SR810/830/850 LINE AND 2X LINE NOTCH FILTER ADJUSTMENT
Refer to schematic 850-A2 in the manual. The pots mentioned below are easily found on
the back / top edge of the analog plug-in board in the shielded section of the lock-in.
1) If the unit is set to 50 Hz line operation and it is to be reset for 60 Hz operation, two
jumpers must be installed in the positions provided on the board at locations JP221
and JP201, behind pots P221 and P201 respectively. If chan ging from 60 H z to 50 Hz,
the jumpers must be removed.
2) To tune the notch filters for 60 Hz, set the internal source to 60 Hz and set amplitude
to 1 Volt. To tune for 50 Hz, set the internal source to 50 Hz. Connect the source
output to the input of the SR830. Set the display to read R and Phase.
3) Adjust the Dept Adj. pot P222 so the reading of R is greater than 20 mV
(approximately 23 mV is a good target number).
4) Adjust the Freq. Adj. pot P221 so that the phase is as close to 180 degrees or 0
degrees as possible.
5) Adjust Depth Adj. pot P222 for minimum reading of R (should be less than 1
millivolt, and preferably close to 100 microvolts).
6) Set the internal sou r ce to 120 Hz (or 100 Hz if the line frequency will be 50 Hz).
Repeat steps 2, 3,4 using the 2x D epth Adj. pot P202 and 2x Freq. A dj. pot P201.
3/24/98
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