This circuit was found in an ancient American documentation. With it is possible to double the frequency of a transmitter For the range of 6 meters obtaining 8 W. The circuit makes use of varicap.
This UAA170 application circuit was taken from Siemens' own integrated circuits manual from 1976....
The astable multivibrator shown by the figure can produce signals in the 10 to 10 000 Hz band...
Found in an American publication from the 1980s, this circuit can be found in commercial sound...