Philip_Airtime said:
Perhaps some broadcasters with more knowledge than me can clarify this. Why were some stations that were once day-timers allowed to broadcast into the evening, while others retained their daytime status? For instance, the station I once worked for, WMNS in Olean, now broadcasts at lower power into the evening hours. And obviously, WHLD and WXRL, once daytimers, are now 24-hours. Yet, the Seneca Falls station -- or AM 1120 in Buffalo for that matter -- retain their daytime status. Was it a matter that their owners -- either current or past -- did not apply for evening broadcasts? Or are their particular frequencies protected by some clear channel station somewhere in the nation? Can anyone enlighten me here?
It helps to understand how the FCC assigned frequencies when AM was regarded as the "Standard Broadcast" band. There were/are designated power levels and station classes. Many of us continue to refer to the former terminology of Classes 1, 1A, 2, 2B, 3 and 4 (the local graveyard stations) rather than using the new Class A, B, C, D.
Stations like WBBF and WSFW operate on what the FCC designated as Clear Channel (not the corporation) frequencies. Anybody who ever held a valid Third Ticket with Broadcast Endorsement is likely capable of rattling off all the Clear Channel, Regional and Local frequencies without missing a beat.
The FCC Rules require mileage/distance separation requirements for operating on Clears Channel frequencies with a maximum power of 50 kw. Take WKBW (WWKB) on 1520. It was designated as a Class 2-B, operating with a directional antenna fulltime (DA-1) to protect KOMA on 1520 in Oklahoma City. KOMA operates DA-N to protect KB. (A friend theorizes that KB could have been DA-N when it first signed on, but that point is moot.) KMOX on 1120, like WHAM on 1180, was designated as Class 1A, operating 50 kw non-directional day and night. Other stations on these Clear Channel frequencies were required by FCC Rules to sign off at night.
Stations operating on 1300, 1270 and 1440 (among many others such as 550, 930, 950, 970, 1280, 1460) operate on designated Regional Channels, which were originally limited to a power of 5kw day and night, and also were required to protect other stations operating on the same frequency (or adjacent frequencies) by using directional antennas or reducing power at night, and in same cases day and night (DA-1.) WGR, for example, was first licensed with 5 kw non-directional during the day and 1 kw at night (1 kw DA-N) to protect WKRC on 550 in Cincinnati, which also operates with a directional antenna at night (DA-N). WBEN on 930, using a directional antenna only at night, protects WPAT on 930, in Patterson NJ.
Stations like WMNS 1360, Olean and WHHO 1320, Hornell also operate(d) on regional frequencies. Because they were within a certain distance of the dominant or primary Regional station operating on the same frequency in another city, they were required to sign off at local sunset.
Some Regionals that operated daytime only (D) later constructed directional antennas and were licensed to operate with a directional antenna (DA-N) at night with reduced power. WDOE, Dunkirk, for example, operates on 1410 with 1 kw day and 500 watts DA-N to protect KQV 1410 in Pittsburgh (which has a brutal directional pattern at night, despite being one of the earliest AM stations in America.)
The FCC years ago loosened the Rules allowing more stations on Regional Channels to operate at night with directional antennas, some with more restrictive patterns, reduced power or both. WXRL, directional at all times, (DA-1), actually increases power at night, but operates with a more restrictive night time pattern (DA-N.)
The Local Class 4 stations operate(d) on 1230, 1240, 1340, 1400, 1450 and 1490, at first with 250 watts, later by FCC decree with a combination of 1 kw Day/250 watts Night or 500 Day/250 Night. Now, Class 4s operate with 1 kw day and night. (In this writer's view, adding to the cacophony of the AM band at night.)
That's a thumbnail sketch. Only matter of time before Fybush or Savage add the details, exceptions and coloration.