Figure 1. Vhf amplifier 1A2AR2 calibration interconnection diagram.
(7) Remove RF cables from unit under test
VHF INPUT OUTPUT connectors.
(2) Insure that power supply panel (1A3)
MAINS switch is set to ON
(8) Connect vhf signal generator RF
OUTPUT connector to unit under test VHF INPUT
(3) Set sweep generator controls and
connector (fig 1 CONNECTION B)
switches as follows:
(9) Connect RF voltmeter to unit under test
(a) POWER switch to ON.
VHF OUTPUT connector
(b) MARKERS switches to OFF.
(10) Set vhf signal generator for 130 MHz at
(c) SWEEP setting to 170.
75 millivolt operation.
(d) MARKER setting to 170.
(11) Set RF voltmeter to 1000 millivolt scale.
(e) MARKER
WIDTH
(SIZE)
to
(12) Increase vhf generator frequency In
Midposition
10MHz steps (each setting at 75 millivolts) from 130
(f) RF FUNCTION to SWEEP.
MHz to 190 MHz (13) Observe that RF voltmeter
(g) SWEEP RATIO to Left position.
indicates 400 millivolts minimum for each setting
(h) RF ATTENUATOR to 0.
b. Adjustments
(i) SWEEP WIDTH to Maximum.
(1) Operate unit under test power supply
(i) SWEEP RATE to LINE.
panel (1A3) MAINS switch to off position.
(k) MONITOR to RF1
(2) Loosen captive screws securing test
matrix panel (1A2) to cabinet frame and open.
(I) MONITOR LEVEL to Midposition.
(3) Remove vhf amplifier subassembly from
(4) Set oscilloscope controls and switches as
panel by removing the two retaining screws
follows:
(4) Locate adjustment cap on bottom of vhf
(a) Power switch to ON
amplifier subassembly and remove
(b) VOLT/DIV control initial setting
(5) Operate unit under test power supply
.005; thereafter adjust as required.
panel (1A3) MAINS switch to ON.
(5) Set vhf signal generator for 130 MHz
(6) Adjust capacitor C13 to give fat
operation.
symmetrical response as noted In step a (6) above, with
NOTE
the required level noted in step a (13)
Vary vhf generator rf output level and
NOTE
frequency output (from 130 to 190
MHz) as required to achieve proper
If capacitor C13 is readjusted In step
oscilloscope presentation in step (6)
b (6) above, repeat steps a (3) to (13)
below.
(7) Operate power supply panel (1A3) MAINS
switch to off position
(6) Observe that oscilloscope trace is flat and
(8) Reinstall adjustment cap into vhf amplifier
symmetrical for sweep from 130 to 190 MHz as
subassembly
illustrated in figure 1.
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