GB719904A - Improvements in or relating to high frequency oscillation generating circuits - Google Patents
Improvements in or relating to high frequency oscillation generating circuitsInfo
- Publication number
- GB719904A GB719904A GB25759/52A GB2575952A GB719904A GB 719904 A GB719904 A GB 719904A GB 25759/52 A GB25759/52 A GB 25759/52A GB 2575952 A GB2575952 A GB 2575952A GB 719904 A GB719904 A GB 719904A
- Authority
- GB
- United Kingdom
- Prior art keywords
- frequency
- valve
- amplifier
- phase shift
- feedback
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03C—MODULATION
- H03C3/00—Angle modulation
- H03C3/02—Details
- H03C3/09—Modifications of modulator for regulating the mean frequency
Landscapes
- Oscillators With Electromechanical Resonators (AREA)
Abstract
719,904. Frequency modulation ; valve generating circuits. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE. Oct. 14, 1952 [Oct. 25, 1951], No. 25759/52. Classes 40 (5) and 40 (6) In an arrangement for producing frequency modulated high frequency oscillations wherein an oscillator determines the mean frequency and is provided with an amplifier in the feedback circuit for maintaining oscillations, at least one of the stages of the feedback amplifier has an output impedance which is substantially capacitive in order to provide a 90 degrees phase shift. By this means the effect of small capacitance variations due to exchanging valves &c. on the phase shift in the feedback amplifier is minimized. As shown in Fig. 1 a valve 1 is loosely coupled to a frequency determining circuit 2, which may be crystal controlled and feedback is provided by an amplifier 3 whose output is fed back to the grid of valve 1. The feedback voltage is also applied through a circuit 5, producing a phase shift of 90 degrees to a valve 4 which is modulated by a signal Um, the resultant oscillations supplied to circuit 2 varying in phase in accordance with Um and thus producing a variation of frequency in accordance with the signal Um. In the feedback amplifier, Fig. 2, Ca represents the effective self-capacitance of the anodes of valves 8 and 9 to earth, and since the anode resistance 11 is large compared with the reactance of Ca the effective output impedance of the valve 8 is substantially the capacitive reactance of Ca. Adjustable resistors 10 and 12 enable the phase shift to be set to the required value for each stage. In valve 9 amplitude limitation is effected by grid rectification, the meter 13 providing an indication. The resonant frequency of the circuit 14, 15, which incorporates the capacitance Ca, is arranged to be below the operating frequency so that it operates near quadrature. The method of adjusting the amplifier consists in adjusting the phase shift until a minimum of amplitude modulation is present, which may be detected by means of telephones inserted at 16.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE719904X | 1951-10-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB719904A true GB719904A (en) | 1954-12-08 |
Family
ID=6627312
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB25759/52A Expired GB719904A (en) | 1951-10-25 | 1952-10-14 | Improvements in or relating to high frequency oscillation generating circuits |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB719904A (en) |
-
1952
- 1952-10-14 GB GB25759/52A patent/GB719904A/en not_active Expired
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