Power Amplifier Dressler D200 (144MHz)
Mechanical modifications
I have added a robust metallic handle on the right side and tiny rubber feet on the opposite one. The handle is mounted on the bottom part of the box, close to the heaviest parts of the amplifier - both transfomers:
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Tuning was
sometimes very tough due to slight misaligment of the shafts.
I removed the rigid joint between the tuning knob and the shaft
with the tuning plate and replaced it with home-made rag joint.
Now the knob rotates very smoothly:
Electrical modifications
The DIL integrated
circuit (stabilizer) for the antenna pre-amplifier seemed never
been installed on the PCB. Instead, there was 7812 stabilizer
soldered on the top of the PCB.
To make it more robust I replaced it with 78S12 (up to 2A) and
mounted it directly on chassis for an ideal cooling:
I made a map of
some parts on the PCB (relating to the schematics in the original
documentation):
And this is the
detail how the tube (4CX250R) is mounted in the PA (no mods):
