DE1591097C - Method for pre-adjusting the oscillator circuit in diode-matched heterodyne receivers - Google Patents

Description

3 4

will see that this tap is attenuated in terms of high frequency or the oscillator voltage with a half

is connected to ground potential and that the intermediate diode are limited, for example by

see the junction diode-capacitor that part of the oscillator coil L is the adjustable

and ground potential alternating voltage through damping resistor or the semiconductor diode par-

Adjustment of the capacitance of the capacitor and / or 5 alleles can be switched.

by adjusting the tuning voltage of the diode, the display of the minimum of the AC voltage u

is set to the minimum. is conveniently done with an HF voltmeter or with

With simple means, the oscillator becomes an oscilloscope, which is particularly advantageous

circuit is expanded to a measuring circuit in a bridge circuit, the harmonics of the oscillator voltage

tert to suppress its diagonal voltage in the form of the alternating io that the display device has an upper

voltage u serves as a measure for the pre-adjustment. Has cutoff frequency that is at least lower

In order to avoid an undesired detuning of the bridge as the frequency of the most strongly occurring upper

due to undefined scattering of the oscillator coil L with wave; mostly this will be the first harmonic, so

To avoid safety, it is expedient and that the upper limit frequency is lower than the first

Particularly advantageous, 15 harmonics can be present for the duration of the pre-adjustment,

remove the alignment core of the oscillator coil. The mentioned adjustment of the tuning voltage,

It is also tapped for both the pre-adjustment and that on the potentiometer P and the diode C _{0 is} also supplied for the normal operation of the oscillator is not controlled too much. For this purpose, the circuit can be switched with an adjustable resistor in series with 20 licher and adjustable resistance R _s.

1 sheet of drawings

Claims (6)

adjusted, or, more precisely, to a frequency Claims: / 0 + / z> which is higher by the intermediate frequency / 2. To be able to control the adjustment, modulated 1. Procedure for the 'pre-adjustment of the oscillator - one the input voltage in the amplitude and circled in diode-matched superimposition 5 comes as KTiteriüm fürdetr ^ Äbjgleich a low receiver, in which the tuning diode of the frequency voltage ^ m ismpia ^ ger output. Then a capacitor is connected to the oscillator circuit in series, and a voltage is switched on at the lowest level, the capacitance of which also determines the synchronism of the frequency, which is the input of the receiving input and oscillator circuit, and balances the oscillator circuit with the help of a characterized in that the oscil- io variation of its resonance circuit inductance L decreases.
lator coil (L) with the desired ratio of the maximum diode capacitance (C _{0 max} ), possibly several times, in order to ensure the mutual influence on the capacitor capacitance (C ₅ ) when balancing at the upper and lower end of the band Tap (A) is provided to compensate for this tap. When the oscillator circuit is adjusted to the Fung terms of high frequencies to ground potential (O) 15 to be received frequency range, and in that between the is the input circuit at two frequencies, .the connection point (B), diode-capacitor and previously calculated can, for Achievement of DC ground potential AC voltage (u) is balanced in three points to maximum receive power by adjusting the capacitance of the capacitor. These two frequencies are slightly (C _s ) and / or by adjusting the tuning ao higher or slightly lower than the frequency / voltage (U ₁₁ ) of the diode (C ₀ ) to the minimum and / or the band ends. With this adjustment is made. a synchronization of the receiver in three points ( 1 2. The method according to claim 1, characterized in that in the two adjustment points and in indicates that for the duration of the pre-adjustment a point between these points approximately in the alignment core of the oscillator coil is remote 25 from the center of the tape. will. With the diode-matched receiver, this is sufficient 3. The method according to claim 1 or 2, thereby not ser adjustment. Since the oscillator is always on a characterized in that the voltage minimum fluctuates with a frequency which is higher by the intermediate frequency RF voltmeter or an oscilloscope, d. that is, because the frequency spacing between the is shown. 3 ° resonance frequency of the oscillator circuit and the re- 4. The method according to claim 3, characterized in that a display device with a der- receiving range must be used constant equal to the intermediate frequency low upper limit frequency is used in the oscillator circuit that the harmonics of the oscillator frequency tuning element a capacitor C _x , the so-called largely suppressed. 35 padding capacitor, connected in series, its 5. The method according to any one of claims 1 capacity entbis the frequency range of the oscillator 4, characterized in that constricts at least speaking. part of the oscillator coil (L) an adjustable The required size of the padding capacitor Is connected in parallel, depends directly on the maximum capacity of the tuning with which the amplitude of the oscillator voltage 4 ° capacitor in the oscillator circuit. With rotary condenser can be adjusted. . capacitors, the maximum capacity of the rotary condenser 6. The method according to any one of claims 1 sators C, guaranteed within tight tolerances. The litter up to 5, characterized in that at least ungen in varactor diodes are larger, so , a part of the oscillator coil (L) has a semi- that a tight tolerance at high cost and at ν terdiode is connected in parallel, which the oscillator 45 of a large number of capacitance diode groups door tension limited. leads. One must therefore for the large-scale production of receivers with larger tolerances of the maximum capacity Calculate the efficiency C _{Dmax of} the capacitance diodes C _n and 5 ° either the padding capacitor located in the oscillator circuit according to the maximum capacity of the The invention relates to a method for making pre-tuning diode C ₀ (FIG. 2) adjustable or setting its tuning voltage U _a equal to the oscillator circuit in diode-tuned ones so that im superimposition receivers where the tuner has a certain maximum diode capacitance of the oscillator circuit there is a capacitor in series 55, the value of which is connected to the value of the circuit, whose capacitance co-determines the synchronization between the permanently installed padding capacitor assigned to the input and oscillator circuit; is arranged. This is a pre-adjustment of the oscillator Necessary to explain the underlying circuit of the invention. The object of the invention is to provide these variable capacitors matched superimposition 60 pre-adjustment with the least possible additional expense receiver, z. B. for the medium wave range, both with regard to the cost of measuring devices as written, which is tuned over a wide frequency range also with regard to the additional switching to be provided and to make its intermediate frequency feasible in the elements.
The order of magnitude of the receiving frequency is. The method of the type mentioned above is a voltage with the highest 65 digits these requirements according to the invention by feeding the frequency f _o to be received and that the oscillator coil is connected to the desired oscillator circuit with the aid of the ratio of maximum diode capacitance connected in parallel to it to Kon-Trimmerkondensators C ₁ (F i g. 1) on this frequency capacitor capacitance corresponding tapping