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f.
Replace tube V203.
g.
If no other alignment is required, install the Model 75D in its
cabinet (par. 4.12).
4.9
OSCILLATOR-DETECTOR ALIGNMENT.
Note:
See Test Points and Waveforms drawing at back of book.
a.
The internal controls used to align the oscillator-detector are shown in
Figure 11, Pg.83. When the Model 75D is removed from its cabinet, the
controls are accessible.
After the required alignment procedures are
completed, reassemble the Model 75D.
b.
Oscillator Alignment (L205).
(1)
Test equipment:
RF Voltmeter Type 92(Boonton Electronics Corporation)
or equivalent.
(2)
Procedure:
a
Remove the Model 75D cabinet (par. 4.12).
b.
Adjust the Model 75D front panel controls in accordance with
Table 4.
Co
Adjust the rf voltmeter to measure approximately 0.3 volts.
d.
Connect the voltmeter probe between the LO TEST terminal
ground and binding posts on the Model 75D front panel.
e.
Loosen the locking nut on internal control L205 by turning
counterclockwise (ccw).
f.
Adjust L205 for a maximum voltage indication on the rf voltmeter.
g.
Tighten the locking nut on L205 by turning clockwise (cw).
c.
Detector input Alignment (LI 01).
(1)
Test equipment:
RF Voltmeter Type 92 (Boonton Electronics Corporation)
or equivalent.
(2)
Procedure:
a.
Remove the cabinet.
b.
Adjust the Model 75D front panel controls in accordance with
Table 4.
c.
Set the MULTIPLY C switch to .1 .
d.
Set the DIVIDE G/MULTIPLY R switch to 10.
e.
Zero*balance the bridge as described in paragraph 3.5.
f.
Advance the CAPACITANCE control to 1000 pF on the dial.
g.
Adjust the rf voltmeter to measure approximately 0.01 volt.
h.
Connect the rf voltmeter probe between the TEST HI and ground
binding posts on the Model 75D front panel.
i.
Loosen the locking nut on LI01 by turning ccw.
j.
Adjust LI 01 so that the rf voltmeter pointer deflects downscale
and indicates < 5 mV.
k.
Tighten the locking nut on LI01 by turning cw.
l.
Remove the rf voltmeter.
75 D
b-370
63
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