B+K precision 2165A, Instruction Manual, Page: 15 / 28

15
CALIBRATION
Vertical Calibration (Models 2625 and 2630)
Prior to calibration, ensure that all input attenuators (
14 ) are
released. The spectrum analyzer must be in operation for at
least 60 minutes prior to calibration. Switch
VIDEO
FILTER ( 11 ) to OFF position. Set BANDWIDTH ( 10 ) to
400 kHz. Set SCANWIDTH ( 15 ) to 2 MHz/div.
Connect calibrated RF signal of –27 dBm ±0.2 dB (10 mV)
to the spectrum analyzer input (
13 ). The frequency of this
signal should be between 2 MHz and 250 MHz. Set the
center frequency to the signal frequency.
A: A single spectral line (–27 dBm) appears on the screen.
The spectral line maximum is now adjusted with the Y-POS.
control ( 12 ) and placed at the top graticule line of the
screen. All input attenuators switches have to be released.
The following adjustment is only necessary for service
purposes and if the check of this settings shows deviations
of the correct settings. The y-ampl. control is located on the
XY-PCB inside the instrument. In case any adjustment of
the vertical amplification is necessary, please refer to the
service manual.
B: Next, the generator signal must be switched back and
forth between –27 dBm and –77 dBm, and the Y-AMPL.
control adjusted so that the spectral line peak changes by 5
divisions in the vertical direction. If this results in a change
of the Y-position, the calibration outlined under
A has to be
repeated. The calibrations A and B have to be repeated until
an ideal adjustment is achieved.
Finally, the operation of the input attenuators (
14 ) can be
tested at a level of –27 dBm. The spectral line visible on the
screen can be reduced in 4 steps of 10 dB each by activating
the attenuators incorporated in the spectrum analyzer. Each
10 dB step corresponds to one graticule division on the
screen. The tolerance may not exceed ±1 dB in all
attenuation positions.
Vertical Calibration (Models 2615A and 2620A)
Prior to calibration, ensure that all input attenuators (
14 ) are
released. The spectrum analyzer must be in operation for at
least 60 minutes prior to calibration. Switch
VIDEO
FILTER ( 11 ) to OFF position. Set BANDWIDTH ( 10 ) to
250 kHz. Set SCANWIDTH ( 15 ) to 2 MHz/div.
Connect calibrated RF signal of –27 dBm ±0.2 dB (10 mV)
to the spectrum analyzer input (
13 ). The frequency of this
signal should be between 2 MHz and 250 MHz. Set the
center frequency to the signal frequency.
A: A single spectral line (–27 dBm) appears on the screen.
The spectral line maximum is now adjusted with the Y-POS.
control ( 12 ) and placed at the top graticule line of the screen.
All input attenuators switches have to be released.
B: Next, the generator signal must be switched back and
forth between –27 dBm and –77 dBm, and the Y-AMPL.
control adjusted so that the spectral line peak changes by 5
divisions in the vertical direction. If this results in a change
of the Y-position, the calibration outlined under
A has to be
repeated. The calibrations A and B have to be repeated until
an ideal adjustment is achieved.
Finally, the operation of the input attenuators (
14 ) can be
tested at a level of –27 dBm. The spectral line visible on the
screen can be reduced in 4 steps of 10 dB each by activating
the attenuators incorporated in the spectrum analyzer. Each
10 dB step corresponds to one graticule division on the
screen. The tolerance may not exceed ±l dB in all attenuation
positions.
Horizontal Calibration (Models 2625 and 2630)
Prior to calibration ensure that all input attenuators switches
(
14 ) are released. The spectrum analyzer must be operated
for at least 60 minutes prior to calibration. The VIDEO
FILTER push button ( 11 ) must be in OFF position. Set
BANDWIDTH ( 10 ) to 400 kHz. Set the SCANWIDTH ( 15 )
to 50 MHz/div. After the center frequency is set to 250 MHz,
a generator signal must be applied to the input. The output
level should be between 40 and 50 dB above the noise.
C: Set generator frequency to 250 MHz . Adjust the peak of
the 250 MHz spectral line to the horizontal screen center
using the
X-POS. control ( 16 ).
D: Set the generator frequency to 50 MHz . If the 50 MHz
spectral line is not on the second graticule line from left, it
should be aligned using the
X-AMPL. control ( 17 ). Then the
calibration as described under C should be verified and
corrected if necessary.
The calibrations
C and D should be repeated until optimum
adjustment is achieved.
Horizontal Calibration (Models 2615A and 2620A)
Prior to calibration ensure that all input attenuators switches
(
14 ) are released. The spectrum analyzer must be operated
for at least 60 minutes prior to calibration. The VIDEO
FILTER push button ( 11 ) must be in OFF position.