This circuit was found in documentation from the 1970s. However, it can be implemented with modern transistors such as 2N2222 for Q1 and BF494 for Q2. The crystal depends on the desired frequency.
With the name of transitube we find this MW receiver in documentation from the 50's. It uses a...
This common operational configuration can be implemented with modern equivalent. Next to the...
This circuit was obtained from an English magazine from 1977. The magazine no longer exists, but...