BRUEL & KJAER 2305 - Page 39

160 mm/sec. (large figures) with 50 mm paper.
315 mm/sec. (small figures) with 100 mm paper .
6. Set PAPER DRIVE to "Stop" and "Forward".
7. Ascertain that the SINGLE CHART· CO NT . RECORD pushbutton is in
its released (upp er) position .
8.
Set POWER to " On" .
9. Set MOTOR to "On".
10. Allow a few minutes to warm-up.
11. Press the 100 mV REF. pushbutt on and adjust the deflection of the
Writing Stylus by means of the INPUT POTENTIOMETER until it is
at the 20 dB line on the recording paper .
The Recorder is now calibrated so that a voltage applied to the "Input"
will be recorded in dB re o 10 mV (O - line on the recordin g paper amplitude
scale corresponds to 10 mV) .
n. Adjustment to the Signal.
1. Lift the Pen / Sapphire by the MECHANICAL LIFTING CAM A (Fig.
3.
1) .
2. Apply
the signal to be recorded to the INPUT terminal.
3. RECTIFIER RESPONSE is set to "RMS", "Average" or "Peak" as
desired for the me asurement .
4. LOWER LIMITING FREQUENCY a nd WRITING SPEED are set to
positions, whichev er are required for the recording. See also Fig . 2.2
on page 24.
5.
INPUT ATTENUATOR is positioned so that a suitable deflection on
the recording paper is achieved.
NOTE: Do not touch the INPUT POTENTIOMETER, otherwise the
cali
bra tion will be lost.
III.
Recording.
38
1. Pull the knob marked PAPER SPEED upwards and turn to the desired
position. In some cases the gear wheels may not engage properly (the
' PAPER SPEED will not go hom e wh en lowered) because of the relative
positions of the teeth. It is then recommended to start the paper drive
for a minute period till engagement takes place, or to move Finger
wh eel Z to and fro.
2.
Two types of recording can be made:
(a) Single chart recording (automatic stop of paper drive after a
length of 250 mm paper has been run).
(b) Continuous re cording over any length of paper.
(a) Single Chart Recording:
1. Set the SYNCHRONIZING GEAR LEVER X in its outer
position . Make s'Ure that the lever is pull ed completely to
th e out po s ition by moving the grooved finger wheel Z
to and fro at the same time as pulling . (The actual paper