2m PA with 2x 4CX250
by
LA0BY
This
page provides information on the design and
practical implementation of an inexpensive 144
MHz high power amplifier using a pair of ceramic
tetrodes, type 4CX250B, in a push-pull
configuration. The amplifier has been built in
many variations. I have used it mainly for MS and
EME operation for many years.
View
of anode circuit
Important
design features and measured operating parameters
are displayed in the manual (WfW 2.0, 21 kB). The
schematic diagrams were originally drawn by
Designer 3.1. In order to make them come out
independently, the drawings wereexported into GIF
and JPEG format. Those may be imported into Word
documents and printed with reasonable, but not
perfect quality.
Schematic diagrams
Switching and metering circuits: GIF 13 kB, JPEG
57 kB
Mains power wiring and connectors: GIF 15 kB,
JPEG 68 kB
Power supply circuits: GIF 14 kB, JPEG 69 kB
RF circuit: GIF 11 kB, JPEG 44 kB
Equipment configuration for EME, including
sequencing: GIF 14 kB, JPEG 71 kB
Whole set of drawings as ZIP-file: Compressed GIF
64 kB, Compressed JPEG 205 kB
Pictures of power supply unit
Front, 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
Please
see web pages LA0BY
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