Today, I finally have an answer, in the text of the CRTC application by CIAO in Brampton, Ontario, to switch to a single tower non-directional configuration now that Windsor has left 540.
530 kHz is a unique frequency, because it is adjacent to the NAVTEX maritime weather transmissions on 518 kHz. Due to this adjacency, the International Telecommunications Union ("ITU") restricts the maximum transmitter power to 1 kilowatt day and 250 watts night. Our broadcast consultant approached Industry Canada to ask if it were possible to negotiate higher domestic daytime power by coordination with the FCC, and/or whether a higher night power limit could be broached at the World Administrative Radio Conference (ITU-WARC). In response to that request, Industry Canada indicated that there was no appetite to pursue such a request.
To make the most of that limited power, they are building a 225.6 metre (nearly 750 feet) tower.
Until an hour ago, I had not realized that CIAO is the former CHIC, home of the famous All-Female Air Staff of the late 1960s. The CRTC application quoted above indicates they are still at the same transmitter site a half century later. At one time, they were running 5000 watts out of 10 towers there, not on 530 obviously, as that was long before 530 was added to the Broadcast Band.
