New Rev B of PS-3 includes a house-ground circuit, just like the PS-1.
The PS-3's PCB is only 4" by 4" and, like all GlassWare PCBs, is extra thick (0.094 in), US-made, with heavy 2 oz-copper. The PCB holds both a simple RC pi-filtered high-voltage power supply and a low-voltage power supply and low-voltage regulator. The low-voltage regulator is meant to power the tube heaters; the high-voltage power supply, the rest of the tube circuit.
The high-voltage portion of the PS-3 power supply uses four solid-state ultra-fast-recovery rectifiers, a simple RC pi-filter to achieve a fairly quiet B+ voltage, which can span from 100V to 350V. The 5W series resistor (300, 1k, 1.5k, 10k supplied) can be replaced by an external choke. And just like the PS-4, the PS-3 can DC reference the heater regulator to ground or 1/4 of the B+ voltage or left floating, with only a shunting capacitor to ground. The PS-3 power supply PCB is equal to raw DC power supply portion of the PS-1 PCB and an H-PS-1 PCB welded together. It's B+ output voltage is not regulated, but then it is neither as expensive nor complex nor fragile nor as current-limited as the typical high-voltage regulator.
The low-voltage regulator’s power supply is flexible enough to allow either a conventional full-wave-bridge and full-wave center-tapped rectifier arrangement or a two-rectifier voltage-doubler configuration, allowing for more latitude in power transformer selection; this regulator can be set to either 6.3V or 12V or 12.6V.
Most power transformers intended for tube use hold 6.3Vac heater windings, not 12.6Vac. When applying AC to the heater elements, the lower voltage works well. But when delivering regulated DC voltage to the heaters, a 12.6Vac winding is preferred, as the regulator requires voltage headroom and the rectifiers will entail their own voltage loses. Fortunately, the PS-3 heater power supply can be configured as a voltage doubler setup, which will effectively double a 6.3Vac winding's voltage, but at the cost of half the potential current delivery (there are no free lunches).
PS-3 kit includes PCB, for standoffs with screws and O-rings, 16 capacitors, 10 rectifiers, 11 resistors (1/2W, 1W, and 5W), heatsink, and 20-page user guide.
Transformer not included.