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(8)
If the above tests are satisfactory the instrument is serviceable and no
further attention is necessary. If, however, a servicing schedule calls
for checking of the Attenuator or recalibration of the Amplifier Divider
Assembly, proceed as follows:-
Attenuator Check:
4.6
(1)
Apply 480 MHz from the Signal Generator, at 10 mV r.m.s., to the
INPUT socket of the instrument.
(2)
Terminate the :- 100 (or
~
10) output socket with 50 ohms and connect a
digital counter to this output.
(3)
Switch on the power and set the SENSITIVITY switch to 10. 01VI.
(4)
Carefully reduce the input voltage from the signal generator
~ntil
the
counter just ceases to operate. Carefully adjust this input level to the·
threshold where correct counter operation is resumed, and note the exact
input level obtained.
(5)
Set the SENSITIVITY switch to 10. lV·, thus introducing a nominal 20 dB
of attenuation.
(6)
Increase the input voltage from the signal generator until the counter
once again just commences correct counting. Check that this input
voltage is 20 dB (±3dB) higher than that recorded in (4).
NOTE: The following operations (7) and (8) apply to 9010 and 9011 only.
(7)
Set the SENSITIVITY switch to 11.0VI.
(8)
Increase the input voltage until the counter again just commences correct
counting. Check that the input voltage is 40 dB (±3 dB) higher than that
recorded in (4).
Attenuator Type 11-0683 (9010 & 9011 only)
4.7
Solenoid Adjustment
NOTE: The following adjustments are for use in a prescribed servicing schedule, or if
Attenuator action is faulty.
(1)
Refer to the Iexploded I diagram in Fig.4.2 and unlock the armature and
backstop adjusting screws on the solenoids
RLA
and RLB (Fig.2.2 or 2.3).
Slacken each adjuster.
(2)
Switch power 'on l and energise both solenoids by setting the SENSITIVITY
switch to the l'lV" position.
9010-9013
4-4
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