The rf output of 1050 ESPN is directional, favoring the northeast. There is a
null toward Philadephia to protect 1060 KYW.


Actually, it is precisely the opposite.

The controllable null in KYW's pattern is towards 1050. This is the only case I
am aware of of a Class A station protecting a Class B station.

(KYW has a mimima, NOT a null, in its pattern towards the co-channel Class A in
Mexico. The depth of this minima is a consequence of the spacing of the array's
two towers).

1050 protects the entire U.S.-Mexican border, as was agreed to in NARBA.

(The two 48-state Class II-B stations on Mexican Class I-A clears were required
to operate 50 kW-U, DA-1, and both 1050 and 1220 do so; the two Alaskan Class
II-B stations granted by NARBA on Mexican Class I-A clears operate 5 kW-U, ND,
but one has been deleted).

1050 didn't exist before NARBA, and was granted 50 kW-U, DA-1, in New York, by
that treaty. (1220 was granted 50 kW-U, DA-1, in Cleveland, by that same
treaty).

KYW was moved to Philadelphia from Chicago, probably as a 10 kW-U, ND station.

1060 in Philadelphia would be mutually exclusive with 1050 in New York if KYW
didn't protect 1050, thereby establishing a defendable Class A contour towards
the NE (and 1050) for itself.