TM 11-6625-2781-14&P-2
Section IV
usually most convenient to normalize the LINEAR
h. Adjust VERTICAL GAIN to place maximum
SENSITIVITY vernier by setting it to "1" (blue scale).
signal amplitude exactly on LOG REF (top) graticule
line, Figure 4-2. Repeat Steps g and h to obtain
optimum adjustment of VERTICAL GAIN (increments as
a. Set the LOG/LINEAR switch to LINEAR. Set
close to one division per 10 dB step as possible).
LINEAR SENSITIVITY to 1 mV/div (1 mV x 1). Since
the -30 dBm calibrator output is = 7.1 mV (across 50
4-18. Ampl Cal Adjustment (RF Section)
ohms), the CRT deflection should be 7.1 divisions.
b. Adjust AMPL CAL on 8553B for a 7.1 division
CRT deflection, if necessary. (LINEAR display is more
a. Set the LOG REF LEVEL controls to -30 dBm (-
expanded than the compressed LOG display, so
30 + 0).
adjustment of the AMPL CAL control can be made with
b. Adjust AMPL CAL so that the signal amplitude (-
more resolution in LINEAR without noticeable effect on
30 dBm) is exactly on the LOG REF (top) graticule line
the LOG calibration.) The analyzer is now calibrated for
of the CRT. The analyzer is now calibrated in the LOG
both the LOG and LIN display modes.
display mode.
4-21. Set controls as follows:
4-19.
Ampl Cal Check for Linear Sensitivity
Accuracy
RANGE- MHz ................................ .................... 0-110
SCAN WIDTH ................................ .......... .0-100 MHz
4-20. In the LINEAR display mode the vertical display is
SCAN WIDTH PER DIVISION ........................ 10 MHz
calibrated in absolute voltage.
For LINEAR
BANDWIDTH ................................ .................. 10 kHz
measurements the LIN scale factors on the left side of
LOG-LINEAR ................................ ....................... LOG
the CRT and the blue color-coded scales of the LINEAR
LOG REF LEVEL ................................ .......... .-10 dBm
SENSITIVITY controls are used. The signal voltage is
the product (note lighted "x" lamp) of the CRT deflection
Perform tests in Table 4-2, Front Panel Checks.
and the LINEAR SENSITIVITY control settings. It is
4-4
