SRS Labs SR550 User manual
MODEL
SR550/552
Voltage Pre-amplifier
1290-D Reamwood Avenue
Sunnyvale, CA 94089 U.S.A.
Phone: (408) 744-9040, Fax: (408) 744-9049
Email: info@thinkSRS.com • www.thinkSRS.com
Copyright © 1999, 2001
Stanford Research Systems, Inc.
All Rights Reserved
Rev. 2.6 (08/2001)
Voltage Pre-amplifier
Stanford Research Systems
manual
SR550 Preamplifier Specifications Summary
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OPERATING INSTRUCTIONS
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THE SR550 WITHOUT A LOCK-IN
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PARTS LIST
REF. SRS part# VALUE DESCRIPTION
/ 8,83 'G Capacitor, Electrolytic, 50V, 20%, Rad
/ 8&8 G Capacitor, Electrolytic, 16V, 20%, Rad
/& 8&8 G Capacitor, Electrolytic, 16V, 20%, Rad
/, 88> 'G Capacitor, Tantalum, 35V, 20%, Rad
/ 88> 'G Capacitor, Tantalum, 35V, 20%, Rad
/( 88> 'G Capacitor, Tantalum, 35V, 20%, Rad
/> 8&8 ,>G Capacitor, Electrolytic, 25V, 20%, Rad
/H 8&8 ,>G Capacitor, Electrolytic, 25V, 20%, Rad
/3 88> 'G Capacitor, Tantalum, 35V, 20%, Rad
/ 8(8 'G Cap, Stacked Metal Film 50V 5% -40/+85c
/ 8(8 'G Cap, Stacked Metal Film 50V 5% -40/+85c
9 &88&& "B9 LED, T1 Package
9 &88&& 5"BB% LED, T1 Package
I 8,8( 3:%9 Connector, D-Sub, Right Angle PC, Female
: ,8&,8,, Pot, Multi-Turn, Side Adjust
: ,88,, J Pot, Multi-Turn Trim, 3/8" Square Top Ad
:/ >8338> "8 Printed Circuit Board
K &8,8&& %(, Transistor, TO-71 Package
" ,83&8, ('J Resistor, Carbon Film, 1/4W, 5%
" ,8,>8, ' Resistor, Carbon Film, 1/4W, 5%
"& ,8,>8, ' Resistor, Carbon Film, 1/4W, 5%
", ,8>8, 'J Resistor, Carbon Film, 1/4W, 5%
" ,8>8, 'J Resistor, Carbon Film, 1/4W, 5%
"( ,8(38,H ( Resistor, Metal Film, 1/8W, 0.1%, 25ppm
"> ,8(38,H ( Resistor, Metal Film, 1/8W, 0.1%, 25ppm
"H ,8,8,> Resistor, Metal Film, 1/8W, 1%, 50PPM
"3 ,88, Resistor, Carbon Film, 1/4W, 5%
" ,88, Resistor, Carbon Film, 1/4W, 5%
" ,8(8, ,J Resistor, Carbon Film, 1/4W, 5%
" ,88, >J Resistor, Carbon Film, 1/4W, 5%
"& ,8(8, ,J Resistor, Carbon Film, 1/4W, 5%
", ,8H8, ,> Resistor, Carbon Film, 1/4W, 5%
" ,8(H8,H 3HH Resistor, Metal Film, 1/8W, 0.1%, 25ppm
"( ,8(H8,H 3HH Resistor, Metal Film, 1/8W, 0.1%, 25ppm
"> ,8H8,> & Resistor, Metal Film, 1/8W, 1%, 50PPM
"H ,8,8,> Resistor, Metal Film, 1/8W, 1%, 50PPM
"3 ,8&8, J Resistor, Carbon Film, 1/4W, 5%
" ,8&8, J Resistor, Carbon Film, 1/4W, 5%
" ,8H8, ,> Resistor, Carbon Film, 1/4W, 5%
" ,8H8, ,> Resistor, Carbon Film, 1/4W, 5%
"& ,83&8,> ,33 Resistor, Metal Film, 1/8W, 1%, 50PPM
", ,8&8, ,'&J Resistor, Carbon Film, 1/4W, 5%
" ,8>8, Resistor, Carbon Comp, 1/2W, 5%
"( ,8&(8,> Resistor, Metal Film, 1/8W, 1%, 50PPM
"> ,8&(8,> Resistor, Metal Film, 1/8W, 1%, 50PPM
"H ,8>8,H 'J Resistor, Metal Film, 1/8W, 0.1%, 25ppm
"3 ,8>8,H 'J Resistor, Metal Film, 1/8W, 0.1%, 25ppm
"& ,838,> 'J Resistor, Metal Film, 1/8W, 1%, 50PPM
"& ,8&8,> 'J Resistor, Metal Film, 1/8W, 1%, 50PPM
"& ,838, ( Resistor, Carbon Film, 1/4W, 5%
"&& ,88, >J Resistor, Carbon Film, 1/4W, 5%
A 88> 9:9- Switch, On-None-On, Toggle, Right Angle
G &8,8& >37 Transistor, TO-92 Package
G &8H8& >H7 Transistor, TO-92 Package
G& &83&8&, 7&&3 Integrated Circuit (Thru-hole Pkg)
G, &8(8&, 7-> Integrated Circuit (Thru-hole Pkg)
G &8>(8&, 95 Integrated Circuit (Thru-hole Pkg)
G( &8(8&, 7-> Integrated Circuit (Thru-hole Pkg)
G> &8&H8&, >,*/&3 Integrated Circuit (Thru-hole Pkg)
L 88 &)H? Lugs
L 8,&8 ,8,JB: Nut, Kep
L 8>38& ,8,@&)() Standoff
L 88& 8),?M, Wire #24 UL1007 Strip 1/4x1/4 Tin
L 8,83 *BB- Mylar Sheet
L 8,38 ,8,@),: Screw, Flathead Phillips
L 8HH8 "==- Hardware, Misc.
L 8&8 4%/ Connector, BNC
L 8,8> 9438943) Cable Assembly, Multiconductor
L 8>&8 %7 Connector, BNC
Z 0 7-00097-720 SR550-2 Fabricated Part
Z 0 7-00098-720 SR550-3 Fabricated Part
PC Layout
MODEL SR552
Voltage Pre-amplifier
Stanford Research Systems
manual
SR552 Preamplifier Specifications Summary
IInput Impedance 100 KΩ+ 25 pF
Inputs Single ended or differential (switch selectable)
Maximum Inputs 70 mV rms for overload
Damage threshold: 20 Vac, 50 Vdc
Noise 1.4 nV/√Hz at 1000 Hz
1.6 nV/√Hz at 100 Hz
2.5 nV/√Hz at 10 Hz
(all figures are Typical)
Common Mode Range: 1 Volt peak
Rejection: 100 dB at 100 Hz
Gain 10,20,50,100
SR510/530 Automatically set by SR510 or SR530 Lock-In depending on
sensitivity and dynamic reserve. Sensitivity ranges from 10 nV to 200
mV full scale (with expand off).
Note: Lock-in readings must be divided by 10.
DSP Lock-Ins Gain is set to 100. Divide lock-in recordings by 100 for correct
amplitude.
Gain Accuracy 2% (2 Hz to 100 kHz)
Gain Stability 200 ppm/°C
Outputs (A) single ended (600Ωimpedance)
(B) shielded ground
Maximum Output 10 Volts peak
Power Supplied by SRS Lock-In via control cable.
Mechanical Size 1.3" X 3.0" X 5.1"
Weight 1 lb.
Warranty One year parts and labor on materials and workmanship.
Noise Figure Contour
OPERATING INSTRUCTIONS
The SR552 Voltage Pre-Amplifier is designed to
be used with either the SR510/530 lock-ins as
well as the newer DSP lock-ins. The SR552
reduces the input noise and extends the full
scale sensitivity to 10 nV (without expand).
When used as a remote pre-amplifier, the
SR552 can eliminate the effects of noise pickup
on long signal cables.
Power and control are supplied to the SR552 via
the 9 pin cable which is supplied with the unit.
Attach one end of the cable to the connector on
the rear of the SR552. With the lock-in power
off, connect the other end of the cable to the
PRE-AMP connector on the rear of lock-in. Both
ends of the cable are equivalent. If a longer
cable is required, any standard 9 pin cable will
suffice since all connections are straight
through. When the lock-in power is on, the
POWER indicator on the SR552 will light.
CONNECTING THE SR552
The (A) Output of the SR552 should be
connected to the (A) Input of the lock-in. For
most applications, this single connection will be
adequate. The lock-in Input Selector should be
set to (A). For situations where there may be
noise pick-up on this cable, it is better to connect
the SR552 (B) Output (shielded pre-amp
ground) to the (B) Input of the lock-in as well.
The (A) and (B) cables should be twisted
together to prevent inductive pick-up. The lock-
in Input Selector should then be set to (A-B).
The SR552 (A) and (B) Inputs should now be
used as the lock-in voltage inputs. The input
switch selects single ended, (A), or differential,
(A-B), operation. The input impedance is 100
kΩ, 25 pF. The connector shields are isolated
from the chassis ground by 10 Ohms. These
inputs are protected to 100 Vdc but the ac input
should never exceed 10 V peak. The maximum
input before overload is 70 mV rms. The
OVERLOAD indicator will light whenever the
pre-amplifier overloads. Note that overloads
that occur after the pre-amplifier are indicated by
the lock-in's overload indicator.
USING THE SR550 WITH THE SR510/530
The SR510/530 lock-ins sense the presence of
the SR552 through the power cable and takes it
into account when setting the gain of its own
amplifiers. Thus, to obtain the correct overall
gain, the SR552 output must be connected to
the voltage inputs of the lock-in.
The overall sensitivity of the lock-in plus the pre-
amplifier is displayed as the sensitivity on the
lock-in front panel. It is necessary to divide the
displayed sensitivity by 10.
The gain of the SR552 is 10, 20, 50, or 100.
The gain is controlled by the lock-in and is set to
maximize the pre-amplifier gain while
maintaining the selected dynamic reserve. For
most sensitivities, the pre-amplifier gain will be
100. The following table summarizes the gain
allocation.
SR552 Pre-Amplifier Front Panel and Rear Panel
DYN RES FS Sensitivity SR552 Gain
LOW > 50 mV 10
20 db 50 mV 20
20 mV 50
< 20 mV 100
NORM > 5 mV 10
40 db 5 mV 20
2 mV 50
< 2 mV 100
HIGH > 500 µV10
60 db 500 µV20
200 µV50
< 200 µV 100
When the SR552 is connected, the full scale
sensitivity can extend to 10 nV (no expand).
The 10, 20, 50 nV sensitivities can be reached
using the normal lock-in controls. If the SR552
is disconnected while the sensitivity is below 100
nV, the sensitivity will revert back to 100 nV.
From the computer interface, the presence of
the SR552 can be determined using the 'H'
command. Also, gain codes 1-3 are acceptable
in the 'G' command to set sensitivities below 100
nV. Pre-amplifier overloads are not detectable
via the computer interface.
USING THE SR552 WITH SRS DSP LOCK-INS
The SR552 is not sensed by the DSP lock-ins.
The DSP lock-in does NOT compensate for the
gain of the preamp. The gain of the preamp is
set to 10. Measurements made with the preamp
need to be divided by 100.
The SR552 is AC coupled from 1 Hz to 100 kHz.
Set the lock-in input to AC coupled since the
signal must be above 1 Hz. Frequencies below 1
Hz will not be detected by the SR552.
COMMON MODE ADJUST
The common mode rejection of the SR552 is
adjusted by the small screw on the right side of
the enclosure. The CMR is set at the factory,
however, it may be necessary to re-adjust it,
particularly if there is one specific frequency
which is important. The easiest way to peak the
CMR is to use the internal oscillator of the lock-
in (or any signal generator). Apply a reference
signal to the lock-in REFERENCE INPUT.
Apply a 100 mV signal to both the (A) and (B)
inputs of the SR552. Check the SR552
connections by switching the input selector to
(A). The lock-in should read 100 mV (with the
phase adjusted on the SR510). Now switch the
SR552 to (A-B). Adjust the lock-in sensitivity to
obtain a 50% output. Adjust the CMR screw on
the SR552 to minimize the lock-in output. On
the SR510, it is necessary to check the output
when 90° of phase shift is added as well. On a
dual phase lock-in, use the R output to avoid
phase shifts.
The SR552 without a lock-in
The SR552 can be powered with an external
power supply. Power is applied through the 9
pin connector as described below.
Pin Voltage Current
1 +20 V 100 mA
2 +5 V 10 mA
6 -20 V 100 mA
7,8 Ground
All three voltages are required. Pins 7 and 8
should be tied together. All other pins should be
left open. The gain will be 100 in this
configuration. Grounding pin 3 will change the
gain to 50, and grounding pin 4 will change the
gain to 20. Grounding both pins 3 and 4 will
change the gain to 10.
PARTS LIST
REF. SRS part# VALUE DESCRIPTION
C 1 5-00040-509 1.0U Capacitor, Electrolytic, 50V, 20%, Rad
C 2 5-00030-520 2200U Capacitor, Electrolytic, 16V, 20%, Rad
C 3 5-00030-520 2200U Capacitor, Electrolytic, 16V, 20%, Rad
C 4 5-00100-517 2.2U Capacitor, Tantalum, 35V, 20%, Rad
C 5 5-00100-517 2.2U Capacitor, Tantalum, 35V, 20%, Rad
C 6 5-00100-517 2.2U Capacitor, Tantalum, 35V, 20%, Rad
C 7 5-00044-509 47U Capacitor, Electrolytic, 50V, 20%, Rad
C 8 5-00044-509 47U Capacitor, Electrolytic, 50V, 20%, Rad
C 9 5-00100-517 2.2U Capacitor, Tantalum, 35V, 20%, Rad
C 10 5-00034-526 100U Capacitor, Electrolytic, 35V, 20%, Rad
C 11 5-00034-526 100U Capacitor, Electrolytic, 35V, 20%, Rad
C 12 5-00192-542 22U MIN Cap, Mini Electrolytic, 50V, 20% Radial
C 13 5-00008-501 22P Capacitor, Ceramic Disc, 50V, 10%, SL
C 14 5-00008-501 22P Capacitor, Ceramic Disc, 50V, 10%, SL
D 1 3-00011-303 RED LED, T1 Package
D 2 3-00010-303 GREEN LED, T1 Package
J 1 1-00014-160 9 PIN D Connector, D-Sub, Right Angle PC, Female
P 1 4-00354-445 20 Pot, Multi-Turn, Side Adjust
P 2 4-00353-441 100 Pot, Multi-Turn Trim, 3/8" Square Top Ad
PC1 7-00127-701 SR552 Printed Circuit Board
Q 1 3-00231-328 MAT02-EH Transistor, TO-78 Package
R 1 4-00093-401 6.2K Resistor, Carbon Film, 1/4W, 5%
R 2 4-00047-401 2.2 Resistor, Carbon Film, 1/4W, 5%
R 3 4-00047-401 2.2 Resistor, Carbon Film, 1/4W, 5%
R 6 4-00356-407 20 Resistor, Metal Film, 1/8W, 1%, 50PPM
R 7 4-00356-407 20 Resistor, Metal Film, 1/8W, 1%, 50PPM
R 8 4-00141-407 100 Resistor, Metal Film, 1/8W, 1%, 50PPM
R 9 4-00052-401 20 Resistor, Carbon Film, 1/4W, 5%
R 10 4-00052-401 20 Resistor, Carbon Film, 1/4W, 5%
R 11 4-00061-401 240K Resistor, Carbon Film, 1/4W, 5%
R 12 4-00082-401 470K Resistor, Carbon Film, 1/4W, 5%
R 13 4-00061-401 240K Resistor, Carbon Film, 1/4W, 5%
R 14 4-00021-401 1.0K Resistor, Carbon Film, 1/4W, 5%
R 15 4-00351-407 2.32K Resistor, Metal Film, 1/8W, 1%, 50PPM
R 16 4-00351-407 2.32K Resistor, Metal Film, 1/8W, 1%, 50PPM
R 17 4-00180-407 301 Resistor, Metal Film, 1/8W, 1%, 50PPM
R 18 4-00141-407 100 Resistor, Metal Film, 1/8W, 1%, 50PPM
R 21 4-00176-407 3.01K Resistor, Metal Film, 1/8W, 1%, 50PPM
R 23 4-00193-407 499 Resistor, Metal Film, 1/8W, 1%, 50PPM
R 24 4-00093-401 6.2K Resistor, Carbon Film, 1/4W, 5%
R 25 4-00107-402 10 Resistor, Carbon Comp, 1/2W, 5%
R 26 4-00142-407 100K Resistor, Metal Film, 1/8W, 1%, 50PPM
R 27 4-00142-407 100K Resistor, Metal Film, 1/8W, 1%, 50PPM
R 28 4-00204-407 750 Resistor, Metal Film, 1/8W, 1%, 50PPM
R 29 4-00204-407 750 Resistor, Metal Film, 1/8W, 1%, 50PPM
R 30 4-00158-407 2.00K Resistor, Metal Film, 1/8W, 1%, 50PPM
R 31 4-00178-407 3.83K Resistor, Metal Film, 1/8W, 1%, 50PPM
R 32 4-00081-401 470 Resistor, Carbon Film, 1/4W, 5%
R 33 4-00082-401 470K Resistor, Carbon Film, 1/4W, 5%
RU7A 4-00032-401 100K Resistor, Carbon Film, 1/4W, 5%
RU7B 4-00032-401 100K Resistor, Carbon Film, 1/4W, 5%
SW1 2-00025-217 SPDT Switch, On-None-On, Toggle, Right Angle
U 1 3-00124-325 79L15 Transistor, TO-92 Package
U 2 3-00118-325 78L15 Transistor, TO-92 Package
U 3 3-00193-340 LM339 Integrated Circuit (Thru-hole Pkg)
U 4 8-00085-860 SR513 ASSY SRS sub assemblies
U 5 3-00076-340 DG211 Integrated Circuit (Thru-hole Pkg)
U 7 3-00038-340 74HC139 Integrated Circuit (Thru-hole Pkg)
Z 0 0-00025-005 3/8" Lugs
Z 0 0-00043-011 4-40 KEP Nut, Kep
Z 0 0-00079-031 4-40X3/16 M/F Standoff
Z 0 0-00122-053 2-1/4" #24 Wire #24 UL1007 Strip 1/4x1/4 Tin
Z 0 0-00140-009 SHEET Mylar Sheet
Z 0 0-00149-020 4-40X1/4PF Screw, Flathead Phillips
Z 0 0-00188-000 SR552FOOT Hardware, Misc.
Z 0 1-00003-120 BNC Connector, BNC
Z 0 1-00041-170 DB9-DB9/MM Cable Assembly, Multiconductor
Z 0 1-00073-120 INSL Connector, BNC
Z 0 7-00098-720 SR552-3 Fabricated Part
Z 0 7-00128-720 SR552-2 Fabricated Part
PC Layout
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