Fig. 6-42. Typical equipment setup to check response flatness, sensitivity, frequency calibration and phase lock operation for band C.
c. Set the DISPERSION to 500 kHz/div and the RESOLU-
A secondary or alternate source of accurate fre-
TION control for a resolution bandwidth of 100 kHz (fully
quency markers is the combination of two calibra-
clockwise).
tion fixtures (Harmonic Generator 067-0594-00
and a 200 MHz Trap 067-0595-00) and a rela-
d. Adjust the GAIN control for an average noise ampli-
tively low frequency, accurate (at least 0.1%)
tude of one division. Center the IF CENTER FREQ and FINE
signal source such as a Time-Mark Generator (Type
RF CENTER FREQ controls.
184).
e. Tune the signal on screen with the RF CENTER FRE-
The harmonic generator will produce sufficient
QUENCY control. Reduce the signal amplitude with the
harmonic signal power, from the Type 184, to pro-
signal generator output attenuator control for an on-screen
duce frequency markers into the GHz range. The
display, then adjust the MIXER PEAKING control and sweep
200 MHz trap attenuates the IF feedthrough spuri-
rate for optimum signal amplitude. (Sweep rate 5 ms/div
ous response.
or slower.)
f. Calibrate the signal generator output, then adjust the
This procedure is divided into two steps, with step
variable output attenuator control on the signal generator
38B describing the dial check procedure using the
until the signal amplitude is two divisions (twice the noise
harmonic generator.
amplitude). See Fig. 6-44.
g. Check the total signal attenuation (in dB) below 0 dBm
a. Equipment setups are shown in Fig. 6-41 through 6-43.
as indicated on the signal generator attenuator dial. This
is the sensitivity of the analyzer for the RF center frequency
dial accuracy (step 38 B),
indicated. Check as listed in Table 6-9 under 100 kHz re-
b. Apply a frequency and amplitude calibrated signal,
solution. Sensitivity can also be checked for 1 kHz resolu-
tion, however, a very stable signal source is required at the
between -60 dBm and -30 dBm, to the appropriate RF
INPUT connector. Switch the Type 491 band selector switch
higher frequencies. Sweep speed must be rduced to 50 ms/
to the appropriate band.
div or slower to check sensitivity at 1 kHz resolution.
6-41
