The first 50-kilowatt transmitter and 640 foot tower at Hornby, Ontario (west of Toronto) was built in 1937 for the new CBL (formally CRCT). In 1948, in what was possibly the first time anywhere, two 50 kW stations were put into a single 5/8 wave vertical tower (antenna) when CJBC - 860 kHz moved to the transmitter site (where it still broadcasts from). The current tower (650 feet) was placed at Hornby in 1991. At the base of the tower is a single small ceramic insulator supporting ten's of thousands of tons of antenna and guy wires. There is an underground radial ground system of wires approximately 3 degrees apart. A large diesel generator is the backup system for a steady signal. There are still rooms and a studio in the basement "bomb shelter" built in the 1950's. This allowed staff to continue broadcasting in the event of nuclear war.

The original building had also housed Continental 317C Transmitters, manufactured and installed by Continental Electronics in 1975. They have been replaced by new Nautel 50kW XR50 Solid State AM Transmitters which were installed in January 2007. The only other equipment added by CHWO was an OPTIMOD 9200 audio processor to provide a loud and clean sound at the transmitter. It transmits in an omni-directional pattern at 50,000 watts day and night.

AM 740 is on a "clear channel" (http://en.wikipedia.org/wiki/Clear_channel). These channels can be found on the frequencies 540, 640-780, 800-900, 940, 990- 1140, 1160-1220, and 1500-1580 kHz. These are typically populated by the 50,000 watts powerhouses. On each frequency there are usually only two or three of these stations across North America making DXing them fairly easy. Most of the clear channels also have a few lower power stations but they are not much of a problem unless one happens to be near your location. Old timers will remember when clear channels really were clear and had the only powerful signal.

For more information, check out these sites on CBL/CHWO Transmitter Sites & History:

• June 27, 1999, CBL 740 leaves Hornby for FM.
• The Hammond Museum of Radio's goodbye to CBL 740.
• A history of CBL 740.
• Wikipedia on CHWO and the former CBL AM now CBLA-FM.