The english text on the back of the card:
CHU time signals are transmitted continuously on 3330, 7335, and 14670 kHz, from individual vertical antennas located at 45(deg) 18' N, 75(deg) 45' W, with powers of 3, 10, and 3 kW respectively. An AM compatible mode (H3E, upper SSB with carrier reinserted) is used. Carrier frequencies, and the onser, frequency and phase of the 1 kHz tones whose beginnings mark the seconds are all controlled from a cesium frequency standard. A time announcement is made just before the start of each minute, in English and French. A computer-readable code (Bell 103 modem at 300 bps) is appended to seconds 31-39. Its decoding is described in Canada's Time Service, available from NRC.
Thank you for your report of reception on
The card came in a brown envelope like the ones Cuba uses, but without the appearance of having been left out in the rain. The reported frequency was not circled on the back of the card, and there was no reception date noted. An oddity with the envelope was this stamp providing the return address: "Return to PO BOX 1957 / BUFFALO NY / 14240".