Check out my collection of WWV QSL cards! Each one carefully marks my successful reception of the time signals broadcasted by WWV, the renowned time station operated by the National Institute of Standards and Technology (NIST) (and predecessor National Bureau of Standards (NBS)), across all verified frequencies: 2.5, 5, 10, 15, 20, and 25 MHz. Despite historical challenges with intermittent operation at 25 MHz, recent broadcasts have been more consistent. It’s been quite a journey meticulously logging and verifying each transmission.