rtetro said:
Sam can probably speak to this better than I, but in so far as I have been able to determine by looking at the FCC databases, there has not been a major upgrade to the WDAS-AM signal for many, many years. The antenna was most likely designed long before the advent of contemporary directional designs.
I was doing a co-op assignment at the old General Electric switchgear plant in southwest Philly (6901 Elmwood Ave) during the summer of 1955 when WDAS left 1400 and signed on on 1480. I lived in a furnished room around the corner from the plant (7022 Paschal Ave). Back in that day, there were no such things as NIF (nighttime interference-free) contours for what were then Class IV AMs, which is what WDAS was when it was on 1400. I don't know where WDAS's transmitter was when the station was on 1400, but the night signal was unlistenable and barely audible. (Remember, Class IVs were limited to 250W-U in those days.) When WDAS signed on on 1480 as a Class IIIB, its 5 kW daytime signal, which is directional to the south, was a noticeable improvement over the previous 250W ND signal on 1400, but at night, the signal was totally nonexistent. If you look at the night pattern, you can see why; it's a four-in-line teardrop aimed southeast. 7022 Paschal Ave sits in a null to the southwest that was designed, I assume, to protect the (then) co-channel station in Richmond VA. It had the WLEE calls and shared time on 1480 with WBBL Richmond, which I believe operated only on Sundays. I suspect that, to move to 1480 from the site in Fairmount Park, WDAS had to get a waiver of the FCC rule that required (and still requires) full-time AMs' NIF contours to enclose an area in which resides at least 80% of CoL's the population. WDAS's operation on 1480 was really shoehorned in. IIRC, back in the '50s, there was a now-dark station on 1480 in Hazelton PA. To the north during the daytime, WDAS had to protect not only the 1480 station in New York City but also the Hazelton station. And I believe that there was (and probably still is) a 5-kW-U first-adjacent in Allentown.