the circular name plate says:
   KY-129/SAT-2
KEY TELEGRAPH
L. L. ROWE CO. 40064
SERIAL MFR-52115

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Well, that gives it away.  The AN/SAT-2 is an infrared transmitting set used for "covert" line-of-sight transmission from ship to ship at night.  Must be the key, which is usually what a KY-xxx.
 
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     Ship-to-ship generally meant using a specially-fitted searchlight (I believe it was about 12" in diameter), but because the searchlight was directional it had to be aimed.  If I recall, there may have been a dome-shaped infrared beacon mounted on the mast of the ship for non-directional transmission but the range would have been much shorter.
 
    Infrared transmission would have been used under conditions of absolute radio silence AND complete darken-ship conditions.  Of course, if the "other guy" had radar there wouldn't be much point 'cuz he'd know where you were, anyway.     :-)
 
    My guess is that it was developed in the 1940s or early 1950s but the AN/SAT-2 was still installed on Navy ships as late as the 1960s.  We had it on USS BELMONT (AGTR-4) but to the best of my knowledge it was never used except *maybe* during Underway Training at GITMO, and then only because it was on a check list ("Does such-and-such work?"   "Yep.").
 
    Those brass boxes with fitted covers are **SO** Navy.........     ;-)
 
73,
 
Paul, K4MSG