2 Service62 Keysight 53147A/148A/149A Assembly Level Service GuidePower Reference Oscillator Frequency CalibrationThe internal power reference oscillator is used to calibrate the Power Meter to thepower sensor head. This adjustment calibrates the frequency output of the powerreference oscillator to 50.0 MHz ±0.5 MHz.Equipment RequiredKeysight 53150A Microwave Frequency CounterKeysight 10503 series BNC (m) to BNC (m) Coaxial CableKeysight E9635A Type N (m) to BNC (f) AdapterSmall, non-metallic adjustment tool for slotted screw heads1 Turn off the Keysight 53147A/148A/149A, and disconnect the power cord.2 Remove the shroud from the Keysight 53147A/148A/149A (see “Removing theShroud” on page 96).3 Position the Keysight 53147A/148A/149A on its right side so that you haveaccess to the front panel and the left side of the main circuit board (seeFigure 2-2).NOTE – The instrument and the test equipment must be powered on for at least30 minutes prior to adjusting the power reference oscillator output. Thisallows the internal temperatures of the equipment to stabilize.– This procedure specifies the Keysight 53150A for measuring the frequencyoutput of the 53147A/148A/149A’s power reference oscillator. If the 53147A/148A/149A’s Frequency Counter is known to be in calibration (see “Test 1:Channel 1 Frequency Sensitivity” on page 31), you can use it in place of the53150A in this procedure.– Adjusting the power reference oscillator frequency may also affect the outputlevel of the oscillator. Therefore, after you adjust the frequency to 50.0 MHz ±0.05 MHz, always check the output level and adjust it, if necessary, asdescribed in “Power Reference Oscillator Level Adjustment” on page 66.
