Specific chassis numbers listed include S-61163, S-65903, S-60803, S-60804, S-63874, and S-63954. The manual provides a detailed theory of operation for the ultrasonic remote system. The cover and interior pages exhibit uniform light yellowing and toning, with minor foxing and occasional light stains.
Zenith Space-Command Service Manual 200 & 400 Series Ultrasonic 1960s Remote
The ultrasonic frequencies employed for remote commands are specified as 37.75 kC, 38.75 kC, 40.25 kC, and 41.25 kC. The paper exhibits toning consistent with age and minor spotting, primarily along the edges.