[AMRadio] PC-mount 5-pin tube sockets?


D. Chester k4kyv at charter.net
Fri Jan 12 14:50:38 EST 2007


                I'm restoring and converting a Gates BC-1T transmitter which 
has a seriously
            damaged RF driver PC board.  I'm making a custom-etched 
replacement board, and
            changing it to the 807 version while I'm at it.  I've got all 
the parts
            except for any pc-mount 5-pin tube sockets for the 807 tubes... 
anyone have two?

            Steve WD8DAS


      Although I'm not standing right here looking inside mine right now, 
I'm pretty sure the board uses conventional 5-pin ceramic tube sockets, the 
kind with the metal mounting ring, mounted on the PC board.  The screw holes 
also accomodate the Millen 807 shields, and wire is used to connect the tube 
pins to the circuit board traces.

      Maybe the original 6BG6 sockets were the PC-board types.

      If I were going to replace the board, instead of etching a new PC 
board, I would use a piece of aluminium sheet cut to the same size, and use 
standoffs and terminal strips for the wiring, and use conventional metal 
chassis type construction.  Tubes-on-PC board construction is poor design 
and nothing but trouble.

      After I put my BC1-T on 160, I replaced the bakelite grid coil with a 
piece of air core inductor stock (Airdux or Miniductor) that I happened to 
have on hand.  It is the same physical size as the original coil, and has 
just exactly the number of turns needed to resonate on 160.  My grid drive 
increased from maximum 85 mills to the 833A's to 155 ma (plate off) and 
135ma (plate on at high power), and neutralisation was more complete.

      The 833A final was more stable after I altered the wiring so that all 
components in the driver plate/PA grid circuitry in the rf section were 
grounded to one common point on the chassis, instead of the way Gates did 
it, using the nearest convenient grounding point for each component.

      Don k4kyv

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