J-38 "Navy" Morse Key

[Story]

Soooooooooo.... cleaning out the shop, came across a bunch of old telephones and telegraph keys. Turns out this one is something you Signal Corps types might like.

 

Being ignorant, I had to do a crash self-learning course. 

Quote

The J-38 was designed to be used with a Signal Corps radio/telegraph operator training set. The strange looking binding posts and shorting strap at the back of the key were used to connect a set of headphones to one side of the key ("tel") and the other side of the key ("line") to the training set. The effect was to put the key and headphones in series. Click here to see a description of the set up and key circuit (from War Department Technical Manual TM 11-432, February 2, 1942).

 

https://k6ix.net/J38Keys.html

 

The closest pre-existing threads I could find were

https://www.usmilitariaforum.com/forums/index.php?/topic/215435-training-for-victory-radio-book/#comment-1697859

and

https://www.usmilitariaforum.com/forums/index.php?/topic/171260-pre-ww2-field-radio-scr-288/#comment-1305951