UHF signal generator. Encyclopedia of radio electronics and electrical engineering
Encyclopedia of radio electronics and electrical engineering / Measuring technology
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When establishing amateur radio structures operating at frequencies above 1 GHz (for example, in the 23 cm amateur band), a highly stable signal generator is required. It is not difficult to make it if a radio amateur has a quartz resonator at a frequency of 27 ... 50 MHz.
Schematic diagram of the generator is shown in fig. 1. The master oscillator is assembled on a transistor VT1, the frequency multiplier is on a diode VD1. The necessary harmonic of the original signal (for example, the 29th for the amateur band of 23 cm when using a resonator at a frequency of 45 MHz) is allocated by the L3C6 circuit. The bias voltage on the diode VD1 is created automatically. Its optimal value (according to the maximum signal of the required harmonic) is set by the trimming resistor R4. According to the same criterion, the level of high-frequency voltage supplied to the multiplier from the master oscillator is selected (with a tuning resistor R3). If necessary, the output signal of the generator can be modulated. The required modulating voltage level is set by a variable resistor R5.
Ris.1
The generator uses a conventional high-frequency diode (not designed to operate in the UHF range). If you replace it with a Schottky diode, the output signal level will increase noticeably.
The oscillatory circuit L1C2 is tuned to the frequency of the quartz resonator. The design of the coils L1 and L2 is not critical (the ratio of their number of turns is about 10). Choke 15 is a frameless coil (10 turns) with a diameter of 13 mm.
Elements VD1, C4, C5, L3-L5 are mounted on a board made of one-sided foil material, placing all the parts on the side of the foil. The L3C6 circuit is a half-wave line adjusted by a capacitor. Its dimensions for the amateur range of 23 cm are shown in fig. 2. Make a line from a copper strip, bend and solder both ends of it to the foil. The connection loop L4 is bent from a wire with a diameter of 1 mm. and located a few millimeters from the line L3.
Ris.2
By increasing the longitudinal dimensions of the line (in proportion to the decrease in the operating frequency), the described generator can be used to tune, for example, UHF television converters.
The generator is fed from a stabilized source with a voltage of 9 ... 12 V.
Transistor VT1 can be replaced with KP303E, diode VD1 - with KD522 or KD514A. Quartz resonators for a frequency of 27 ... 30 MHz are available in sets of the "Quartz" series for radio-controlled models.
Literature
- Prufostillator fur microwell. - QSP, 1988, No. 7, S. 20, 21.
Publication: N. Bolshakov, rf.atnn.ru
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