Anfatec AFT400B User manual

AFT400B
Differential Preamplifier
Anfatec Instruments AG
Melanchthonstr. 28
08606 Oelsnitz /V.
Germany
Tel.: [phone]
Fax.: [phone]
http://www.anfatec.de
email: [e-mail]
Manual AFT400B – Rev. 1.02 dated 30/09/20 Page 1 (10)

•Table of Contents
• 1 WARRANTY.......................................................................................................................3
• 2 Specification of the AFT400B..............................................................................................4
• 2.1 General Parameters....................................................................................................4
• 2.2 Signal Input...............................................................................................................4
• 2.3 Filter and Gain............................................................................................................4
• 2.4 Noise & CMRR Specification.........................................................................................5
• 2.5 Standard Part List.......................................................................................................5
• 3 Safety Requirements..........................................................................................................6
• 4 Installation........................................................................................................................8
• 4.1 Get Started................................................................................................................8
• 4.2 Connections to the AFT400B.......................................................................................8
• 4.3 Switches & Knobs.......................................................................................................8
• 5 Schematic & Functional Description.....................................................................................9
• 6 Revision History.................................................................................................................9
Copyright 2002-2020 Anfatec Instruments AG. All rights reserved. Anfatec is a trademark of
Anfatec Instruments AG. Other product and brand names may be trademarks or registered
trademarks of their respective owners.
Anfatec Instruments AG assumes no responsibility for any damage or loss resulting from use of
this manual.
Anfatec Instruments AG assumes no responsibility for any damage or loss resulting from use of
the software. Anfatec Instruments AG assumes no responsibility for any damage or loss by
deletion of data as a result of malfunction, dead battery, or repairs. Be sure to make backup
copies of all important data on other media to protect against data loss.
Important: Please read the Anfatec Licence Agreement contained in this handbook before using
the accompanying software programs. Using any part of the software indicates that you accept
the terms of Anfatec Software Licence Agreement.
Manual AFT400B – Rev. 1.02 dated 30/09/20 Page 2 (10)

1
1 WARRANTY WARRANTY
Anfatec warrants that this product will be free from defects in materials and workmanship for a
period of two years from the date of shipment. If any such product proves defective during this
warranty period, Anfatec, will either repair the defective product without charge for parts and
labour or will provide a replacement in exchange for the defective product.
In order to obtain service under this warranty, the end user must notify Anfatec of the defect in
writing before the expiration of the warranty period. The customer is responsible for packaging
and shipping the defective product to Anfatec's head quarter with shipping charges prepaid.
Anfatec pays the return shipping costs for customers inside EU. For customers outside EU, the
customer is responsible for paying all duties, taxes, and any other charges for products returned
to any other locations.
This warranty shall not apply to any defect, failure or damage caused by improper use or improper
or inadequate maintenance and care. Anfatec is not obligated to furnish service under this
warranty to repair damage resulting from improper use or connection to incompatible equipment
or to service a product that has been modified or integrated with other products when the effect
of such modification or integration increases the time or difficulty of servicing the product.
Manual AFT400B – Rev. 1.02 dated 30/09/20 Page 3 (10)

2
2 SPEC F CAT ON OF THE SPEC F CAT ON OF THE AFT400B AFT400B
2.1 GENERAL PARAMETERS
Gain x1, x10, x100 or x1000
Filter Bandwidth (-3 dB) 100 Hz, 1 kHz, 10 kHz, 100 kHz or 1 MHz
Switched Manual Output Offset 10-turn Potentiometer
-10 V .. 10 V referred to output
Input Modes In, -In and ( In ‒ -In)
Input Coupling DC or AC with f-3dB = 1.2 Hz
Input referred Noise (Gain x1000) < 1 nVrms/√(Hz) for f>100 Hz
Positive and negative Overload LEDs
Remote Control Interface (optional) Optical Fibre
Resistor coded Gain Output (optional)
Power Supply Requirement DC 12 V, > 400 mA
Power Supply Input C14 connector, 100 V ... 240 V / 47..63 Hz
Weight 450 g
Housing Size 20 cm (L) x 10.5 cm (W) x 5 cm (H)
2.2 S GNAL NPUT
Connector Isolated BNC
Input GND to Output GND 100 Ohm
Common Mode Input Range (DC coupled) -10 V ... 10 V
Input Resistance (DC coupled) 1 M
Input Capacitance Gain x1 & x10 for f<100 kHz 39 pF -30/ 0%
Damage Threshold
DC coupled, Gain x1, x10 & x100 ± 12 V
DC coupled, Gain x1000 ± 10 V
AC coupled, all Gains 10 V peak, for sine signal: 7 Vrms
Voltage Rating of Input Capacitor 250 V
For safety reasons never operate above 40 V
Internal thermal Fuse for Gains x1, x10 and x100 63 mA
No Fuse ! for Gain x1000
Swift AC Coupling Feature DC to AC switching results in fast signal
equalizing to zero
2.3 F LTER AND GA N
Filter 100 Hz, 1 kHz, 10 kHz, 100 kHz 2nd Order
f-3db (for 100 mV at output) ± 10%
Full Bandwidth in Gains x1 & x10 1 MHz
Full Bandwidth in Gains x100 & x1000 Limited by Circuit Design to 600 kHz
Amplitude Accuracy
@10 Hz all Gains, all Filter < 1 %
Harmonic Distortion @ 0.2 VRMS, 1 kHz < 10 µV (3th harmonic)
Manual AFT400B – Rev. 1.02 dated 30/09/20 Page 4 (10)

Gain1 Full BW, 3 VRMS, 1 kHz
Output Offset (Manual Offset off, Full BW) Referred to input
Gain x1 < 2 mV
Gain x10 < 0.2 mV
Gain x100 < 0.1 mV
Gain x1000 < 50 µV
2.4 NO SE & CMRR SPEC F CAT ON
Input Referred Noise (0 W @ input) @ 1 kHz
Gain x1 < 150 nV/√(Hz)
Gain x10 < 20 nV/√(Hz)
Gain x100 < 10 nV/√(Hz)
Gain x1000 < 1 nV/√(Hz)
CMRR 1 kHz / 1 Vrms on Input typ.
Gain x1 > 75 dB
Gain x10 > 90 dB
Gain x100 > 100 dB
Gain x1000 > 125 dB
CMRR 100 kHz / 1 Vrms on Input typ.
Gain x1 > 70 dB
Gain x10 > 80 dB
Gain x100 > 85 dB
Gain x1000 > 90 dB
2.5 STANDARD PART L ST
AFT400B 1
Power Supply 1
Manual 1
Low-Noise BNC cable, 2 m long 1
Manual AFT400B – Rev. 1.02 dated 30/09/20 Page 5 (10)

3
3 SAFETY REQU REMENTS SAFETY REQU REMENTS
Please read the following safety precautions before starting up the preamplifier to avoid injury or
damage to devices. In order to avoid any risks, please use the preamplifier merely as stated in this
manual.
Use proper supply voltages
In order to avoid fire hazards and electric shocks as well as damage to the device, only supply
voltages as specified in this manual.
Ground properly
The device is supposed to be grounded through inputs and output. Always ensure proper
grounding before switching on the device to avoid electric shock.
Use input connections properly
The inputs of the device is shielded and the shield is connected to ground via 100 Ohm. Never
apply a voltage to the shield; it may cause damage to the device.
Use proper input voltages
In order to avoid damage to the pre-amplifier do not apply voltages higher than specified.
Applying voltages higher than specified will damage the device and void the warranty.
Never supply the two inputs "+ N" and - N" with voltages
larger than specified!
MPORTANT NOTE:
The inputs do NOT survive voltages higher than specified. The
AFT400B is operated without fuse in gain x1000.
Observe all device ratings
Be aware of any ratings the pre-amplifier shows. Read the instructions in this manual before
making any connections. Damage to the device as well as electric shocks can be caused.
Use with supplied housing
Never operate the pre-amplifier without the supplied housing. Do not touch any wires or
components of the circuit.
Use overload protection
In order to avoid electric shock and damage to the device, ensure proper overload protection e.g.
by a lightning stroke.
Do not operate a possibly broken pre-amplifier
In case the pre-amplifier could be damaged, do not operate it any more. Please contact service
personnel for maintenance.
Do not operate in an explosive atmosphere
In order to avoid injury or damages to the pre-amplifier, do not operate the device in an explosive
atmosphere.
Manual AFT400B – Rev. 1.02 dated 30/09/20 Page 6 (10)

Do not use in humid environment
Do not use the pre-amplifier in humid environment or in liquids in order to avoid electric shock and
damage to the device.
Maintain the device clean and dry
In order to avoid the influence of dust and humidity of the atmosphere, keep the device clean and
dry.
Electrostatic prevention
In order to avoid electrostatic damage, ensure grounding of both the exterior and interior
conductors before connecting to the pre-amplifier.
Ensure proper ventilation
In order to avoid damage to the pre-amplifier ensure proper ventilation.
Handle safely
Please handle safely during transportation to avoid damage.
Manual AFT400B – Rev. 1.02 dated 30/09/20 Page 7 (10)

4
4 NSTALLAT ON NSTALLAT ON
4.1 GET STARTED
☑Connect OUT to the oscilloscope or measurement tool
☑Always start with a low gain (e.g. x1), never gain x1000
☑Switch IN and or -IN to AC, GND or DC (depends on application)
☑Connect the 12 V power supply to “Power”
☑Connect IN to your source
☑Use Gain x1000 only, if there is no need for a fuse
4.2 CONNECT ONS TO THE AFT400B
Power Requires 12 V dc, >400 mA
Inner pin is positive.
+ N non-inverted input
- N inverted input
OUT output of the amplifier
4.3 SW TCHES & KNOBS
AC/GND/DC ... switches the input coupling
type for the two signals IN and -IN
independently. For single input
configuration, set this switch behind "-IN" to
"GND"
Gain … switches the total amplification
between x1, x10, x100 and x1000.
MPORTANT NOTE: the range "x1000"
requires special care.
Bandwidth ... adds low pass filters behind
the amplification stage.
Offset ... for large amplifications (x100 or
x1000), it might be required to DC shift the
OUT signal.
Manual AFT400B – Rev. 1.02 dated 30/09/20 Page 8 (10)
Figure 1: Top View onto the AFT400B

5
5 SCHEMAT C & FUNCT ONAL DESCR PT ON SCHEMAT C & FUNCT ONAL DESCR PT ON
The idea of this pre-amplifier is to enable oscilloscopes with low resolution to measure smaller
voltages by amplification of the original signal. Within the output range of the pre-amplifier the
original signal can be amplified in steps of 10 up to x1000 times. Additionally, a low-pass is
implemented, where several corner frequencies can be selected. If two similar signals need to be
compared, the pre-amplifier allows subtraction of the two signals at equal pre-amplification
factors.
As shown in Fig. 2, the coupling of each input IN and -IN can be selected between AC, GND and
DC coupling. A fuse protects the input of the 1st operational amplifier against too high currents. In
case of a x1000 amplification, this fuse is bridged.
For single ended signals, the not used input needs to be switched to GND. An overload after the
first amplifier stage is detected for each input separately and displayed by a red LED. In order to
adjust for too large signal differences between IN and -IN in the higher amplifications (x100 and
x1000), an offset can be added manually with a 10-turn potentiometer onto the pre-amplified -IN
signal prior to the differential amplifier. The selectable bandwidth filters are located directly at the
output.
6
6 REV S ON REV S ON H STORY H STORY
2020, the specifications on page 4ff. have been loosened in order to achieve a more robust long
term compliance of the same.
Manual AFT400B – Rev. 1.02 dated 30/09/20 Page 9 (10)
Figure 2: Schematic diagram of the AFT400B low noise differential amplifier.

•Alphabetical ndex
•Connectors................................................................................................................8
•Input........................................................................................................................4
•Installation................................................................................................................8
•Revision History.........................................................................................................9
•Safety Requirements..................................................................................................6
•Schematic Diagram....................................................................................................9
•Signal Input...............................................................................................................4
•Specification of the....................................................................................................4
•WARRANTY...............................................................................................................3
•................................................................................................................................3
Manual AFT400B – Rev. 1.02 dated 30/09/20 Page 10 (10)