Model 7117C has the following two main functions: A.Model-7117C can measure the Fo value of a loudspeaker fully automatically, with no need for manual adjustment of the instrument. The correct Fo value of a loudspeaker is displayed on the DISPLAY PANELã??( 14 ) in just 1 to 1.5 seconds. It has many advantages to using a voltmeter with a needle indicator for measuring the Fo value of a loudspeaker: ( a ) Easy to read; ( b ) No visual error; ( c ) High accuracy. B. Model-7117C can be used in a production line: high speed judging if the Fo value of every loudspeaker is within the qualified range, Judging speed is as fast as in just 0.3 to 0.7 seconds, the â?? PASS / FAIL Testâ?? functions will be indicated instantly. Technical specificationï¼? A. Display: Displayed in 3 �¾digits. B. Accuracy: Fo readout error less than �± ( 1% + 1Hz ) C. Measuring Range: 4 ranges from 16Hz to 3KHz, ( a ) 16Hz - 80Hz ; ( b ) 54Hz - 270Hz. ( c ) 180Hz - 900Hz ; ( d ) 600Hz - 3KHz. D. Fo measuring voltage added on the pre-measure loudspeaker: 1V r.m.s. �± 10%( complies with EIA standard ). E. Can test the impedance of an under-testing loudspeaker: Divided into two ranges, which are (1) 3�© to 18�©; (2) 19�©to 100�©. F. Measuring Speed: ã?? Fo Readout ã??in 1 to 1.5 seconds. ã??PASS / FAIL Testã??in 0.3 to 0.7 seconds. G. Limit Setting: Both the upper & lower limits of a loudspeaker can be preset independently from 16Hz to 3KHz, and have no interference with each other. H. Limitation in usage: Model-7117C can not be used to measure the Fo value of an air suspension loudspeaker, including those loudspeakers which are air-tight frames, since their Q.o. values are too low to measure. SUNLIGHT AUDIO SWEEPER 7116C Loudspeaker Polarity Tester 139B NOISE GENERATOR 8121C GAUSS METER 138 IMPEDANCE METER 152A DIGITAL HIGH-SPEED Fo METER 7117 C.