[Elecraft] OT: possible ham operation in the region of415-526.5 Khz

[David Cutter]

Grimeton is planned to be on air Christmas Eve, 24 Dec at 0800 UTC on 17kHz. 
http://www.alexander.n.se/transmissions.htm  signing SAQ

I remember being woken at 3am by the 500kHz auto-alarm while off Western 
Sahara from an SOS in the English Channel.  So much for short distance !


David
G3UNA


> An interesting footnote for some of the newer Hams:
>
> Historically, the reason 500 kHz was chosen for emergency calling (SOS) 
> was
> that such a high frequency was considered of little use for long range
> communications. Back before WWI, "everyone knew" long range communications
> required lower frequencies and some of the most powerful shore stations
> operated at frequencies as low as 17 kHz. The whole plan for disaster
> communications at sea was to alert *nearby* ships to provide aid, so a
> higher frequency with its shorter range was ideal. All ships subject to
> SOLAS (Safety Of Life At Sea) rules were required to carry a calibrated
> radio direction finder in the wheel house to "home in" on a 500 kHz signal
> to locate a lifeboat or ship in distress.
>
> Along the same thinking, the local AM Broadcast band was put above the 500
> kHz frequency - roughly 550 to 1500 kHz - where high power stations would
> have a range of perhaps some tens of miles, the experts said, suitable for
> bringing newfangled "broadcasting" into local households. And, of course,
> those pesky "Amateurs" can have the frequencies above roughly 1500 kHz 
> (200
> meters) and will certainly never get out of their own back yards on such
> high frequencies.
>
> Fortunately, that was one more time when all the experts were wrong.
>
> Ron AC7AC
>