Subscribe to Our Youtube Channel
Related Manuals for GRAS 42AP
Summary of Contents for GRAS 42AP
- Page 1 G R A S SOUND & VIBRATION Skovlytoften 33, 2840 Holte, Denmark LI0053 www.gras.dk gras@gras.dk...
- Page 2 Before shipment, remove the batteries and wrap separately. Assure cautious han- dling during transport. Remove the battery as soon as it is discharged or if the 42AP is stored for a prolonged period of time. Leakage from the batteries may otherwise destroy the electronic components.
-
Page 3: Table Of Contents
G.R.A.S. Sound & Vibration CONTENTS General Description ..........5 Operation . - Page 4 G.R.A.S. Sound & Vibration...
-
Page 5: General Description
G.R.A.S. Sound & Vibration General Description The G.R.A.S. Pistonphone Type 42AP (Fig. 1.1) is a battery-operated, precision sound source for accurate and reliable calibration of measurement microphones, sound level meters and other sound measuring equipment. Operation When power is turned on, the coupler size will be displayed and the LED will light red. -
Page 6: Operating Frequencies
Note: When the Pistonphone is calibrated, it must be calibrated with its ½”coupler (RA0048), its 1" coupler (RA0023), and, if purchased, the two-port calibration coupler (RA0024). Factory setting True centre frequency of a 250 Hz ⅓-octave band filter 114 dB is the equivalent of 10 Pa Pistonphone Type 42AP - Page 6... -
Page 7: Theory
Since the grid and equivalent volumes can vary slightly from one type of microphone to another, the total volume of the coupler will, accordingly, also vary slightly. Pistonphone Type 42AP - Page 7... -
Page 8: Static-Pressure Corrections
The G.R.A.S. Microphone Type 40AG is equivalent to the Brüel & Kjær Type 4134 and the volume correction for these are 0 dB. As a matter of interest, the volume correction for a G.R.A.S. Type 40AU and a Brüel & Kjær Type 4180 is 0.077 dB. Pistonphone Type 42AP - Page 8... -
Page 9: Built-In Barometer
The Pistonphone has a thermometer that measures the temperature of the Pistonphone. The thermometer tracks the actual calibration temperature in the measuring chamber to within a degree. The measured temperature can be displayed both as °C and °F. Pistonphone Type 42AP - Page 9... -
Page 10: Handling And Operation
The Pistonphone can operate continuously for about 10 hours on a new set of batteries. Remove the battery as soon as it is discharged or if the 42AP is stored for a prolonged period of time. Leakage from the batteries may otherwise destroy the electronic components. -
Page 11: Calibrating Microphones
Pistonphone’s nominal sound pressure level L , the static pressure cor- rection L and the volume correction L , i.e.: The ½" coupler is individual calibrated with the pistonphone, and these must be considered as a pair Pistonphone Type 42AP - Page 11... -
Page 12: Microphones
The static pressure within the coupler volume is equalised via an air-equalisation tube located under the cap which protects the pistons and retention spring shown in Fig. 2.1. Pistonphone Type 42AP - Page 12... -
Page 13: 1" Microphones
Then insert the 1" microphone into the 1" coupler. Make sure that the microphone is all the way in. Fig. 3.6 1" and ½" couplers The 1" coupler is individual calibrated with the pistonphone, and these must be considered as a pair Pistonphone Type 42AP - Page 13... -
Page 14: Calculation Of Microphone Sensitivity
To measure the “Open Circuit Sensitivity” of the microphone (i.e. when the micro- phone’s output is not affected by the load of a preamplifier), a special preamplifier, for example the G.R.A.S. Type 26AG (which has insert voltage calibration capability), should be used. Pistonphone Type 42AP - Page 14... -
Page 15: Remote Control Via Rs-232 Interface
Note: The RS-232 connection must always be made with the Pistonphone disconnected from an external power supply. AA0050 Socket for external power supply To a COM port, e.g. COM2 Fig. 4.1 Pistonphone connection to computer Developed for Microsoft by Hilgraeve Inc. ® Pistonphone Type 42AP - Page 15... - Page 16 G.R.A.S. Sound & Vibration Fig. 4.2 Selecting the COM port in use, e.g. COM2 Fig. 4.3 Showing the correct setup for the selected COM port Pistonphone Type 42AP - Page 16...
-
Page 17: Behaviour
Returns calibration level in decibels at reference conditions for a 1″ coupler. The equivalent of <CRLF> i.e. “Carriage Return Line Feed”. However, the commands ignore the <LF>. “Carriage Return Line Feed” which moves the cursor to the start of a new line. Pistonphone Type 42AP - Page 17... -
Page 18: Setup Commands
In this example, the terminal has been setup to echo the outgoing commands. Pistonphone pow- ered up Response to the command Commands Fig. 4.4 Example of a dialogue showing commands and responses Pistonphone Type 42AP - Page 18... -
Page 19: Specifications
Four standard LR6-AA alkaline cells External power: Voltage: 6 V DC Current: 90 mA Dimensions: Length: 184 mm (7.24 in) Width: 35 mm (1.38 in) Height: 35 mm (1.38 in) Weight (with batteries): 437 g (1 lb) Pistonphone Type 42AP - Page 19... - Page 20 Two-port Coupler RA0024 shown here with the two phase-matched microphones of an intensity probe Manufactured to conform with: CE marking directive: 93/68/EEC WEEE directive: 2002/96/EC RoHS directive: 2002/95/EC For Pistonphones fitted with a 1″ microphone coupler RA0023 Pistonphone Type 42AP - Page 20...
-
Page 21: A Appendix
The curves in Fig. A.2 show corrections (C) which account for the effects of both temperature and humidity when the ambient pressure equals the reference pressure P (101.3 kPa). Fig. A.2 Corrections for temperature humidity Pistonphone Type 42AP - Page 21... - Page 22 ⋅ C ⋅ + 0.0064 dB (10) Where: = measured static ambient pressure (hPa) = reference static pressure (1013 hPa) The correction ∆L has to be added to the other correction factors in equations 5, 6, 7 and 8. Pistonphone Type 42AP - Page 22...
Need help?
Do you have a question about the 42AP and is the answer not in the manual?
Questions and answers