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26.

 

After all 10 range / coupling combinations are calibrated, power cycle the 
instrument. When the lock-in turns on, with the 50 Ω or shorting cap still 
installed and the frequency at 3.0 Hz (set by the Offset Cal function), verify the 
displayed “R” value is less than 1.0 mV on all settings of Input Range and 
Coupling. 

Summary of Contents for SR86 Series

Page 1: ...hich the user suspects a damaged or destroyed input JFET Symptoms of a damaged JFET can be excess noise or partial or complete signal loss The SR86x series lock in amplifiers are designed to permit th...

Page 2: ...strument 1 Turn off power to the unit and remove the AC power cord Disconnect all other cables from the SR865 To access the preamplifier the top and bottom covers must be removed from the unit 2 Remov...

Page 3: ...2 3 Remove the top cover Turn the instrument upside down carefully resting on the top Remove the 4 large black screws from the bottom cover 2 on each side 2 4 Remove the 6 small black screws from the...

Page 4: ...urn the instrument on its side so the SIGNAL section is near the top 4 Disconnect the white coax cable and the RJ style modular cable from the preamplifier enclosure Do not attempt to disconnect the r...

Page 5: ...ly back the preamp enclosure out of the instrument chassis 6 1 Pull the box back from the front panel so the BNC connectors all slide back out of the instrument Be careful to not tug on the remaining...

Page 6: ...7 Open the preamp assembly by removing the two small hex screws from the front using the 0 050 hex driver and the 6 Phillips head screws Remove the lid to the preamp assembly 8 Locate Q202 the input J...

Page 7: ...cement JFET to match the removed part Notice that two of the socket positions on Q202 are left empty it is critical that the new part be installed with this same orientation leaving the top and bottom...

Page 8: ...hould be exterior to the walls 11 2 Loosely thread the two small hex screws in the front but do not tighten 11 3 Loosely thread the remaining 6 Phillips screws again without tightening 11 4 Tighten th...

Page 9: ...13 1 Check that the BNC connectors are fully engaged and flush to the front panel partial fully 13 2 Apply pressure to keep the preamp engaged when reinstalling the two 6 hex screws Be sure to instal...

Page 10: ...screws 16 2 Loosely thread the 4 large black screws 16 3 Tighten the 6 small black screws 16 4 Tighten the 4 large black screws 17 Install a 50 terminator or a shorting cap onto the A input BNC 18 Re...

Page 11: ...Offset Cal tile to calibrate the 100 mV DC range 24 4 Press the INPUT RANGE Down Arrow button to select 30 mV input range Touch the Offset Cal tile to calibrate the 30 mV DC range 24 5 Press the INPU...

Page 12: ...calibrated power cycle the instrument When the lock in turns on with the 50 or shorting cap still installed and the frequency at 3 0 Hz set by the Offset Cal function verify the displayed R value is...

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