As many of you know, RIPR owns and maintains the 1290AM site on the Providence/North Providence town line. Our NPR satellite downlink is there, and we lease the frequency to our friends at Latino Public Radio.
In the past, the site was largely a pond (Whipple Pond) with Douglas Ave forming part of a dam in the eastern corner. After the torrential rains of 2010, the dam broke and the pond drained. Now the West River flows freely through the site.
We have put a temporary setup in place with a donated 30 watt transmitter on loan (with the antenna array's gain factor of 2.1, it's really more like 63 watts of Effective Radiated Power), and a special radio that's tuned to 102.7FM (there's a high-gain FM antenna on the rooftop tower) and puts out the composite signal directly into the new transmitter. This effectively makes 91.5 into a "repeater" of 102.7FM.
BOO! This time on the Engineer’s Corner, we’ll talk about PHANTOM POWER. Usually not as ghoulish as one might expect, phantom power has to do with microphones. Specifically, some microphones have active circuitry inside them. That means they need power to operate, but it’s unwieldy to run a separate power cord and audio microphone cable. So a phantom circuit is used to provide DC power on the same three wires (positive/hot, negative/cold, and ground) out to the microphone that the audio from the mic also uses.
A phantom circuit is one of those nifty things in electronics that looks, to the layman, like it can’t possibly work...but it does anyway.