As you’ve got a live auction going I’ll PM you my thoughts on value.

Indeed, these sets were “wideband” by todays standards, and the technology of the time limited most communications to those frequencies below about 2 mhz (Just above the top of the present AM MW broadcast band, which was established during this period). If you can imagine global communications trying to fit within the space you would today allocate one or two local FM stations you can see why things had to change.

The problem was twofold. The transmitters might put out a signal over 100khz or more of spectrum, wiping out weaker signals for any local receiver. In addition, the passive “crystal set” receivers of the day could be made very sensitive (good at weak signals) or very selective (good at differentiating signals close in frequency) but not both. The main limitation on the range of your set above is the receiver used at the other end. To compensate, international telegraphy stations used enormous outputs – several Mw (Megawatts) being common. As you can imagine, this only added to the problem.

An excellent surviving example of an early telegraphy station is the Alexanderson station in Grimeton, Sweden, callsign SAQ. This is a true narowband station that still goes on the air throughout the year and is readily received in the UK. It does help that they can use NATO antenna arrays though:cool:.

Your posting has made me dig out a few old crystal sets and connect them to the HF antenna here. Daytime reception* connsists of my local BBC MW transmitter (2Kw, 12 miles away) and Droitwich on LW (500 Kw, ~150 miles away). At night I can receive most of the european longwave stations and a handful of additional mw signals – but nothing within 40 khz or so of my “local”, it bleeds over any adjacent signal.

*on a 1924 “Lowke Dane Tree” commercial set.