DE1081512B - Overlay receiver - Google Patents

Description

The invention relates to a heterodyne receiver in which always all of the tuning range appropriate vibrations are allowed to the mixer tube, as z. B. in the so-called single-range receivers the case is. With these receivers you can use a single voting group get by that the intermediate frequency is chosen higher than the highest receiving frequency, so that the Mirror frequencies fall outside the tuning range and therefore only the oscillator is tuned needs to be.

According to the invention, a two-pole rectifier is used as a mixer tube in a receiver of the type described above is used, the circuit of which is a parallel oscillation circuit tuned to the intermediate frequency and a resistor bridged by a capacitor. It becomes the The advantage achieved is that the selectivity of the receiver is considerably increased because of a retroactive effect of the intermediate frequency circuit an automatic preselection on the received vibrations is brought about.

The use of a diode as a mixer tube is known per se. It is also known the local To feed vibrations through one of the circuits of a tunable input band filter to the mixer diode «

It is also known to use a grid-current-carrying rectifier in a single-range receiver Use triode. This rectifier circuit is in some respects the diode rectifier equivalent, but the effect according to the invention can do not occur because of the intermediate frequency circuit lies in the anode circuit and therefore cannot affect the received oscillations.

The invention is explained in more detail with reference to the drawing.

Fig. 1 shows a known mixer circuit in which a diode D serves as a mixer tube. This forms a closed circuit with a resistor R bridged by a capacitor C , a source of local oscillations, an intermediate frequency circuit and a source of incoming oscillations. Is cü; the frequency of the currently desired station and ca _m the frequency to which the intermediate frequency circuit is tuned, the frequency ω _{ρ of} the oscillator must therefore be chosen such that cop = ω, · + <a _m and for single-range receivers co _p = ωι + <a _m .

The impedance of such a circuit for frequencies in the vicinity of ω / is that of the parallel connection of a resistor R and one to ω; matched circuit, the impedance and absolute width of which are the same as those of the intermediate frequency circuit. The resistor R from Fig. 1 becomes a heterodyne receiver

Applicant:

Philips Patentverwaltung G.m.b.H., Hamburg 1, Mönckebergstr. 7th

Claimed priority: The Netherlands, September 8, 1939

Claimed priority:

Applications according to Act No. 8 AHK are made and before the

Arbitration Commission for Goods, Rights and Interests

pending in Germany

Johan Haantjes and Bemardus Dominicus Hubertus Tellegen,

Eindhoven (Netherlands) have been named as inventors

only partially bridged by capacitor C , this equivalent circuit changes somewhat, but the tuned circuit remains.

If, therefore, when the oscillator is tuned to ω _ρ, a broad frequency band lying on both sides of ω, Pre-selection takes place. The latter is of particular importance with the single-range receiver.

In Fig. 2 is a frequency scale of such an Infradyn device shown.

The frequency range / extending from ω ₀ to ω _ε is the range of the incoming vibrations.

(o _m is the intermediate frequency.

The Bh O d Bih d Oill extending from ω _Μ + ω ₀ to ω _Μ + ω _ε

_{0 ε}

Area O is the area of the oscillator.

The area 5 ¹ of 2co

co

up to 2

_{m 0 8th}

the range of the image frequencies to be suppressed. This suppression takes place with the single-range receiver usually by means of a low-pass filter.

Fig. 3 shows an embodiment of a single-range receiver according to the invention.

The vibrations picked up by an antenna ^ are transmitted to the input side of a low-pass

009 509/255

filters F supplied. The primary winding of an intermediate frequency transformer M, a diode O, a resistor Α bridged by a flat capacitor C and an oscillator O are connected in series between the output terminals of this filter. The filter F suppresses the image frequencies, and the automatic-preselective character of the rest of the circuit ensures that cross-modulation and whistling tones from the stations that are not currently desired are not disruptive.

The latter effect can be further improved by choosing a high oscillator voltage will.

Claims (1)

PATENT CLAIM: Superimposition receiver, in which all vibrations belonging to the tuning range are always for Mixing tube are permitted, characterized in that a two-pole rectifier is used as the mixing tube whose circuit is a parallel oscillation circuit tuned to the intermediate frequency and a resistor bridged by a capacitor. Considered publications:
Philips Trensmitting News., September
Vol. V, H. 3, pp. 76 and 77. 1938, 1 sheet of drawings