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SECTION I1
OPERATING INSTRUCTIONS
2-1 INSTALLATION
No special operating precautions are necessary for installing the
540A except when it is to be operated near vibrating machinery.
Even though the 540A is not prone to microphonics, its extreme
resolution makes very small frequency changes readily observable,
and the effects of vibration may become apparent. If vibrating
machines create a disturbance in frequency measurement, the 540A
should be shock-mounted or placed on soft shock-absorbing mate-
rial.
2-2 POWER LINE VOLTAGE AND FREQUENCY
The 540A can be operated from either 115-volt or 230-volty 50 to
1000-cycle power lines. As shipped from the factory the 540A is
wired for operation on 115-volts. If it is to be operated on 230-
volts, the power -transformer primary windings must be connected
in series instead of in parallel as shown in the schematic diagram,
and the 1.25 amp slow blow fuse should be replaced with a 0.6
amp slow blow fuse.,
Jf the 540A is to be operated at a line frequency higher than 120
cycles the PHASE control for the self-contained oscilloscope will
not be effective. It is desirable in this case to adjust the value of
one capacitor in the PHASE control circuit, as described in para-
graph 3-7, so that the PHASE control will be effective at the higher
line frequency in use.
The three-conductor power cord for the 540A is terminated by a
polarized, three-contact plug recommended by the National Elec -
trical Manufacturers? Association for protection of operating
personnel. The third contact is an offset, round prong added to a
standard two-blade a-c connector which grounds the instrument
chassis when used with a matching receptacle. To use this
connector in a standard, two-contact a-c receptacle, the
appropriate adapter must be provided by the operator, or the
round prong can be removed from the connector.
2-3 FREQUENCY MEASUREMENT, GENERAL
This section gives step-by-step operating instructions for measur-
ing the frequency of the three most common types of r-f signals:
continuous -wave, frequency-modulated and pulsed signals. Each
procedure is accompanied by illustrations of an instrument set-up
and oscillograms showing typical beat-frequency representations.
2-1 |
ACEC
