SR844 – 200 MHz lock-in amplifier

Technical Specifications

Signal Channel
Voltage input: Single-ended BNC
Input impedance: 50 ? or 1 M? + 30 pF
Damage threshold: ?5 V (DC + AC)
Bandwidth: 25 kHz to 200 MHz
Sensitivity:
<1 MHz 100 nVrms to 1 Vrms full scale
<50 MHz 1 ?Vrms to 1 Vrms full scale
<200 MHz 10 ?Vrms to 1 Vrms full scale
Gain accuracy:
<50 MHz ? 0.25 dB
<200 MHz ? 0.50 dB
Gain stability: 0.2 %/?C
Coherent pickup: Low noise reserve, sensitivity <30 mV
f < 10 MHz <100 nV (typ.)
f < 50 MHz <2.5 ?V (typ.)
f < 200 MHz <25 ?V (typ.)
Input noise (50 ?): 2 nV/?Hz (typ.), 8 nV/?Hz (max.)
Input noise (1 M?): 5 nV/?Hz (typ.), 8 nV/?Hz (max.)
Dynamic reserve: up to 80 dB

Reference Channel
External reference input: 25 kHz to 200 MHz
Impedance: 50 ? or 10 k? + 40 pF
Level: 0.7 Vpp pulse or 0 dBm sine
Pulse width: >2 ns at any frequency
Threshold setting: Automatic, midpoint of waveform
Acquisition time: <10 s (auto-ranging, any frequency)
<1 s (within same octave)
Internal reference: 25 kHz to 200 MHz
Frequency resolution: 3 digits
Frequency accuracy: ?0.1 in the 3rd digit
Harmonic detection: 2F (50 kHz to 200 MHz)
Reference outputs: Phase locked to Int. or Ext. reference
Front panel ref output: 25 kHz to 200 MHz square wave, 1.0 Vpp nominal into 50 ?
Rear panel TTL output: 25 kHz to 1.5 MHz, 0 to +5 V nominal, ?3 V into 50 ?
Phase resolution: 0.02?
Absolute phase error:
<50 MHz <2.5?
<100 MHz <5.0?
<200 MHz <10.0?
Rel. phase error, orthog: . <2.5?
Phase noise (external): 0.005? rms at 100 MHz, 100 ms time constant
Phase drift:
<10 MHz <0.1?/?C
<100 MHz <0.25?/?C
<200 MHz <0.5?/?C

Demodulator
Zero stability: Digital displays have no zero-drift. Analog outputs have <5 ppm/?C drift for all dynamic reserve settings.
Time constants: 100 ?s to 30 ks with 6, 12, 18 or 24 dB/octave rolloff
?No Filter? mode: 10 to 20 ?s update rate (X and Y)
Harmonic rejection:
Odd harmonics: -9.5 dBc @3 ? ref, -14 dBc @5 ? ref, etc. (20log 1/n where n = 3, 5, 7, 9…)
Even harmonics: <-40 dBc
Sub-harmonics: <-40 dBc
Spurious responses: -10 dBc @ ref ? 2 ? IF
-23 dBc @ ref ? 4 ?IF
<-30 dBc otherwise

Displays
Channel 1
Type: 4?-digit LED with 40-segment bar graph
Quantities: X, R[V or dBm], X-noise, Aux In 1
Channel 2
Type: 4?-digit LED with 40-segment bar graph
Quantities: Y, ?, Y-noise[V or dBm], Aux In 2
Expand: ?10 or ?100 for Ch1 and Ch2
Ratio: X and Y ratioed with respect to Aux In 1 or Aux In 2 before filtering and computation of R. The ratio input is normalized to 1 V and has a dynamic range greater than 100.

Reference
Type: 4?-digit LED
Quantities: Reference Frequency, Phase, Offsets, Aux Out, IF Frequency, Elapsed Time
Channel 1 and Channel 2 Outputs
Voltage range: ?10 V full scale proportional to X, Y or CH1, CH2 displayed quantity
Update Rate:
X, Y 48 to 96 kHz
R, ?, Aux inputs 12 to 24 kHz
X-noise, Y-noise 512 Hz
Auxiliary Inputs and Outputs
Inputs: 2
Type: Differential, 1 M?
Range: ?10 V
Resolution: 0.33 mV
Bandwidth: 3 kHz
Outputs: 2
Range: ?10 V
Resolution: 1 mV
Data Buffers: Two 16,000 point buffers. Data is recorded at rates up to 512 Hz and is read using the computer interfaces.

General
Interfaces: IEEE-488.2 and RS-232 interfaces are standard. All instrument functions can be controlled and read through the interfaces.
Power: 70 W, 100/120/220/240 VAC, 50/60 Hz
Dimensions: 17″” ? 5.25″” ? 19.5″” (WHL)
Weight: 23 lbs.
Warranty: One year parts and labor on defects in materials and workmanship

 

Others

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