HP specifications on the power supply requirements for the Z3801A (BSC version, the one most common) are 54 Vdc nominal, and at least 46 Vdc starting, with an input power requirement of nominal 25 Watts. Many users have a 48 volt switching power supply rated at an amp or more, and this seems to work for many. Some users report that their Z3801A receivers require more than 48 volts to start properly. In particular, voltages near the nominal 54 volt area are needed. Also, some inherent problems using current limited power supplies to power the internal receiver switching supplies have been reported.

Perhaps the simplest power supply that is also the least expensive that will circumvent these problems is a simple unregulated power supply consisting of a transformer, diode bridge, and filter capacitor. It is also fairly efficient, and if built inside the receiver cabinet it won't add a lot of heat.

A power supply of this type was used to further investigate the turn-on characteristics and current requirements of a typical Z3801A receiver. Gary Thurmond, W6STR provided this graphic that shows operation of his power supply when constructed with a 37.8V secondary built with Radio Shack components:

A B&B Electronics data acquisition module, model 232SDA12 was used to collect the voltage and current information. It is a 12 bit, 11 channel A/D to RS-232 module. The resulting data file was then imported into Microsoft Excel to create the plot.