BRUEL & KJAER 2225 - Use with Other Instruments; DC Level Recording Setup

4. USE WITH OTHER INSTRUMENTS
4.1. DC LEVEL RECORDING
The Portable Level Recorder Type 2306 is well suited for use with the Types 2225 and
2226, being operated from internal batteries. It is connected directly to the "DC OUT-
PUT" of the meter via a cable (B & K order Number AO 0173) with a standard BNC plug
at the recorder and a standard 2,5 mm mini jackplug at the meter. When this is inserted
it overrides the automatic "switch-off" feature and the "Max. hold" mode of the 2226 al-
lowing the meter to run continuously in all modes of operation. In "60s Leq" the accu-
mulated value is continously recorded, the final value being the Leq for one minute, and
the meter is reset to start a further "60s Leq" measurement.
In "Peak" (2225 Only), the maximum peak is held for 0,3 s and then reset, unless a
higher peak occurs during that time, causing an immediate reset.
The procedure is as follows:
1. Calibrate the meter (including checking the batteries) as in Section 3.4.
2. Ensure that the POLARITY REVERSER of the 2306 is in the + position and that no
leads are connected to SIGNAL INPUT.
3. Set RECORDING MODE slider-switch on the 2306 to "DC Lin" and select the re-
quired writing and paper speed. A 250 mm/s writing speed is recommended as this
is fast enough to faithfully reproduce the levels even in the "peak" mode of the
2225.
4. Using DC LIN POSITION adjust the pen position to lie exactly on the lower line of
the paper. See Fig.4.1 .
Fig. 4.
1. Calibrating the Type 2306 using the Type 4230 calibrator
5. Connect the DC OUTPUT of the Type 2225 or 2226 to the SIGNAL INPUT of the
2306 using cable AO 0173.
6. Place the Sound Level Calibrator Type 4230 over the microphone, switch on both
calibrator and sound level meter and set FUNCTION SELECTOR to "Fast".
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