501-D Master Remote Control

This device, made in the late 40s or early 50s, is a wired remote control. It has 3 tubes - a 6AK5 RF amplifier, tuned with the "Picture" control and the Channel knob; a 6AB4 local oscillator, tuned with the Channel knob and the Sound control, and a 6BC5 mixer. On the back is a sticker, indicating it was approved by the City of Los Angeles Building and Safety department.. It was made by Coastwise Electronics Company in Los Angeles.

The output is on channel 6. However, the output channel would be inverted, with the sound carrier below the visual carrier.

The Picture knob peaks the RF amplifier to the desired channel. The Sound knob adjusts the local oscillator frequency over about a 10 mHz range.