This 4-waveband converter circuit was found in Radio Craft September 1948. The power supply is not given, but the supply voltages are indicated.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...