TM 11-6625-2781-14&P-2
ERRATA
n. Adjust the LOG REF LEVEL controls so that the maximum signal amplitude is exactly on the -70 db graticule line.
Rotate LOG REF LEVEL control seven steps in the clockwise direction. The amplitude of the signal should
increase in increments of one division per 10-dB step. (See Figure 4-2.) Adjust VERTICAL GAIN to place
maximum signal amplitude exactly on LOG REF (top) graticule line (Figure 4-2).
p. Repeat steps n and o to obtain optimum adjustment of VERTICAL GAIN (increments as close as possible to one
division per 10-dB step). Only slight readjustment of the VERTICAL GAIN should be necessary.
4.17. AMPL CAL Check for Linear Sensitivity Accuracy
4-18. In the LINEAR display mode the vertical display is calibrated in absolute voltage. For LINEAR measurements the
LIN scale factors on the left side of the CRT and the blue color-coded scales of the LINEAR SENSITIVITY controls are
used. The signal voltage is the product (note lighted ' x' lamp) of the CRT deflection and the LINEAR SENSITIVITY control
settings. It is usually most convenient to normalize the LINEAR SENSITIVITY vernier by setting it to' I' (blue scale).
a. Set the LOG/LINEAR switch to LINEAR. Set LINEAR SENSITIVITY to 1 mV/div. Since the 30 dBm calibrator
output is 7.1 mV (across 50 ohms), the CRT deflection should be 7.1 divisions.
b. Adjust AMPL CAL on 8553B for a 7.1 division CRT deflection, if necessary. (The LINEAR display is more
expanded than the compressed LOG display, so adjustment of the AMPL CAL control can be made with more
resolution in LINEAR without noticeable effect on the LOG calibration.
The analyzer is now calibrated for the LIN display mode.
4-19. AMPL CAL Adjustment (RF Section)
a. Set LOG REF LEVEL to 30 dBm.
b. Adjust AMPL CAL so that the signal amplitude (-30 dBm) is exactly on the LOG REF (top) graticule line of the
CRT.
The analyzer is now calibrated for both the LOG and LIN display modes.
NOTE
If measurements will be done primarily in LINEAR mode, perform the procedures in paragraph 4-
4-20. Front Panel Checks
4-21. Set controls as follows:
RANGE MHz ...........................................................................................................................................................0-110
SCAN WIDTH ................................................................................................................................................ 0-110 MHz
SCAN WIDTH PER DIVISION.............................................................................................................................10 MHz
BANDWIDTH ........................................................................................................................................................10 kHz
LOG - LINEAR ......................................................................................................................................................... LOG
LOG REF LEVEL .............................................................................................................................................. - 10 dBm
Perform Front Panel Checks listed in Table 4-2.
B-29/30
