US1976001A - Wireless receiver - Google Patents

Description

Get. 9, 1934. c K s 1,976,001

WIRELESS RECEIVER Filed Sept. 25, 1930 0 O 0 0 0 O Q 0 O 0 0 [m/en for Hub erZCym'Z Atkins,

Patented Oct. 9, 1934 UNITED STATES PATENT OFFICE WIRELESS RECEIVER Hubert Cyril Atkins, Hayes, England, assignor to Victor Talking Machine Company, a corporation of New Jersey 2 Claims.

The present invention relates to wireless receivers employing a volume control in which the volume control takes the form of a potential divider shunted across the aerial circuit.

In such a receiving system the tuning of the input circuit of the receiver depends to some extent at least upon the capacity to earth of the aerial, this capacity to earth being, in effect, a condenser connected across the input circuit. As the tapping point on the potential divider is varied, however, the amount of this capacity across the input circuit varies and consequently this circuit tends to become detuned.

it is an object of the present invention to prevent or reduce the detuning effect produced in the input circuit of a wireless receiver by the variation in the capacity to earth of the aerial.

According to the present invention this object is attained by providing in a wireless receiving system having a volume control in the form of a potential divider connected across the aerial circuit means for preventing or reducing the detuning effect caused by the alteration in the efiective capacity across the input circuit comprising a small condenser connected effectively in series between the input circuit of the receiver and the capacity to earth of the aerial.

The invention will be described by way of example with reference to the accompanying drawing in which Fig. 1 shows the invention as applied to a wireless receiver employing transformer coupling between the aerial and input circuits, whilst Fig. 2 shows the invention as applied to a receiver employing a single tapped coupling coil, or auto transformer.

Referring to Figs. 1 and 2a high resistance 1 constituting a potential divider is connected between the aerial and earth and the received oscillations are transferred from the aerial to the grid circuit of the first valve of the receiver through a high frequency transformer 2, 3. A small condenser 4 is connected between the variable contact of the potential divider and one end of the primary winding 2 of the transformer, the other end of the primary winding being connected to earth. The ends of the secondary Winding 3 of the transformer are connected to the grid and filament respectively of the first valve 5 of the receiver. This valve may be a detector valve or a high frequency amplifier. The filament of the valve is connected to earth and a variable condenser 6 is connected across the secondary winding of the transformer. The resultant of the capacity of the small condenser 4 and Winding of the transformer therefore remains substantially constant notwithstanding the variations in the effective aerial capacity due to movement of the tapping point on the potential divider.

Although the invention has been described with particular reference to a receiving system employing transformer coupling between the aerial and input terminals, it can also be applied to systems using other forms of coupling. For example, in Fig. 2, the invention is shown as applied to a receiving system employing a single tapped coupling coil or autotransformer 2 in place of the usual high frequency transformer, the terminals of the coil being connected to the grid and filament respectively of the first valve 5 of the receiver. The condenser 4 is connected between the variable contact of the potential divider and the tapping on the coil 2.

I claim:

1. In a radio receiving system, a resistor having terminals adapted, respectively, to be con- 30 nected to an antenna and to ground, a high frequency transformer having input and output terminals, a connection between one of the input terminals and the ground terminal of the resistor and a connection serially including a capacitor 8 connected in shunt relation to the secondary of the high frequency transformer.

HUBERT CYRIL ATKINS.

Images