VINTAGE EXCELLENT KENNEDY 521 MARCONI ERA 2 STAGE OLD ANTIQUE RADIO AMPLIFIER. Please see photos to determine condition yourself. This is a genuine vintage vacuum tube amplifier produced by The Colin B. (San Francisco / Saint Louis). It was designed as a companion unit for Kennedy regenerative radio receivers to provide two stages of audio amplification. Key Features & Markings. “Type 521 Two Stage Amplifier” clearly marked on the front panel. Kennedy Equipment logo and company markings (San Francisco / Saint Louis). Original metal serial number plate: L4621W1. Bakelite knobs, filament controls, binding posts for A/B batteries, phones output, and antenna/tuner connections. Original wood base and dark finish case. Perfect for antique radio collectors, early wireless enthusiasts, or display with a Kennedy 281 or similar crystal/regenerative set. A piece of radio history from the dawn of the broadcast era! Condition: Good vintage condition for its 100+ year age. Shows honest wear, patina, and surface dust consistent with age. Untested (tubes included in photos). All original components appear present but I’m not 100% sure Great display piece as-is.