwise and to bring the tuning coil 4 as close to the tank coil 51 as may be permitted by one or the other of two stops 9 and it Stop 9 is at the-end of a push rod H which isunder. control of. a.s1iding button l2. to be used as a 'push-to-talk button.

The other stop I0 is at one end of a push-rod I3 which. is. arranged to: be actuated by a rotatable tuning knob l4. Thetuning knob is shown dottedbecause it-is outside of the case, but it is swiveled. on a. shaft which also carries a disc l5 within the case. An eccentric pin 16 on the disc l5- constitutes. a pivot. bearing for one end of the push-rod l3. Concentric with the. disc l5 and mounted thereon is another. pin H which serves as a stop to prevent over-travel of the push-rod l3 beyond a desirable limit correspond-. ing to the low frequency endofithe tuning range forthe oscillator as used" for super-regenerative The rod ll carries two slidling contact plates I 20 and 21; which serve to interconnect certain switch terminals off'a double-pole-double-throw switch. The switching functions performed in order to condition the normally receptive circuit for transmission involve closing. a circuit from contact 22 to contact 23-, and also transferring the connection of contact from contact 25to contact 26'; The pushbutton l2 performs this These openings in the v of a spring 3i.

service whenever the thumb of the operator drives this button to the right. Fig. 2 shows the button I2 and associated rod H moved to the right, which is the talking position.

In a preferred arrangement of the push-button control for the switch bar H the button 12 is mounted on a plate which slips forward and back on the outside of an edge wall of the case cover. Inside of this wall is a retaining strip which is fastened to the outside plate by means of two

screws

21 and 28. These screws are fitted with nuts on the inside in order to hold the plates together and allow a free sliding movement of the push-button. Screw 21 is longer, however, than screw 28 in order that it may serve to engage a pin 30 on the push-rod ll. When operating the push-button E2, the push rod H is moved to the right in opposition to the tension Upon releasing the push-button l2, the push-rod is restored by the tension of the spring 3| to the position for receiving.

In the operation of my tuning means as above described, the tuning knob I4 is turned to the correct position for tuning the oscillator circuit to such frequency as will produce super-regenerative reception. This tuning operation sets the short-circuited loop 4 in proper position, to which it will be automatically returned after each release of the push-to-talk button. The displacement of the short-circuited loop 4 by operation of the push-button is provided by the swinging of its insulation mounting block 6 to an extreme position, which is determinedby the striking of a pin 32 against the partition wall I9. Pin 32 may be the same pin which holds the spring 3|, the other end of the spring being mounted on a stationary post afiixed to the chassis.

It should be noted that the means provided for switching from listening to ftalking conditions is combined with the adjustment of the shortcircuited loop 4 in a very simple but novel manner. It is well known that a short-circuited loop may be used in this fashion tovary the frequency of an oscillator. V

The range of, frequencies available for tuning the receiver is that which is obtained bythe movement of the short-circuited loop 4 under spring tension between two limits. quency of the oscillator is obtained when the loop 4 is nearest to the tank coil 5. This position is determined by the stop 9 on the end of the push rod H when the latter is held in normal position by the tension of spring 3|. The lowest frequency to be used for reception is obtained when the insulating block 6 is rotated clockwise by the rod l3 until the latter butts against the pin l! at for producing the desiredtransmittingcarrier wave.

One drawback of the pastwhich has been overcome by the adoption of my. invention is that there is no longer any tendency for two transceivers in communication to"walk the frequency up. This difficulty was caused by retuning the transceiver each time it started to receive. Then, upon transmitting, the oscillator delivered a higher frequency than before, due in part to the higher anode voltage applied to the oscillator when talking, and eventually the carrier wave passed out of the assigned communication channel. In other words, each time a shift was made The highest frefrom receiving to talking the previous adjustments were lost, and attempts to restore the assigned frequencies were not always successful. With the aid of the invention herein disclosed, the carrier frequency remains fixed for two transceivers in communication, andthere is no tendency for tuning adjustments to be displaced when operating the push button.

In practice my system will allow a plurality of transceivers to be adjusted so that they all transmit on a predetermined assigned frequency. These transceivers may then be operated independently, maintaining communication with each other without deviating from the original frequency.

What is claimed is:

1. In a radio transceiver, a transformer coil in a'tank circuit which is tunable to a radio frequency carrier wave, a closed'loop disposed in reactive coupling relation to said coil, pivoted means for supporting said loop, a resilient member for urging said pivoted means and its loop toward the tank circuit, two push-rods effective to press against said pivoted means in opposition to the force of said resilient member, a tuning device manipulatably operable to setone of said push-rods, thereby to fix the degree of coupling between said coil and said closed loop suitably for obtaining a super-regenerative receiving condition in said transceiver, and a sliding mechanism operable upon the other of said push-rods to cause that amount of diminution in the degree of coupling, whereby the tank circuit is tuned to the frequency of the carrier wave which is to be transmitted.

2. In a device according to claim 1 a plurality of stationary and movable switch components constituting means for conditioning the circuits of said radio transceiver either to receive or to transmit, the movableswitch components being mounted on that one of the push-rods which. is operable by said sliding mechanism.

3. In a two way radio apparatus, a sliding operating member, a spring tensioned pivoted arm disposed so as to be actuated by an end of said member, movable switch contact means carried by said member, a movable tuning loop located on an end of said arm, a tuning coil inductively coupled to said loop, fixed contact means for engaging said movable contact means, said member acting to shift said arm to thereby vary the tuning of said apparatus, resilient means secured to said member and acting to oppose the, move ment of said member, and a transmit-receive system controlled by said contact means, said system including an oscillator whose tank circuit includes said tuning coil.

4. In a two-way radio apparatus, the combin a tion with a manipulatable sliding mechanism of switching means operable by suchmechanism to condition the circuits of said apparatus for transmitting a modulated carrier wave of predetermined frequency, a short-circuited loop coupling member inductively coupled to a tank circuit which is one Of the components of said radio apparatus, said member being adjustably mount,- ed with respect to said tank circuit and being adjustable to a normal position relative thereto which permits of super-regenerative reception of signals having the frequency of said carrier wave, means operable by said mechanism for adjusting said member relatively to said tank circuit to a position which fixes the frequency of the transmitted carrier wave, and resilient means for biasing said member toward said normal position, sa d res li nt means operating in response to 5 2 release of said mechanism to restore said member Number to said normal position. 2,153,205 DE WITT R. GODDARD. 2,187,340 2,288,214 REFERENCES CITED 5 ,41 ,794 The following references are of record in the file of this patent:

Number UNITED STATES PATENTS 470,366 Number Name Date 10 512,121 2,018,569 Pettengill et a1 Oct. 22, 1935 550,774 2,126,868 Brown Aug. 16,1938

Name Date Park Apr. 4, 1939 Wilhelm Jan. 16, 1940 Summers June 30, 1942 Crosby Mar. 4, 1947 FOREIGN PATENTS Country Date Great Britain Aug. 13, 1937 Great Britain Aug. 29, 1939 Great Britain Jan. 25, 1943