Description of a 144 MHz high power amplifier for 2 x 4CX250B
LA0BY, last updated 18.12.2002
View of anode circuit
This page provides information on the design and practical implementation of a rather inexpensive 144 MHz high power amplifier using a pair of ceramic tetrodes, type 4CX250B, in a push-pull configuration. I have used it mainly for MS and EME operation for many years.
Important design features and measured operating parameters are displayed in theamplifier manual (26 kB PDF). The schematic diagrams (PDF 60 kB) and the following pictures reveal further details.
Pictures of power supply unitFront, rear and top (open chassis) view Close up of HV circuit Close up of grid/screen supply Pictures of RF unit Front and rear view Anode compartment Close up of output circuit Grid/cathode compartment Close up of valve sockets and neutralising capacitors Close up of grid circuit
There is also a set ofconstruction drawings (PDF 91 kB) made by OM1CW. This amplifier has been rebuilt by many amateurs, among them also DL5DBM, DL6YEH, VK3OF. You may contact them for further details.