Class B AMs that are non-directional at night

[semoochie]

David posted a link to the entire NARBA details, and the facilities that were allowed to existing stations in 1940. There were scores of stations, the Class III-As and III-Bs, that were allowed 1000 or 500 watts nondirectional at night. Most opted to go to 5000 watts directional at night. BTW, a little known fact is that Class III-As were not all 5000 watts night, 1000 watts was a perfectly acceptable night power for III-As. Also, all 5000 watt night facilities were not III-A, in fact, many were III-B or even just Class III if the NIF was higher than 4 mV/m or received more than 200 uV/m 10% interfering signals from other stations. As I recall, it was assumed in the past that not more than one station would interfere at a time at the 10% skywave level, and when there were just a handful of fulltime stations on each Regional Channel, it was a reasonable assumption. When the FCC changed the skywave calculations and included first adjacents, it became clear that many stations, many of the old line III-As, were not III-As and many not even III-Bs when the new calculations were made. Directionals were few and far between back then. It seems like before the postwar boom, there were only about 40, mostly those Class III-As that went to 5000 watts night. They weren't well enough understood in the NARBA paper linked to detail them in the document. There may have been appendices that weren't linked.

I'm a little hazy on that: Stations went forever but almost everyone was nondirectional. Why wasn't there more interference?

 

[Schroedingers Cat]

People had better radios and antennas. There were probably no more than 4 stations on at night within 1000 miles on each frequency, usually in different directions, in the early 1940s. There might have been 10 stations on each frequency total. It was not until after World War II that the number of stations began to increase greatly, and by the 1950s, many of these were daytime only. It was only when Class D stations were allowed PSSAs that things really got out of hand, and there were numerous cochannel stations that interfered.

The closest simulation would be the expanded AM band. You usually only get one or two at any particular time, usually one, and they are often hundreds of miles away. There are no daytime stations, any the vast majority are 1000 watts nondirectional. There are also no PSSAs on the expanded band.

 

[1L6E6VHF]

Two I know of (off hand, I'm sure I have some more I've forgotten about):

KKTY Douglas, WY on 1470 (a very strange freq. for a B omnidirectional at night!) 1000/500w U1 (they inherited this channel from KTWO when it moved from 1470 to 1030. KKTY - actually KWIZ then, I think, had been a daytimer on 1050)

WOAD Jackson, MS on 1300 5000/1000w U1. Actually have DXed this in MI. It's older than dirt and is the senior station on the frequency. I guess they just decided to resist the temptation to go 5kw and decided not to go directional.

Another oddity is WMAM 570 Marinette, WI. This is not (or no longer?) a B, but has been 250/100w U1 since it signed on in 1939. It was running 100w N decades before PSSA/PSRA, and it seems the FCC itself can't choose what class this station really is - sticking it with a "D" in the CLASS column in the database, yet describing it as having a waiver for "Local station on regional channel" (I take local station to be synonymous for class C).

(edit) Honorable mention: WQTT 1270 Marysville, OH. No, this station with 500w day and night is NOT omnidirectional at night, but while it has a very tight six-tower pattern by day, westward, its night pattern is with only two towers, southeastward. I'm thinking it may cover ten times the population at night that it covers by day.

 

[deepstblu]

Another special case: WEMG Camden NJ, 1000 day/250 night on 1310, and on the FCC books as a Class B. In the 1940s this station (then WCAM) was part of a three-way, three-city time share with what were then WCAP Asbury Park and WTNJ Trenton, all of them with power of 1000/500. Supposedly the FCC wanted to get rid of the time share badly enough to waive the minimum power rules for all three stations; Camden and Asbury Park each went full-time and stayed non-directional but dropped to 250 watts at night, while Trenton shifted to 1300 as a 250-watt daytimer. The other two (now WADB Asbury Park and WIMG Ewing) have gone directional with increased power, but Camden has never changed.