Simple sweep frequency generator
Abstract
A sweep frequency generator is described whose center frequency can be varied from 10 kHz to 50 MHz, with seven 1 to 3 and 3 to 10 scales covering the 10 kHz to 30 MHz range and one 3 to 5 scale for the 30 to 50 MHz range. It consists of a tunable pulse generator with output voltage attenuator, a diode mixer for calibration, and a sawtooth voltage generator as a source of frequency deviation. The pulse generator is a multivibrator with two emitter coupled transistors and two diodes in the collector circuit of one. The first diode extends the tuning range and increases the frequency deviation, the second diode provides the necessary base bias to the other transistor. The pulse repetition rate is modulated either directly by the sweep voltage of the calibrating oscilloscope, this voltage being applied to the base of the transistor with the two diodes in its collector circuit through an additional attenuator or a special emitter follower, or by the separate sawtooth voltage generator. The latter is a conventional two transistor multivibrator and produces signals at any constant frequency within the 40 to 60 Hz range. The mixer receives unmodulated signals from a reference frequency source and produces different frequency signals which are sent through an RCR-filter to a calibrating oscilloscope.
- Publication:
-
USSR Rept Electron Elec Eng JPRS UEE
- Pub Date:
- January 1985
- Bibcode:
- 1985RpEEE.......50Y
- Keywords:
-
- Frequency Synthesizers;
- Sweep Frequency;
- Calibrating;
- Diodes;
- Mixing Circuits;
- Multivibrators;
- Pulse Repetition Rate;
- Radio Frequencies;
- Transistors;
- Voltage Generators;
- Electronics and Electrical Engineering