power

Engineer's Corner
10:41 am
Mon March 31, 2014

TheEC: West River Runs High Through 1290

The West River runs high through the 1290AM tower site. Water levels are a good two feet above normal.
Credit Aaron Read

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.

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Engineer's Corner
1:43 pm
Tue November 12, 2013

TheEC: 91.5 is Back On the Air

From top to bottom, Bext LEX30 transmitter, Dayton 210 FM receiver tuned to 102.7 to get programming to feed the transmitter, and Inovonics 631 FM receiver to monitor 91.5 on the speakers above.
Credit Aaron Read

As of Tuesday November 12th, WCVY is back on the air in limited fashion.   As you know, WCVY suffered catastrophic damage to its equipment and facility from a roof leak during a thunderstorm in August.   The entire space had to be gutted to the concrete walls, and new electrical wiring and drywall installed.  Much of the transmitter gear either took direct water damage (e.g. electricity shorting out) or took indirect water damage (e.g. rust and other corrosion), and eventually a lot of it failed completely.

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.

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Engineer's Corner
1:26 pm
Fri July 12, 2013

TheEC: Phantom Power

A typical phantom power circuit.

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.  

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