Coaxial cable - inductance coil
Coaxial resonators are widely used in the ranges of ultra-short waves. At LW the amount of such resonators (even relatively small - the so-called helical) not reach acceptable values.
Meanwhile, segments of coaxial cables can be successfully used in generators instead of inductors, the quality factor and temperature stability of such a "coil" will be quite high. If it is done from a modern slim cable, even in the range of short waves similar "coil" will take a little places: the cable can be twisted into a small Bay.
The figure shows the adjustable oscillator frequency synthesizer coherent LW radio stations. He assembled a field effect transistor V3 on a "capacitive treatacne". The role of the "coil" inductance L1 here performs a short-circuited segment of a coaxial cable. When specified on the circuit component values and cable length 25 cm working frequency of the generator is 50 MHz (for transfer to the operating frequency range she further shares digital circuits 10).
The oscillator frequency can be changed conventional variable capacitor or varicap, as is done in the described generator.
The generator can be performed on the transistor series KP (requires selection of the resistor R2) Type applied to varactors depends on the required range of frequencies, shutting off the generator.
Publication: N. Bolshakov, rf.atnn.ru