User Cal Factors Procedures
6-18 PN: 10585-00001 Rev. P ML2437A/38A OM/PM
Depending on the amount of factory calibration data stored in the sensor, there can be up to
10 user-defined cal factor tables. A “user” cal factor table consists of up to 90 frequency/cal
factor data pairs for sensors up to 40 GHz or 110 frequency/cal factor data pairs for sensors up
to 50 GHz, plus a 7-character identity text string. User cal factor tables are fully interpolated,
and can be used to apply correction for attenuators placed in front of the sensor. In this
situation, determine the attenuation factors and use them in addition to the Factory cal
factors. The number of frequency/cal factor data pairs in the factory defined table depends on
the sensor being used.
The cal factor tables for a particular sensor are not maintained by the meter, but are held in
the sensor. This means that when moving a sensor (perhaps with an associated attenuator or
calibration record) from one meter to another, the calibration stays valid. It is not necessary
to re-setup the new meter.
The first time a sensor is used with the ML243xA, a slight delay may be experienced when
the sensor is first plugged in. This is caused by the firmware preparing the sensor to accept
user cal factor tables. After first initialization, user cal factor tables will have only a single
entry at 50 MHz, 100 %.
Cal factor tables are accessed through the Sensor > CalFactor > USE TABLE front panel
menus (Chapter 4), or through GPIB commands.
Example Procedure
Use the key sequence Sensor > Cal Factor > EDIT to get to the table edit menu. Use the
TABLE key to select the table, then the EDIT key to edit that table. Press the INSERT key to
enter frequency and cal factor data pairs.
For example, in order to enter the frequency/cal factor pairs 1 GHz @ 100 %, 2 GHz @ 101 %,
3 GHz @ 98 % and 4 GHz @ 98 %, step through the keys in the following sequence:
FREQ, 1, GHz.Entr
FACTOR, 100, %
FREQ, 2, GHz. Entr
FACTOR, 101, %
FREQ, 3, GHz. Entr
FACTOR, 98, %
FREQ, 4, GHz. Entr
DONE
The frequency/cal factor pairs can be entered in any order. Each time a new frequency is
entered, a new data pair is formed. As the data pairs are entered, they are sorted into
frequency ascending order.
Readout Mode
In Readout mode, the bottom text line in the Status box indicates what type of calibration
factors are being used. At any time, if anything other than the factory supplied cal data is
applied, the Status box display shows a warning ‘*’ sign on the Cal Factor line to show that
non-standard calibration is being applied. For example:
Note
A * in the displayed status box by the Cal Factor indicator, signifies User Cal
Factors are active. User Cal Factors are maintained in the sensor.
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