300 W PEP with 2 MOS transistors BLF177(1.6 ... 28 MHz)
The BLF177 is an RF Power MOS transistor
for the HF and VHF range in a 4 leads flange SOT121 encapsulation. For the
frequency range 1.6 - 28 MHz a wideband push-pull power amplifier has been
developed with 2 BLF177 having an output power of 300 W PEP at an
intermodulation distortion level below -30 dB.
The transistors operate in class-AB at
VDS = 50 V and a quiescent current of 0.5 A each.
CONSTRUCTION OF THE AMPLIFIER
r = 4.5. The position of the components
is on one side and the other side serves as a groundplane. Connections to the
groundplane have been made with rivets and with straps under the source leads
and at the edges of the PC-board on the in- and output side.eFor the printed circuit board double Cu-clad epoxy fibre glass has been
used with a thickness of 1/16” and
The printed circuit board has been
attached to a solid copper plate which functions as a heatsink.
Around the position of both transistors
a tube has been soldered in the copper plate to controle the temperature by
means of a watercooling system. For a good thermal contact between heatsink and
transistors heatsink compound has been used.
YB0BAJ ...jan13,2021
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