B. Set the band selector to B and set the DISPERSION to
1) Set the front panel controls as follows:
10 MHz/div.
10 MHz
RF CENTER FREQUENCY
MHz/DIV
DISPERSION RANGE
5 MHz/div
DISPERSION
20 dB
IF
ATTENUATOR
LIN
VERTICAL DISPLAY
5 ms
TIME/DIV
A
Band Selector
2) Apply the output signal from a signal generator
within the frequency range of band A, to the band A
RF INPUT connector.
3) Set the generator frequency and the RF center fre-
6) Check display flatness as per Table 6-8. 3 dB maxi-
quency to the frequencies that are listed in Table 6-7.
mum amplitude variation over 100 MHz window (50 MHz
Adjust the signal generator output attenuator and the
from RF center frequency). Maximum signal amplitude
Type 491 GAIN control for a signal amplitude of 6 divi-
with the MIXER PEAKING control before measuring flat-
sions.
ness.
4) Check band A display flatness by tuning the signal
7) Remove the signal from band B INPUT and apply
from the display screen left edge to the right edge with
the output from signal generators, that cover scales 4
the RF CENTER FREQUENCY control. (Frequency range +
through 6 frequency range, to band C Coaxial Mixer.
and -25 MHz of the RF center frequency.) Signal ampli-
8) Check response flatness through the frequency range
tude should not change more than 1.5 dB from its
of the Coaxial Mixer. Maximum amplitude variation over
average amplitude or 3 dB total.
100 MHz dispersion window must not exceed 3 dB. Adjust
MIXER PEAKING for maximum signal amplitude before
measuring flatness.
Applied Signal
RF Center
9) Replace the Coaxial Mixer with the Waveguide Mixer
Frequency
Generator Freq.
Adapter.
35 MHz
10 MHz-60 MHz
10) Apply the output from o signal generator, within
75 MHz
50 MHz-100 MHz
the frequency range of scale 8 and 9 through one of the
125 MHz
100 MHz-150 MHz
Waveguide Mixers and the 2 foot cable (with the BNC
175 MHz
150 MHz-200 MHz
connectors) to band C Waveguide Adapter.
225 MHz
200 MHz-250 MHz
11) Check response flatness for the frequency range
275 MHz
250 MHz-275 MHz
above 12.4 GHz. Maximum amplitude variation over 100
MHz dispersion window must not exceed 6 dB. Adjust
Mixer PEAKING for maximum signal amplitude before
5) Remove the signal to band A, RF INPUT and apply
measuring flatness.
a signal within the frequency range of band B to RF INPUT
6-38
