Viking Drive Pot                 Modification  

                 Here is the problem, the Viking series uses a puny 4 watt pot to control drive to the multiplier stage.     The pot circuit is a voltage divider and consumes power. The pot gets hot, ages from the heat, and then opens .

       R-51 location

   Not much room for a replacement of larger wattage.

     There is a spare hole in the front panel above the original drive pot. My plan is to mount a large man sized 5K, 10 watt pot in this hole and to put a rotary switch in the original hole. The new pot would hold a bracket of power resistors wired in series , the rotary switch would select the correct tap on the power resistors . Due to the size of the housing the larger pot would not fit in the lower hole and by mounting the pot a little higher cooling is enhanced.

     Assembly ready for mounting , shown are the power resistors, a large He Man sized 5 K, 10 watt pot and the rotary switch.The bracket is supported by the new 10 watt pot. The hole that the original drive pot is going to be the
new home for the rotary switch.

     Tabs were bent on the bracket edges so that the panel would stay in place once the pot mounting nut is tightened. The tabs "bite" into the pane.
   

      A terminal mounting board was used to hold the power resistors.

       Most of my junk box resistors have short leads, resoldering short bus wire leads to the resistor solves the problem.

          This will not burn up.