Spectral performance for general-purpose test
Overview
The Agilent Technologies 8657A and 8657B signal generators are designed to test AM, FM, and pulsed receivers
as well as components. With their exceptional analog
modulation, good spectral purity, and superb output
level performance, these signal generators are ideal for
R&D, manufacturing, and support.
In-channel performance
Measurement confidence
The 8657A and B signal generators provide the spectral
purity and modulation versatility needed for RF testing
of communication and navigation equipment.
Low residual FM ensures wide hum and noise test margins
Hum and noise testing requires a signal generator to
have low residual FM to ensure no measurement error.
The residual FM of the 8657A and B provides the test
margins you need for the most demanding hum and
noise tests.
Output level range and accuracy for sensitivity testing
With a dynamic range from +13 to –143.5 dBm, the
8657A and B allow sensitivity measurements to be made
on even the most sensitive receivers. The 8657A and B
couple this with a level accuracy of ±1 dB (typically
0.5 dB) to –127 dBm across the full temperature range of
0 to 55 degrees C, to give you accurate and repeatable
measurements every time.
Low RF leakage eliminates measurement interference
Sensitivity measurements can often be masked by RF
leakage (radiated emissions). With the 8657A and B, RF
leakage is reduced to a level that assures virtually no
measurement interference.
DCFM faithfully reproduces digital signals
For radios with digital squelching, the 8657A and B have
extremely stable dc-coupled FM (dcFM). The dc coupling
of low-rate tones or digital data eliminates droop, and
the exceptional stability and center-frequency accuracy
when in dcFM mode eliminates the need to retune the
signal generator after dcFM is selected.
Pulse modulation with the 8657B
High-performance pulse modulation (available on the
8657B) will give you confidence in your radar or pulsed
carrier measurements. This includes rise/fall times of
<35 ns, rates from dc to 30 MHz, and better than 70 dB
on/off ratios (fc<1030 MHz).
Agilent 8657A/8657B
Signal Generators
Profile
2
Out-of-channel measurements with the 8657A/B
Low single-sideband phase noise for adjacent channel selectivity
testing
A receiver’s ability to reject unwanted signals is measured using out-of-channel tests. With its good spectral
purity, the 8657A and B make it easy to perform
demanding tests such as adjacent channel selectivity
measurements.
Adjacent channel selectivity measures a receiver’s ability
to pick out a desired signal while rejecting a strong signal one channel away. To measure adjacent channel
selectivity the out-of-channel signal generator must have
low single-sideband (SSB) phase noise and nonharmonic
spurious content at channel spacings, otherwise the inchannel signal is masked. The exceptional phase noise
performance of the 8657A and B provides a cost-effective
solution for many out-of-channel tests.
General purpose and component tests
Output power to drive high-level inputs
For applications requiring high output power, the 8657A
and B can overrange beyond the +13 dBm specified output level to >+16 dBm for most frequencies.
DCFM for VCO simulation
State-of-the-art dcFM and wide FM bandwidth make the
8657A and B ideal sources for many VCO simulation
applications. For example, the 8657A or B can be used to
replace a receiver’s VCO during design.
Phase adjust to characterize phase-sensitive devices
The 8657A and B give you the ability to adjust the phase
of the output signal in one-degree increments with
respect to a source that is locked to the same reference
timebase. This feature makes it easy to characterize
phase-detector or phase-interferometer receivers during
design or manufacturing.
Manual tests
100 nonvolatile store/recall registers save set-up time
The 8657A and B offer as a standard feature the ability
to store 100 complete instrument states. This feature
decreases set-up time when performing repetitive tests
and reduces operator errors.
Register sequencing provides semi-automation
Stepping through the store/recall registers is easy with
the front-panel sequence keys or the rear-panel remotesequence connector. These features allow the user to
sequence through the storage registers in any order.
Automated tests
Reliable output attenuators
With production lines requiring ever-faster throughput,
test equipment must be more reliable than ever. Output
level cycling requires electromechanical relays to switch
in and out of different attenuators to produce varying
output levels. The 8657A and B enhance system up-time
by using a very reliable attenuator technology. The
8657A is especially dependable with its electronic attenuator design. Instead of using mechanical relays for
switching the attenuators, the 8657A uses solid-state
components for setting output levels. The patented
design uses PIN-diode switching elements with 3 million
hours mean time between failure rate. This exceptional
reliability is backed with a 5-year warranty against
attenuator failure.
Ordering information
Please contact your Agilent Technologies Sales and
Service Office for more information or visit our website
at www.agilent.com/find/tmdir
Option Description
001 High-stability timebase
002 Rear-panel connections
003 Pulse modulation ( 8657B only)
1BN Mil std 45662A calibration certification
1BP Mil std 45622A calibration with test data
907 Front handle kit
908 Rack flange kit
909 Rack flange kit w/ front handle
910 Adds operation/calibration manual and two service manuals
915 Adds service manual
W30 3-year return repair service
W32 3-year return calibration service
W34 3-year standards compliant calibration service
W50 5-year return repair service
W52 5-year return calibration service
W54 5-year standards compliant calibration service
3
Technical specifications
Specifications describe the instruments warranted per-
formance and apply after a 30-minute warm-up. All
specifications are valid over the signal generator’s entire
operating/environment range unless otherwise noted.
Supplemental characteristics (indicated by italic type) are
intended to provide information useful in estimating
instrument capability in your application by describing
typical, but not warranted, performance.
Note: The upper frequency range of the 8657A is 1.04 GHz.
Specifications above 1.04 GHz apply only to the 8657B.
Frequency
Range
8657A 100 kHz to 1.04 GHz
8657B 100 kHz to 2.6 GHz
Underrange To 10 kHz with uncalibrated output and
modulation.
Resolution
8657A 10 Hz
8657B 1 Hz
Accuracy and stability Same as timebase
Switching speed
1
<35 ms.2(30 ms typical at 25 °C)
Phase offset Output signal phase is adjustable in
1-degree nominal increments.
Internal reference oscillator
Std. (typ.) High-stability Option 001
Aging rate ±2 ppm/yr 8657A, 1.5 x 10-8parts/day after 10 days
1.0 x 10-9parts/day after 180 days
8657B, 1.0 x 10-9parts/day after 45 days
Temperature
(0 to 55 °C) ±10 ppm 7 x 10
-9
Line voltage 2 x 10-9(+5%, –10%)
Frequency 50 MHz 10 MHz
Timebase reference Available at a level of >0.15 V
rms
into
output (rear panel) 50 Ω (output of 10, 5, or 1 MHz is selec-
table via internal jumper). If external ref-
erence is used, output will be the same
frequency.
External reference input Accepts any 10, 5, or 1 MHz ±0.002%)
(rear panel) Frequency standard at a level
>0.15 Vrms into 50 Ω
Output
Range (dBm)
8657A +13 dBm to –143.5 dBm into 50 Ω,
+10 dBm to –143.5 dBm for frequencies
from 100 kHz to 1 MHz
8657B +13 dBm to –143.5 dBm into 50 Ω,
+10 dBm to –143.5 dBm with pulse
modulation installed at fc<1.03 GHz
Resolution 0.1 dB
Absolute level accuracy
3
8657A <±1.5 dB (>+7 dBm)
<±1.0 dB (+7 to –127 dBm)
<±1.5 dB (<–127 dBm)
8657B <±1.5 dB (>+3.5 dBm)
<±1.0 dB (+3.5 to –127 dBm)
<±1.5 dB (<–127 dBm)
Level flatness
100 kHz to 2.06 GHz ±0.5 dB, output level setting of 0 dBm
Reverse power protection
to maximum output frequency) 50 watts (from a 50 Ω source)
Maximum DC voltage 8657A, 50 V
8657B, 25 V
SWR
8657A (fc(400 kHz) <1.5 for levels <–3.5 dBm
<2.0 for levels ≤ +13 dBm
8657B <1.5 for levels ≤ –6.5 dBm
<2.0 for levels ≤ +13 dBm
Output impedance 50 Ω nominal
1. To be within 100 Hz of carrier frequency.
2. Add 5 ms when switching to fc>1.03 GHz for the 8657B.
3. Absolute level accuracy includes allowances for detector linearity, temperature,
flatness, attenuator accuracy and measurement uncertainty.
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