G.R.A.S. 40HF Instruction Manual
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G.R.A.S. 40HF Instruction Manual

Single-channel low-noise measuring system
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Instruction Manual
Single-channel Low-noise Measuring
System consisting of:
1-inch Low-noise Level Microphone
System Type 40HF and
Power Module Type 12HF
G.R.A.S.
Sound & Vibration
Skovlytoften 33, 2840 Holte, Denmark
Type 40HF
Type 12HF
Tel. +45 45 66 40 46
Fax +45 45 66 40 47

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Summary of Contents for G.R.A.S. 40HF

  • Page 1 Instruction Manual Single-channel Low-noise Measuring System consisting of: 1-inch Low-noise Level Microphone System Type 40HF and Power Module Type 12HF Type 40HF Type 12HF G.R.A.S. Sound & Vibration Skovlytoften 33, 2840 Holte, Denmark Tel. +45 45 66 40 46 Fax +45 45 66 40 47...
  • Page 2 Single-channel Low-noise Measuring System consisting of: 1-inch Low-noise Level Microphone System Type 40HF Power Module Type 12HF Revision 19 10 2015...

  • Page 3: Table Of Contents

    Specifications ..........12 1-inch Low-noise Microphone System Type 40HF ......12 Single-channel Power module Type 12HF (separate order) .

  • Page 4: Introduction And Description

    / Free Field: on the front panel of the power module (see Fig. 2.1). Fig. 1.4 shows the responses of the two compensation filters as well as the free-field response for 0 ° incidence. Note: free-field corrections are added to the lowest curve. Fig. 1.5 shows the what these free-field corrections are for various angles of incidence. Fig. 1.6 shows, for a complete low-noise measuring system, a typical noise floor in ⅓-octave bands for both the linear and A-weighted cases. Single-channel Low-noise Measuring System consisting of: Type 40HF and Type 12HF - Page 4...
  • Page 5 AL0006 Type 12HF) Fig. 1.3 A Single-channel Low-noise Measuring System as described in this document, shown here with Tripod and Tripod Adapter (both available from G.R.A.S.) Single-channel Low-noise Measuring System consisting of: Type 40HF and Type 12HF - Page 5...
  • Page 6 G.R.A.S. Sound & Vibration Fig. 1.4 Typical frequency response curves of Type 40HF Fig. 1.5  Free-field corrections for various angles of incidence on the 1-inch Microphone Type 40EH. Single-channel Low-noise Measuring System consisting of: Type 40HF and Type 12HF - Page 6...
  • Page 7 G.R.A.S. Sound & Vibration Fig. 1.6  Typical noise floor of Type 40HF for system and microphone. Shown in ⅓-octave bands for  both the linear and A-weighted cases Single-channel Low-noise Measuring System consisting of: Type 40HF and Type 12HF - Page 7...

  • Page 8: Power Module Type 12Hf

    Power Supply is 1.1 V RMS, the microphone is being sub- jected to 94 dB re. 20 μPa. The actual sensitivity is quoted on the individual calibration chart supplied with each Type 40HF. Important! The Single-channel Power Module Type 12HF (available from G.R.A.S.) is a dedicated module.

  • Page 9: Rear Panel

    Fuse 315 mA fast blow Input for external Power Supply 6 V - 20 VDC Locking screw for base plate Fig. 2.3 Rear panel of the Power Module Type 12HF Single-channel Low-noise Measuring System consisting of: Type 40HF and Type 12HF - Page 9...

  • Page 10: Battery Pack

    Pull out the battery pack See Fig. 2.4. The battery pack consist of a battery holder and 4 x LR14 (C) standard alkaline cells. When replacing the batteries, replace all of them making sure that the polarity is as indicated on the battery holder. Fig. 2.4  Showing the battery pack of the Power Module Type 12HF Single-channel Low-noise Measuring System consisting of: Type 40HF and Type 12HF - Page 10...

  • Page 11: Operation

    Unscrew and remove the normal coupler of the Pistonphone. Screw the Coupler RA0090 to the Pistonphone, see Fig. 3.1. Mount the microphone of the Type 40HF in the Coupler as shown in Fig. 3.2 and switch the Pistonphone on. Adjust the analyser to indicate 94 dB* re. 20 μPa.

  • Page 12: Measurements

    At this point you can make your measurements but keep an eye on the overload warning LEDs to avoid overloading the system and invalidating the measurements. Single-channel Low-noise Measuring System consisting of: Type 40HF and Type 12HF - Page 12...

  • Page 13: Specifications

    7-pin LEMO EGA 1B connector Outputs channel: BNC socket Output impedance: 30 Ω Polarisation voltage: 200 V Power supply: internal: 6 V from 4 x LR14 (C) standard alkaline cells external: 6 V - 20 V DC via included Mains Adapter AB0010 Dimensions: height: 132.6 mm (5¼ in) width: 34.6 mm (1.3 in) depth: 196.0 mm (7.7 in) Single-channel Low-noise Measuring System consisting of: Type 40HF and Type 12HF - Page 13...

  • Page 14: Common

    RA0093 3 m Ext. cable: AA0046 10 m Ext. cable: AA0047 30 m Ext. cable: AA0048 Manufactured to conform with: CE marking directive: 93/68/EEC WEEE directive: 2002/96/EC RoHS directive: 2002/95/EC Single-channel Low-noise Measuring System consisting of: Type 40HF and Type 12HF - Page 14...

This manual is also suitable for:

12hf

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