7116C provides pure sine wave with very low total harmonic distortion. (approx. 0.1% THD ).  The total harmonic distortion of 7116C consists of 2nd Harmonic  component only and nearly without higher order harmonic components.  So,  7116C  is very  suitable  to test the sound quality ( spurious noise inspection ) of all kinds of loudspeaker, headphone, receivers,  piezo,  speakers  system…etc. 
The  frequency produced by 7116C is more  stable  than  the  ordinary  beat  frequency oscillator produced.  and  the sine  wave  provided  by 7116C  is  purer  than  the ordinary function generator.  Therefore,  7116C has both advantages of low distortion and high stability.  do  not use the  ordinary  function  generator  to  test  the  spurious  noise  ( rattle and  buzz ) of loudspeaker, loudspeaker, receiver,  etc.…  Because  user  will  easily  neglect the  prohibited  spurious  noise  caused  originally  from the high order  distortion  component of the function generator. 
 Specification 
1. Frequency  Range: Cover  20Hz  to  20KHz  in  one  range,  ( usually  under  15Hz and  higher  than  21KHz ). 2. Frequency  Counter:  4  digits  display,  resolution  1Hz,  accuracy    ±1Hz. 3. Signal: Sine  Wave,  THD. < 0.15%  ( 1KHz,  10V ),  THD. 0.1%  typical. 4. Power  Output: 7116C ( 20W ) 0- 12.6V 8 OHMS  load.    ( At  rated  line 0- 9.0V 4 OHMS  load. 
   voltage ) 7116C ( 60W ) 0- 22.0V 8 OHMS  load. 
 0 - 15.5V 4 OHMS load. 7116C ( 100W ) 0- 28.3V 8 OHMS load. 
 0 - 20.0V 4 OHMS load.    Continuously  adjustable  with  short  circuit  protection. 
5. Voltage  Meter: 3 3/4  Digits,  autorange   ( Two  Ranges ). Low  Range: 0.000V-3.300V ( Approx. )  Resolution  0.001V High  Range: 3.30V-38.00V ( Approx. )       Resolution  0.01V Accurancy:     ± 0.6% of reading ±2dgts. 
6. Output  Protection  Circuit:       Triple-protection,  The  amplifier  won't  be  burnt  out  even  if  the  output  terminal is  continuously  shorted  all  day  long.  The  output  terminal  will  become  an  open circuit  when  the  load  is  shorted,  And  will  have  power  output  again  automatically when  the  shorted  condition  was  vanished.  7. Sweeping  Mode:  Logarithmic  Sweep. 8. Sweeping  Width:  Maximum  ratio  is  1:1000,  20Hz  to  20KHz  in  one  sweep. 9. Sweep  Time:  0.3∼40  SEC.,  Continuously  adjustable. 10. Power  Consumption:  7116C ( 20W )  45VA Max.  7116C ( 60W ) 100VA Max.  7116C ( 100W ) 160VA Max. 11. Min. Loading impedance : must be > 3.2  12. Dimension:  37 ( L )  × 28 ( W ) × 13 ( H )  Cm. 13. Weight: 7116C ( 20W ) 6.0 KGS. Approx. 7116C ( 60W ) 8.0 KGS. Approx. 7116C ( 100W ) 10.0 KGS. Approx.  
1. Automatic  Sweep  Generator : Depress  Auto / Manu  (8)  pushbutton,  Then  7116C  will  sweep  forth  and  back  between the  frequencies  set  by  start  adjustment  knobs  and  stop  knob.
2. Manual  Sweep  Generator : Depress  start  (3)  or  stop  (4)  pushbutton,  adjust  Start / Stop  coarse  knob.
3. A  Constant  Frequency  Generator : Depress  start  (3)  or  stop  (4)  pushbutton,  And  adjust  start  Coarse / Fine  knob  (5) / (6) or  stop  knob  (7)  to  the  frequency  desired.
 Measuring The Lowest Resonant Frequency Fo Of A Loudspeaker 
The  lowest  resonant  frequency  of  a  midrange  or  a  tweeter  is  a  very  important parameter  when  designing  the  speaker system.  And  the  lowest  resonant  frequency of  a  woofer  would  affect  the  regeneration  of  low  frequency  greatly.  Therefore,  It's necessary  to  measure  the  Fo  value  of  each kinds  of  loudspeaker. And  7116C  can measure  the  Fo  value  manually. 
1. Connect  the  loudspeaker  to  the output  terminal  of  7116C. 2. depress  the  Fo  pushbutton  (2). 3. Adjust  the  output  voltage  to  approximately  0.5V. 4. Adjust the  start  Coarse / Fine  knob,  To  start  at  20Hz  up  to  a  higher  frequency slowly.  ( Especially  slowly  for  the  woofer )  The  voltage  value  will  increase  as  the frequency  increasing.  A  maximum  voltage  should  be  reached  at  a  certain  frequency, And  the  voltage  value will  fall  down  when  the  frequency  goes  higher  again.  Please turn  the  start  Coarse / Fine  knob  back  to  the frequency  at  the  highest  voltage,  And the  frequency is  the lowest  resonant  frequency  of  the  loudspeaker  at  that  voltage.
5. In  EIA  standard,  It  is  recommended  to  test  the  Fo  value  with  1.0V ± 10%  voltage across  the  terminals  of  the  loudspeaker.  So  user  should  adjust  the  voltage  volume to  1.0V  after  the  Fo  value  was  found.  Then  repeat  steps  1.  to  4,  To  make  sure that  the  lowest  resonant  frequency  found  is  exactly  at  the  highest  voltage  of  1.0V