CCWN76:80
                PETIT LOGIC SYSTEMS
                TEST SPECIFICATION FOR THE PETIT CCW FILTER by
Ray Petit
          
                Test equipment required: Oscilloscope, voltmeter,
frequency counter,
                audio amplifier/speaker, synthesized audio
                generator, l-MHz frequency standard
          
      1. Connect power, freq. std, audio amp. to filter. Ground
input of
     Diagnostics:filter. Set S2 to 10 bits/sec. With audio
amplifier on and
      connected to filter output, apply power and l-MHZ
simultaneously.

     Steps 1_~
                   A brief burst of 500-Hz tone which quickly
disappears indicates
                   normal operation. Switch S2 to 5, then 2, then
1 bit/sec. At
                   each change a tone may appear, then disappear.
A very low-level
                   tone output may run continuously. The level of
500-Hz squarewave
                   at the outputs of IC18 should not exceed 0.2 v
pk-pk. Measure
                   these signals at TP1 and TP2. Set S2 to 10
bits/sec.
             
                2. Set the synthesized audio generator to 1000.0
Hz. Set its output
                level to about 10 mV pk-pk and connect it to the
CCW filter input.
          
      Connect the scope to the filter output. Increase and
decrease
     Step 5     the level of the filter input. Above a certain
point, increasing

             the input will not increase the output level. Set
the input level
             to half the voltage that produced this limiting and
make a note
             of this level. This level will hereafter be called
the reference
             input level (RIL).
             
         3 Set the generator to 1002 0 Hz. The filter output
should now
             include a distinct popping sound. Reduce the filter
input to
             one tenth RIL. Set generator to 1000.0 Hz. Set S2 to
1 bit/sec.
             The output should be essentially the same level as
the level
             produced by RIL at 10 bits/sec. Set generator to
1000.2 Hz.
             and note popping sound once per second.
             
          . Set generator to 1000.0 Hz, RIL. Set S2 to 10
bits/sec. Note
             the filter output level with scope. Set generator to
1010.0 Hz.
             The output level should drop by at least 20 dB, to
less than one
             tenth the previous voltage. Now increase the
generator output
             to ten times RIL. The output level should not
increase noticeably
             (except during tho time you are actually changing
the input level).