* The 6C4 Phase splitter In the space cramped space rigs ( Ranger, DX-100, Apache, etc. )  may be directly replaced ( gate for grid, source for cathode, and drain for plate )  with no component changes with a tiny ( TO-92 ) 1 watt 500 volt N-Channel Depletion Mode MOSFET Triode, a Supertex  Inc. Type # LND150N3  <<< specs >>>  mounted under the chassis.  These MOSFET's are Transconductance devices very identical to their older tube counterfellows.       <<< Mouser >>>  carries this MOSFET for 51 Cents each. To locate sellers for these MOSFET's go to Google and type in part # and "  price* ".