Maintenance
Coaxial RF Power Standards Instruction and Service Manual
5-7
Figure 5.5
Location of Bias Adjustment
4.
To adjust the DC bias voltage, locate the small hole in the Thermistor Mount casing near
the back. Remove any cal void stickers if necessary. Remove the plug using a 5/64” Allen
wrench
5.
Using a small tip slotted screw driver, turn the Bias Voltage Adjustment. CCW will increase
the bias the voltage, CW will decrease it. This must be done very slowly. Only turn the
adjustment screw a quarter turn at a time. It will take the bias voltage up to half an hour
to settle after one quarter turn adjustment is made.
6.
Once the Bias Voltage has been adjusted to 2.45 V, replace the plug in the Bias Voltage
Adjustment access hole.
Calibration Factor
This test characterizes the calibration factor of the Working Power Standards (F1125, F1130, and
F1135). The Working standard is characterized from the SENSOR port using a Reference Power
Standard (M1125, M1130, or M1135). This procedure can be automated using SureCAL
Automated Metrology Software.
1.
Replace the top cover on the Working Power Standard. It should be fully assembled for the
rest of the calibration.
2.
Connected both the Reference and Working Power Standards to an instrument with a
compatible heater control circuit and a DC Substitution Power Bridge (TEGAM 1806(A))
(see “Connecting RF Power Standards” in Chapter III Operating Instructions). Make sure
both standards have been warmed up for at least two hours.