[Milsurplus] Emergency Keyer Morse SOS Error (AN/ARA-26)

[Mike Morrow]

I've been examining an interesting little unit, a KY-65/ARA-26.  It was used
with AN/ARC-8, -21, -65, and -58 HF sets on USAF aircraft to automatically
send combinations of long dashes, SOS's, and/or the last four digits of the
aircraft's serial number in emergency situations.  Motor-driven mechanical
code wheels are used to actuate keyer contacts.

All who have a basic or better understanding of Morse practices knows that
SOS is always sent as one character, not as separate S, O, S characters.
But guess what...the KY-65 sends S O S (separate characters, not the correct
single character).   That's a pretty odd mistake to be designed into such a
unit.

I don't have the BC-778 or AN/CRT-3 lifeboat sets, but I wonder if their
mechanical code wheels also reflect this error.  Maybe the mechanical design
people had seen too many movies, where the SOS prosign is almost universally
incorrectly sent.  (I've only seen one movie, made 25 years ago about the
Titanic, that got it correct, and included a pretty good representation of
the sound of a spark-gap transmitter to boot.)

73,
Mike / KK5F