[Elecraft] 500 kHz Receive Operation With the KX1

[Doug Faunt N6TQS +1-510-655-8604]

   From: "Ron D'Eau Claire" <ron at cobi.biz>
   Date: Wed, 10 Jun 2009 16:25:49 -0700
   Content-Language: en-us

   That's a great recording, John! It's a great service to those who want to
   hear what sort of chaos reigned at the height of CW on the high seas. That
   was in the 60's and 70's when maritime trade was really booming in the
   Post-War world.  

   Wonder how many Hams today who sweat filters to clear out all the QRM can
   copy all of them at once? (IMHO, all the different tones and keying make it
   a lot easier than listening to the sterile sigs on the bands today.)

   Trivia question for you CW buffs (except John. He knows the answer!)

   What transmission mode was used for all emergency calls on 500 kHz? 

   Hint. It was *not* A1 (CW). 

   Ans: The MF transmitters were amplitude modulated (A2 or MCW) so their
   signals could be read on a receiver lacking a BFO. Lacking a BFO? Well, up
   until after WWII, it wasn't uncommon to find the "backup" or emergency
   receiver on a ship was a common crystal set! MCW was only required for
   emergency communications, but many Radio Officers fired up the modulator
   anyway for a more 'distinctive' sound when received with a BFO. 

   You may now retune your ears for modern, pristine, clean keyed, CW with
   dulcet tones. (Sort of like swapping distilled water for a fine wine to me,
   but that's progress ;-)

Actually, until the late 60's, in an emergency, "Mode B" was still
legal on 600 meters, at least internationally.  Mode B is spark.  

And that crystal set was REQUIRED by some authorities.

73, doug