Zenith – Model ZE-18 Power Supply Schematic for Models 35PX 35APX 37A – Gernback
For a lot of earliest Zenith Radios, an AC Power Supply was optional because battery power was still the main source of power for most radios, and there were significant issues with noise from A/C power supplies
Cost was also a major concern for consumers, continual replacement of the battery could eventually become more expensive than a power supply, but it was a monthly cost, no an upgrade cost
Zenith – Model ZE-18 Power Supply Schematic for Models 35PX 35APX 37A – Gernback
