This QST circuit generates 4 frequency signals according to the crystals used. Transistors admit equivalents although the indicated types can still be found with some ease.
This circuit was obtained from an Electronics World magazine from 1992. The circuit provides an...
This other high stability thermocouple amplifier uses an 80's operating. The circuit can be used...
We found this circuit in a 1975 radio amateur documentation. The circuit uses TTL technology and...