McVitie Weston valve collection, STC early tetrode valve
STC early tetrode valve, pear-shaped bulb with top pip, (RMW/Y19 - McVitie Weston number), by Standard Telephones and Cables Limited.
STC early tetrode valve, pear-shaped bulb with top pip, (RMW/Y19 - McVitie Weston number), by Standard Telephones and Cables Limited.