• Connecting Phototubes to the Board
  • Plug green signal cables into the connector on the phototube labeled "SIG"
  • Plug other ends of green cables into two of the inputs on the board
  • Connecting high voltage supply to divider box and the divider box to the phototube (again, double check that your high voltage is off before continuing with this step!)
  • Setting and Turning on High Voltage

  • Please note, it is possible to damage the tubes by running them at too high a voltage, so be careful during this step!
  • Set the power supply to the HIGHEST voltage required by all the phototubes you are using.  Note: DO NOT TURN ON HIGH VOLTAGE SUPPLY YET!
  • Use the voltage divider box to decrease the voltage that will be seen by the other (not highest voltage) tubes in your telescope
  • Example: you have three tubes which run at 1150V, 1250V and 1100V, respectively.  Set the supply to 1250V, and the voltage divider to -100V, 0V and -150V for the three tubes, respectively  
  • You are now ready to turn on your supply.
  • If your supply is a "Northeast Scientific" supply, set your supply to "STD-BY" and let the vacuum tubes warm up for one minute   (skip this step if your supply is a "Bertan")
  • Turn on your supply
  • Adjusting Thresholds of your Board

    Although the default threshold of 30mV is probably fine for more applications, you may wish to increase your  threshold if your tube has a high count rate at a low voltage (1000V) or decrease your threshold if it has a low count rate at a high voltage (1500V)
     
  • The procedures for adjusting the threshold are documented in the "electronics instructions"
  • Parts you will need : flat head screwdriver for removing top, board with power

  • available, digital voltmeter with probes, jewlers screwdriver 
  • Removing the top of the board housing with power off 
  • Reading threshold voltage (reads 10x actual threshold) as voltage between ground on PMT input connector and test point
  • Adjusting the blue potentiometer with jewler's screwdriver until you reach the desired

  • threshold (probably between 10 and 50mV)