Fig. 6-41. Typical equipment setup to check response flatness, sensitivity, frequency calibration and phase lock operation.
h. Move the 50 Ω termination to band B RF INPUT con-
37. Adjust Band A Mixer Balance--Check
nector, switch the band selector to B and set the DISPER-
Amplitude of Spurious Signals from Internal
SION to 10 MHz/div.
Sources
i. Adjust the GAIN control for 1 division of noise, then
a. Equipment setup is shown in Fig. 6-40.
tune through the band B frequency range checking for spuri-
ous signals whose amplitude exceeds 2 noise level.
b. Connect a 50 Ω termination to band A RF INPUT con-
nector. Switch the band selector to A.
j. Move the 50 Ω termination to band C RF INPUT con-
nector. Set the band selector to C.
c. Adjust the GAIN control so noise amplitude is about
1 division.
k. Check through the frequency range of band C for
spurious signals with amplitudes that should exceed 2
d. Tune the RF CENTER FREQUENCY to the low end of
noise level.
the dial against the stop. At this center frequency setting
with a dispersion of 2 MHz/div, a local oscillator feedthrough
38A. Check Dial Accuracy, Analyzer Sensitivity
spur should be visible on the display.
and Local Oscillator Phase Lock Operation
e. Tune the RF CENTER FREQUENCY to center the feed-
through spur, then decrease the dispersion to 1 MHz/div.
NOTE
Since signal generators with calibrated attenuators
f. Adjust C14, C16 and R13 (band A mixer, see Fig. 6-39)
are required to check sensitivity, dial accuracy
to minimize the amplitude of this feedthrough spur over the
can be checked by the same instruments, provided
5 MHz dispersion window.
the signal source has an accuracy within 0.1%
g. Check through band A frequency range for spurious
at the dial check points. The signal generatars
signals. Amplitude of any spur with the exception of the local
listed in Table 6-9 may be used if their accuracy is
oscillator feedthrough signal must not exceed 2 n o i s e
checked near each dial check point, by a frequency
amplitude. If a spur appears at approximately 37.5 MHz,
counter or by the beat frequency indicator against
readjust the mixer balance.
some accurate reference frequency.
6-40
