This shortwave preselector was found in the July 1994 issue of Radio Electronics magazine. The circuit is suitable for telescopic antennas, matching the impedance with the receiver used.
This circuit was found in a 1973 publication. The SCR may be the TIC106 and must use a heat sink,...
This circuit is from the time when slide projects were used. We find it in a 90's Wels’ Think...
This circuit was found in a Radio Electronics Constructor, English magazine of April 1976; The...