Gil Stacy wrote: > If WOR is only concerned with the "local" and not dx market, then why does > it persist in using 50kW at night? Wouldn't 5-10kW at night serve its local > market?
I keep seeing this idea come up, and it's worth a response: no, 5 or 10 kW is no longer enough for a viable full-market AM signal in *any* large city these days. If you've never driven around midtown Manhattan or Chicago's Loop while trying to listen to AM radio, this may not seem like an obvious concept. If you have - and if you're seeing things from the station's perspective, not a DX perspective - you'll start wondering why the FCC doesn't authorize 100 or 250 kW on AM. Particularly in New York, where ground conductivity is abysmally bad (Manhattan is one big lump of solid rock, after all), 50 kW is barely enough to overcome the combination of massive electrical noise and steel-framed buildings that wreaks havoc with AM reception. Even so, reception is highly variable. WCBS and WFAN, with their transmitter site in Long Island Sound off the Bronx/Westchester line, are often completely inaudible in a car driving around Manhattan's Upper West Side, thanks to the almost nonexistent ground conductivity of northern Manhattan. WQEW, with its Queens transmitter site, is even worse. The same is true, on the opposite side, for most of the New Jersey-based AMs (WOR, WABC, WINS, WEPN, WBBR) on the East Side of Manhattan. And none of those stations does well at all in penetrating the skyscrapers of Midtown or the Financial District. WOR probably does the best at penetrating Lower Manhattan, thanks to a transmitter site directly across the Hudson and the massive amount of RF it pumps out of its directional array aimed east. Dial the power back to 5 kW on any of those stations and they'd simply disappear from the dial in large parts of the city, just as lower-powered Jersey-sited stations like WNYC 820, WWRV 1330 and WZRC 1480 already do. Want to see the remaining successful AM stations go out of business in a hurry? That would be a good place to start. Even in smaller markets, it takes a lot of RF to give an AM station a viable signal as communities keep sprawling and as the spectrum keeps getting noisier. It's no coincidence that the markets where AM is now least successful - think Atlanta or Washington, for instance, but also places like Winston-Salem/Greensboro - are the same markets where there are few (or even no) AM signals that are powerful enough to cover the whole market. Conversely, markets such as San Francisco or Chicago, with many high-power, well-sited AMs, still routinely have numerous AM signals at or near the top of the ratings. The fact that all that RF generates lots of skywave, in addition to the desired powerful groundwave, is considered an unfortunate side effect by many of today's engineers and the management above them. Too few of them understand - as we DXers do - that long-range propagation is simply what mediumwave RF does, by its nature, and that it can't be eliminated by fiat...which is kind of how we ended up in this pickle now. s _______________________________________________ IRCA mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected]
