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Model 654A
Section I
SECTION
GENERAL INFORMATION
1-1_
DESCRIPTlON_
1-2
.
The Hewlett-Packard Model 654A Test Oscillator is an
ideal general purpose
signal source
whenever a flat balanced
or
unbalanced test signal is required
.
Balanced outputs of
135 ohms, 150 ohms and
600
ohms have many uses in the
communications industry. Automatic leveling, together
with the expanded meter, make the 654A ideally suited to
voltmeter calibration
or
to test frequency response
of
components during
manufacture.
The instrument is shown
in Figure I-I and the specifications
are
listed in Table I-I.
General information relating to the instrument is listed in
Table 1-2. The information in Table 1-2 should not be
considered specifications.
1-3. The Model 654A is
a stable,
low distortion
sine-wave
signal
source
with a flat frequency response of
+/-0.5%
over
the frequency range of 10Hz to 10 MHz. The attenuators
allow the signal to be
adjusted
in
I
dB and 10 dB
steps
from +10 dBm to
-89
dBm, and the front panel
AMPLITUDE control allows a continuous
adjustment
in
level of +/-1 dB from the
settings shown
on the OUfPUT
LEVEL
attenuators.
The flat
frequency
response is
achieved by automatic leveling circuits within the 654A.
1-4.
Five output impedances are available, selected by a
front panel push-button control: these are 50 and 75 ohms
unbalanced and 135, 150 and 600 ohms balanced. Balance
is greater than 50 dB up to I MHz and greater than 40 dB
up to 5
MHz.
1-5. The meter scale is expanded to indicate 0 dBm at
center scale, with a total range of +/-1 dBm. The metering
circuit monitors the signal level before the attenuators
so
that the meter indication is independent
of
the attenuator
settings; the meter indicates the signal level
set
by the front
panel AMPLITUDE control. The output signal level into
the load is the algebraic sum of the meter indication and
the OUTPUT LEVEL attenuator settings.
1-6. An additional feature is the COUNTER OUTPUT rear
panel
BNC connector. This allows the Model 654A
frequency to be continuously monitored by an electronic
counter without interrupting measurements or affecting
terminal balance
.
1-7.
SUPPLIED ACCESSORIES.
Rack mount kit: -hp- Part No. 5060-0775.
1-8.
RECOMMENDED ACCESSORIES.
-hp- II 048C
50
ohm
Feedthrough Termination
-hp- II 094A
75 ohm Feedthrough Termination
-hp- 11095A
600 ohm Feedthrough Tennination
-hp-11l43A
Balanced BNC to Alligator clip
cable
1-9.
INSTRUMENT AND MANUAL IDENTIFICATION.
1-10. Hewlett-Packard uses a two-section serial number.
The first section (prefix) identifies
a
series of instruments.
The last section (suffix) identifies a particular instrument
within the series. If a letter is included with the serial
number, it identifies the country in which the instrument
was manufactured. If the serial prefix of
your
instrument
differs from the one on the title page of this manual, a
change sheet will be supplied to make this manual
compatible with newer instruments or the backdating
information in Appendix C will adapt this manual to earlier
instruments. All correspondence with Hewlett-Packard
should include the complete serial number.
1-1
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