[Boatanchors] [Milsurplus] Unknown coil

[Michael A. Bittner]

I may not have been clear due to a couple of typos in my question which I have corrected herein.  In any case, I know how variometers work and their history.  The question was "what unit was this coil originally meant for?"  ARC-???, BC-???, possibly a ham transmitter, whatever?
  ----- Original Message ----- 
  From: Michael A. Bittner 
  To: milsurplus at mailman.qth.net ; arc5 at mailman.qth.net ; ArmyRadios at yahoogroups.com 
  Cc: boatanchors at puck.nether.net 
  Sent: Wednesday, May 30, 2012 4:57 PM
  Subject: [Milsurplus] Unknown coil


  Can anyone help me identify what unit was this coil originally meant for?  It is 2-inches in diameter by 2.25-inches long and is marked L-107.  It has a coupling coil inside that can be rotated for minimum to maximum coupling via the shaft that projects out at one end at a 45-degree angle.  Its rugged, quality construction suggests a military unit of some kind. 
  https://www.dropbox.com/gallery/56278480/1/L-107?h=9e44f3 

  Please click on the pictures for full size views.  Mike, W6MAB