WD8DAS SB-230 Amplifier Tube Retrofit Project


Air-cooled Russian GI-7B triode replaces the conduction-cooled 8873.
Heatsink removed, plenty of vent holes all around. and a small muffin fan running at reduced voltage.

Top view.

Under the RF chassis.

High voltage section.

Filament and 12vdc power supplies.

Rear view.
GI7B tube datasheet
Converted amp schematic diagram
W4ZT bias board documentation