[MRCA] FS: Chelsea Merchant Marine Radio Room Clock WW-II Vintage

[Mike Morrow]

But Mike, the prosign ...---... was never based on the letters SOS.  It was proposed by Germans in 1905 only because of its very distinctive sound (when sent correctly) that stands out from all the other characters and prosigns that were being used in international Morse telegraphy.  And it still does, though one will never hear it used again.

There are audio recordings of the Morse traffic associated with the fire, flooding, and sinking of the Dutch cruise ship MS Prinsendam on 10-04-1980 at

   https://archive.org/details/SosMsPrinsendamOctober41980

At the top pf the page you can select and play MP3 file number 2 to hear the actual initial 500 kHz distress call from the Prinsendam, radio call PJTA.  You'll hear first the 12 auto-keyed four-second dashes sent for one minute from PJTA to activate the auto-alarm receivers of any ship stations that can hear PJTA.  Next comes the SOS SOS SOS DE PJTA PJTA PJTA followed by the description of the vessel, nature of distress, number of people on board, location, etc.

It's interesting that, strictly speaking, that SOS was sent incorrectly as the word SOS, instead of the correct ...---... prosign.  The Dutch radio officer Jack van der Zee (Jack of the Sea!) defied his captain and sent the distress call without permission.  He was later awarded the very highly-regarded Knight of the Order of the Netherlands Lion by Queen Beatrix for that.

In unrelated areas, most of the common devices that automatically sent ...---... like the SCR-578-* and the AN/CRT-3 "Gibson Girls" and the many models of commercial maritime lifeboat station, the distress prosign is sent correctly as ...---... with one exception.  The USAF used the KY-65/ARA-26 keying unit with post-WWII MF/HF liaison receiver-transmitters AN/ARC-21, AN/ARC-65, and AN/ARC-58 to send SOS (from a metal cam wheel) along with an aircraft ID number (set for each aircraft by breaking off teeth on a plastic disk).  The KY-65 keys the distress signal incorrectly as ... --- ... (SOS)!

The only movie in which I've heard ...---... sent correctly is the 1979 "S.O.S. Titanic" during opening credits.  Although the title's use of "S. O. S." is absurd, the audio has correct ...---... keying along with accurate sound that a spark transmitter would make in a receiver's headphones.

Mike / KK5F

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Regardless, it still seems like a derivative of SOS. 

73  Mike B. Feher, N4FS

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Because it is sent as one special signal, without the spacing for individual letters.

73, Meir WF2U
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Hey Mike, if ...---... is not SOS, what is it? 73 - Mike 

Mike B. Feher, N4FS

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Only after that would the unique ...---... (not SOS!) distress signal be
sent. 

Mike / KK5F