Not knowing the dates when KYW moved to Philadelphia, or when the "NARBA" was
ratified, I assume that the move of KYW occurred well before the "NARBA"? If
this is the case, how did the KYW pattern come to have such a deep null towards
WINS, which wouldn't have even existed at the time?


NARBA was signed in 1939 and was implemented in 1941. It was in 1941 when the
great AM frequency change occurred, and when stations in the same market could
be reduced to 40 kHz from 50 kHz spacing.

I believe the move of KYW to Philadelphia from Chicago occurred after two
stations were consolidated into one (KYW) in Chicago, but before the 1050 Class
II-B assignment in New York was agreed to.

However, before NARBA, 1050 was a U.S. de-facto Class I-A clear (KNX, Los
Angeles), and the ceding of 1050 to Mexico as a new Class I-A clear for that
nation, and the allocation (but not the construction) of a Class II-B to New
York would have been simultaneous with the codification of 1060 as a Class I-B,
in-fact, in Philadelhia and a similar station in Mexico City.

So, these changes could have been (and probably were) coordinated.

KYW's prior operation in Chicago, and its early operation in Philadelphia was
10 kW ND-U, on 1030.