For my Kiwi, I built my own linear power supply using an old Triad F-36A filament transformer, full wave bridge rectifier, and a 5 volt 3 amp LM1085 low dropout linear regulator. Along with the necessary filtering and decoupling caps. The power supply is plugged into a differential/common mode line filter.
A set of windings on the filament transformer are also used with a 12 volt linear regulator to supply power to my amplified loop.
The Kiwi is installed in a shed/shack in my backyard which I have the entire shack on a PowerVAR 3 stage toroidal power conditioner with a common mode pi-filter. The power conditioner is located back at my house, so it filters noise off the line before it has a chance to radiate from the feeder running to the shack and from the wiring within the shack.
The Beagle will shut down if the voltage dips below about 4.75 volts for even a fraction of a second, so you want your power supply to be able to provide a stable voltage output during moments of peak current draw (especially during start up). The cable you use to connect your Kiwi to your power supply should be of sufficient gauge as to reduce voltage drop. Depending on length, 22 to 18 AWG is typical.
