I need a powersupply for a radio board (I will shield it), and have experienced bad interference from step-down converters. I have been told to use linear regulators (LM317 or LM350) with caps to trim the current. Am I correctly informed?
I have several boards, one to receive and one to transmit. Both take 4-6V in, and consume no more than 300mA. I've also found USB supplies (both battery, charger and laptop) to be very noisy, compared to just 3 AA batteries in series. Probably because they are backed by some sort of switching power supply hooey.