Both receiver and transmitter stability are important when running the very slow visual CW modes. Here is an image of my drifting QRSS60 CW signal at 5 mW ERP during a very low power test with another station.
WG2XIQ QRSS60 CW. Painfully slow and not very stable (courtesy W5EST).
WG2XIQ CW on 474.5 kHz in Wisconsin at WH2XHY on a very good night (courtesy WD8DAS):
This is an image supplied by KL7L (ex-KL1X) of “AQC” (G3AQC, SK) of the first 137 kHz decode from Europe in Alaska “way back when”:
AQC at KL1X on 137 kHz – First EU -> KL7 reception (courtesy KL7L)
WSPR and JT9 are very common on 630- and 2200-meters. This image was supplied a few years back by David, VK2DDI. He was pointing out that the faint signal around 475.620 kHz was most likely me but during this sequence there wasn’t enough signal for a decode.