Here's the short version: Something was broken at VPR's transmitter site on Mount Ascutney. The station was off air or at low power for a long period. It was a complex problem that took a while to diagnose and fix. VPR listeners were patient and understanding while VPR engineers worked long days and weekends. Now the problem is fixed!
If you would like to know more, read on.
We thank our listeners for their patience while we worked to get 89.5 WVPR back to full power. The problem was related to a faulty combiner element (see photo below). WVPR shares a common antenna on the tower atop Mt. Ascutney with another broadcaster, and the combiner is a key piece of equipment that keeps both stations on the air.
Normally this combiner system works quite well, but recently, a series of events led to some major damage to one of the components, so huge amounts of output power from the transmitter were being reflected back into the output. Fortunately, there is a device that protects the transmitter from severe damage by automatically reducing this reflected power. That’s what made 89.5 go to low power, making it difficult for most of you to hear. We knew what was happening, but we didn’t know why.
Thus began a long period of investigation of the many complex elements which form a modern transmission system - a search that would even have made Sherlock Holmes scratch his head.
What we eventually learned was that the filter was damaged inside - and that was what created the problems.
Once it was determined for certain what the problem appeared to be, we called the factory in Maine. The factory engineer came to Vermont and brought the new parts with him. He was able to work with VPR's engineers to get the part replaced, reassemble the combiner, and retune it properly; so the WVPR transmitter could go back on the air again at full power.
With these extremely complex, and high powered systems, it takes a lot of careful diagnosis to really know what is going on, and that involves taking things apart, turning them on and off, and otherwise disrupting operations. Add to that the fact that it is still 'mostly winter' on top of the mountain, so travel on snowmobile or tracked vehicle can be slow and difficult.
We fully appreciate how disruptive this was for our listeners, and we worked extremely hard to resolve the problem as quickly as possible. Thanks again for your patience during this time. We also appreciate the kind words sent via email and posted on Facebook.
-Rich Parker, GSEC
VPR's Director of Engineering