This microphone was purchased from a TV studio liquidation auction.  I have subsequently tested it with a Sound Devices recorder.

The K3-U preamp works great.  Switches are in working order and 3 stage High Pass Filter works.  Some costmetic blemishes due to vintage condition.  In order to operate the preamp you'll need a PX23, EPX23, or V 23 PX camera battery (5 , 6 V)  MKE 2-3 condenser microphone also works and is tested.   I only have one working battery and it is not included.  Batteries can be purchased for $11.95 on Amazon.  

The ME80 Sennheiser shotgun microphone module also works great!  Sounds very clean when plugged into a Sound Devices recorder.  It is super directional, as you might imagine.

Please take a careful look at the photos from all sides.  This is a true frankenstein microphone that looks pretty beat up.  If you close your eyes though you'll love the way it sounds!  See photos from all sides for condition