The PS-22 is a regulated bipolar low-voltage power supply that puts out between +/-5Vdc to +/-24Vdc. It uses two low-dropout adjustable 1.5A voltage regulators, an LD10866 for the positive output and an LT337AT for the negative output. The PS-22 PCB is only 3.7" by 3.2" and, like all GlassWare PCBs, is extra thick (0.094 in), with heavy 2-ounce copper traces. The rectifiers used are ultra-fast MUR410G types, each of which are shunted by a 0.01uF ceramic capacitor to reduce RFI creation. The power supply requires a center-tapped power transformer, which is not included.
Either a 1.5 inch or 2.5 inch tall heatsinks are the options. The 1.5 inch tall heatsink presents a thermal resistance of 3.7C/W, while its 2.5 inch brother offers a low 2.6C/W resistance. How do these two thermal resistances translate into actual performance? If the 3.7C/W heatsink were attached to a TO-220-encased resistor that dissipated 10W of heat, the heatsink would increase in temperature by 37C, as in 37 degrees celsius (centigrade). Now 37C is not that hot, as it is your core body temperature. But the 37C must be added to what ever temperature the heatsink was at prior to the resistor's heat generation. Usually, we assume 25C, 77 degrees in Fahrenheit, as the average room temperature. Inside a tube-filled chassis, this assumption might fall short of reality by 15C or more. On a hot summer's day, inside your tube power amplifier chassis, the ambient temperature might be closer to 50C (122 degrees in Fahrenheit). Ouch! As 50C added to 37C yields 87C, which produces a burning hot heatsink and, most probably, a toasted voltage regulator.
My own self-imposed limit to heatsink temperature is 60C, as that is about as hot as I can bear to touch without gloves. So, if we work backwards, and if we assume 35C to be the internal enclosure temperature, and if we want to limit the 3.7C/W heatsink to no more than 60C, then the heat generating device, be it a voltage regulator or transistor or MOSFET or power resistor, cannot produce more than (60C - 35C) / 3.7C/W or 6.75W. If we use the taller heatsink, however, with is lower 2.6C/W thermal resistance, we can allow dissipation up to 9.6W. Of course, if the tall heatsink does not fit in the enclosure, its lower thermal resistance will not do us any good.
Most OpAmp-based circuits draw relatively little current, say a total of 50mA, which against a voltage regulator's voltage drop of 4Vdc equals only 0.2W of heat. But if the OpAmp circuit is a headphone amplifier or a complex OpAmp-based circuit, then the larger heatsinks become a much bigger asset.
The kit includes all the parts, capacitors, resistors, rectifiers, regulators, including the user guide, heatsink mounting part kits, and four sets of standoffs and screws and O-rings. It offers the option of a 1.5in or 2.5in tall heatsinks.