First built by Canadian Marconi in 1942, the thirteen tube CSR5 general coverage superheterodyne receiver was capable of receiving CW or AM signals in the 80 khz to 30 Mhz bands. These receivers were used to receive the fleet broadcast or guarding the International or marine distress frequencies. The most notable feature, is the four position, selectable, IF band pass filter which helped to reduce interference. The RCN also modified all of the CSR5 receivers. In order to receive the 73.6 KHz fleet broadcast frequency, the "F" band (80 to 200 KHz) was calibrated 10 kHz lower than the dial reading. This frequency is still assigned to Maritime Command today.
First built in 1942 by the Marconi company, the CM11 was a transmitter
and receiver capable of operating in the 375 KHz to 13.8 MHz bands with
the exception of the broadcast band although LF was never sent from ships
at sea. It was rated for 100 watts for CW, 70 watts on MCW or 30 watts
on AM. Without a doubt, it was the workhorse of the radio office. The internal
antenna tuner could match any antenna that was 5 to 750 ohms resistive
between 515 KHz and 13.8 MHz. Unfortunately, at 478 pounds, the CM11 wasn't
very portable, but if one had to, horseshoes could be forged on the cabinet,
something that can't be done with today's commercial equipment.