US1670149A - Radio receiving system - Google Patents

Description

May 15, 1928. 1,670,149

C. W. HANSEN RADIO RECEIVING SYSTEM Filed Dec. 26, 1925 2 h ets-Sheet 1 C. W. HANSEN RADIO RECEIVING SYSTEM May 15, 1928,

2 Sheets-Sheet 2 @rzbfbvz fl flzsaz Filed Dec. 26, 1925 Patented May 15, 1928.

UNITED STATES.

PATENT, OFFICE.

CHRISTIAN W. HANSEN, OF CHICAGO, ILLINOIS, ASSIGNOR TO ZENITH RADIO COR- PORATION, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

RADIO RECEIVING SYSTEM.

Ap lication filed December as, 1925. Serial No. 77,859.

My invention relates to receiving sets employed in systems of radio communication that include thermionic valves and volume control devices, preferably rheostats in 011'- cuit between the heating filaments of the valves and the source of filament heating current. One notespecially skilled in the use of radio receiving sets is apt to believe that his set is turned off when the rheostat or other volume controlling element is adjusted to cause the reception substantially to cease, yet without actually breaking the A battery circuit with the result that the battery is often wasted.

My invention, in accordance with one of its characteristics, resides in the provision of mechanism for automatically completing the throw of the rheostat arm or other volume regulating element in case it is brought to rest before fully reaching volume eifacing position.

In radio receiving systems, one rheostat is frequently made common to the filaments of all of the radio frequency amplifying thermionic valves of the set, the heating filament of the detector thermionic valve having another resistance, also in circuit with the same A battery, which is not governed by the rheostat that pertains to the other valves. I, therefore, also desirably provide a switch through which the A battery supplies its current to the filaments of all of the valves, this switch remaining closed throughout the normally effective range of operation of the rheostat and being opened when the rheostat is adjusted to substantially efl'ace the reception. The switch is of particular service in disconnecting the filament of the detector valve and also supplements the function of the automatic device for discontinuing the flow of current from the A. battery through the heating filaments of the amplifying valves as well, an advantageous feature in the event that the rheostat arm happens to remain in engagement with the rheostat resistance.

I will explain my invention more fully by reference to the accompanying drawings in which Fig. 1 is a diagrammatic View of one receiving system equipped in accordance with the preferred embodiment of the invention; Fig. 2 is a front view of the preferred form of rheostat and automatic device for positively opening the. circuit of the A battery; Fig. 3 is a sectional View on line 33 of Fig. 2; Fig. 4 is a sectional view on line 44 of Fig. 2; and Fig. 5 is a persp'ec:

tive view illustrating the rheostat arm and tennae and not with short antennae, and the grounded primary coupler transformer winding 3. The stationary secondary winding 4: of the vario coupler is in series with a rotatively adjustable winding 5. The variable secondary tuning condenser 6 is in shunt relation to the coils 1 and 5, taken together, being thus also traversed by radio frequency current. The elements 4, 5 and 6 are thus in a resonant circuit whose terminals are connected with the input electrode or grid 7 and the heatin filament 8 of a. radio frequency amplifying thermionic valve 9. Said valve also includes the output plate or electrode 10. The output circuit which includes this electrode also contains a stationary primary radio frequency transformer winding 11, a rotatively adjustable windin 12 in series with the winding 11, and the battery 13 in series with. both windings 11 and 12. The stationary radio frequency transformer secondary winding 14 is in inductive relation to the windings 11 and 12. The secondary 14 is shunted by a variable secondary tuning condenser 15.

There is thus a second resonant circuit in cascade relation to the first and whose terminals are connected with the input electrode ,or grid 16 and the heating filament 17 of a radio frequency amplifying thermionic valve 18. Said valve 18 also includes the winding 20, and the aforesaid B battery.

The stationary radio frequency transformer secondary winding 22 is in inductive relation to the windings 20 and 21. The secondary 22 is shunted by a variable secondary tuning condenser 23. i There is thus a third resonant circuit in cascade relation to the other two and whose terminals are connected with the input electrode or grid 24 and the heating filament 25 of a radlo frequency amplifying thermionic valve 26.' Saidfvalve 26 also includes the output plate or electrode 27. The output circuit which includes this electrode 27 also contains a stationary primary radio frequency transformer winding 28, a rotatively.

adjustable winding 29 'in series. with the winding 28, and the B battery 13. The stationary radio. frequency transformer secondary winding 30 is in inductive relation to the'windings 28 and 29. The secondary 30 is shunted by a variable secondary tuning condenser 31. i

There is thus a fourth resonant circuit in cascade relation tothe other three and whose terminals are connected with the input electrode or grid 32 and the heating filament 33 ofa thermionic detector valve, 34, this resonant circuit being-connected with the grid 32 by way of the usual condenser 35 and the high resistance leakage path 36 in shunt to this condenser. Said valve 34 also includes the output plate or electrode 37. The output circuit which includes this elect-rode 37 supplies the telephone receiver 38 with audio frequency current, the output circuit containing the electrode 37 and receiver 38 also containing a portion of the B battery. The telephone receiver is shunted by th usual by-pass condenser 39. p

I have shown a cascade of four radio frequency tuning circuits but the invention may be practiced with one radio frequency tuning circuit. All of the adjustable elements, hitherto described, of the receiving circuit, may, if desired, be simultaneously regulated by unitary adjusting means in accordance with well-known practice.

The heating filaments of the, radio frequency amplifying thermionic valves 9, 18 and 26 and the heating filament of the detector thermionic valve 34 are supplied with heating current from the A battery 40, or other source of current. The filaments of the valves 9, 18 and 26 are supplied through the rheostat resistance 41. The filament of the valve 34 is supplied through the resistance 42. One extremity of the rheostat resistance 41 is permanently connected with the filaments to which it pertains. The contacting switch arm 43 of the rheostat sweeps over the resistance 41 between the connected extremity of the resistance and the free or unconnected extremity of the resistance in effecting the filament adjustment, a stop 44 being generally employed to retain a minimum amount of the resistance 41 in circuit when the receiving set is functioning. When the rheostat arm 43 is swung to the anism is inclusive of a disc45 that is fixed with respect to the shaft 46 that carries the rheostat arm, this shaft being journaled in a bearing 4( which is carried by the support 48 for the rheostat resistance. Theshaft is provided with the usual operating knob or handle 49. The disc 45 is mechanically coupled with thearm 43 by.virtue of the shaft 46 passing through the arm and disc and the tail 50 upon the arm that passes into Y an opening 51 in the disc. This disc isconstituted a cam disc by being provided with a peripheral notch 52. A spring 53 is anchoreo. at one end upon the resistance support 48 and has a kinked portion 54. The spring'is so located that the kink 54 therein Wlll enter the notch 52 when the rheostat arm is in engagement with the concludingportion of the low volume extremity of the rheostat resistance, the spring then functioning to complete the resistance excluding motion of the rheostat arm preferably to an extent which will disengage the rheostat armfrom the resistance, though the invention need not be thus limited as will presently appear. The spring 53, in addition to performing its mechanical function, desirably alsoconstitutes a contacting member of a switch in which vevent is is provided with a contacting point 55 at its free end. The contact 56, which is complemental to the contact-55, is desirably provided upon the free end of another spring 57 which is also carried by the resistance support 48. When the rheostat arm is in the portion of its range of movement in which the filament current is adjustable thereby, the unnotched portion of the disc engages the kinked portion 54 of the spring 53 to maintain the contacts 55 and 56 in engagement, the circuit of the A battery serially including these contacts that are thus traversed by the A battery current flowing to the filaments of all of the valves. When the rheostat is out of circuit and the kinked portion 54 of the spring 53 consequently enters the notch 52, the contact 55 is witharm 43 has not been moved entirely out of connection with the resistance 41.

Changes may be made without departing from the invention.

Having thus described my invention, I claim:

1. A radio receiving system including a radio frequency amplifying thermionic valve having input and output electrodes and a heating element in a heating circuit; a thermionic detector valve also having input and output electrodes and a heating element in a heating circuit; a source of current for inclusion in circuit with each of said heating elements; a rheostat including a resistance and a switch arm connectible with different portions of the resistance to vary the amount thereof that is included in circuit, said switch arm and the portion of the resistance selected thereby being serially in the heating circuit of said radio frequency amplifying valve; and means controlled by said switch arm for opening said heating circuits and rendered operative by said switch arm when said arm is near the free extremity of said resistance.

2. A radio receiving system including a radio frequency amplifying thermionic valve having input and output electrodes and a heating element in a heating circuit; a thermionic detector valve also having input and output electrodes and a heating element in a heating circuit; a source of current for inclusion in circuit with each of said heating elements; a rheostat including a resistance and a switch arm connectible with different portions of the resistance to vary the amount thereof that is included in circuit, said switch arm and the portion of the resistance selected thereby being serially in the heating circuit of said radio frequency amplifying valve, the heating circuit of the detector valve being independent of the heatingcircuit of the radio frequency amplifying valve; a switch in the heating circuit of the detector valve; and means controlled by said switch arm for completing the circuit opening movement thereof and for opening the switch in the heating circuit of the detector valve and rendered operative by. said switch arm when said arm is near the free extremity of said resistance.

In witness whereof, I hereunto subscribe my name.

- CHRISTIAN W. HANSEN.

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