Maintenance; Introduction; Cleaning The Air Filter; Test Equipment - HP 492A Operating And Service Manual

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Mcx:lel 492A/494A
SECTION V
MAINTENANCE
Section V
Paragraphs 5-1 to 5-6
5-1. INTRODUCTION.
5-2. This section provides maintenance and service
information for Mcx:lels 492A and 494A Traveling Wave
Tube Amplifiers.
The section includes replacement
procedures for tubes, recommended test equipment,
adjustment procedures, and troubleshooting.
This
section also includes performance checks which veri-
fy
proper instrument operation.
5-3. CLEANING THE AIR FILTER.
5-4. Inspect the air filter regularly, and clean it
before it becomes dirty enough to restrict air flow.
a. Remove filter from instrument rear, and wash
it in warm water and detergent.
b. Dry filter thoroughly and coat it with filter ad-
hesive.
We recommend Filter Coat No.3 from Re-
search Prcx:lucts Company, Inc. This adhesive comes
in "Handi-Koter" sprayer cans and is available from
most heating supply stores or from your authorized
Hewlett-Packard sales representative.
5-5. TEST EQUIPMENT.
5-6. Test equipment recommended for use in main-
taining and checking performance of the Mcx:le1s 492A
and 494A is listed in table 5-1.
Equipment having
similar characteristics can be substituted for the
equipment listed.
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Table 5-1. Recommended Test Equipment
Instrument Type
Required Characteristics
Use
Mcx:lel
AC Voltmeter
Voltage Range: 1.0 mv to 1 volt
Power supply ripple
~
Mcx:lel 4000
Voltage Accuracy: 2%
Spurious mcx:lulation check
Input Impedance: 10 megohoms
DC Voltmeter/
Voltage Range: to 1000 volts
Power supply
~
Mcx:lel 4108
Ohmmeter
Voltage Accuracy: 3%
measurements
Imput Impedance: 100 megohms
Crystal Detector
Frequency Range: to 12.4 gc
Spurious mcx:lu1ation check
~
Mcx:lel 420A
Sensitivity: approximately 0.1 V/mw
Power Meter
Power Range: up to 10 mw
Gain check
~
Model 430C
Scale must read in dbm and milliwatts
Power check
Noise figure check
DC Voltage
Division ratio:
100: 1 or 3: 1
Power supply
~
Mcx:lel 459A
Divider
Input Impedance: 12,000 megohms
measurements
Maximum Voltage: 2000 volts
Thermistor Mount
Power Range: to 10 mw
Gain check
~
Mcx:lel 4778
Frequency Range: to 10 gc
Power check
Noise figure check
Signal Generator
Frequency Range: 4 to 12.4 gc
Power source for
~
Mcx:lels 6188
Output Amplitude: at least 1 mw
performance checks
620A,626A
Waveguide Coax
SWR less than 1.25
With all checks at 10 gc
~
Mcx:lel X281A
Adapter
and above
Waveguide
Power Range: to 10 mw
Gain check
~
Mcx:lel X4878
Thermistor Mount
Frequency Range: to 12.4 gc
Power check
Attenuator
10 db power attenuation
Power check
Weinschel 210-10
00144-2
5-1

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