uc3844 flyback converter startup problem

[electros6]

Hi guys,
         I designed a flyback converter using uc3844. when I power up the circuit , the voltage at the Vcc pin swings between the threshold ie approximately between 12 and 16V like a sawtooth waveform. I increase the startup current by reducing the startup resister but result in same. Can somebody figure out the problem
  attached the schematics herewith
       
   

[bktemp]

Your feedback winding does not produce enough voltage for the uc3844 to keep running. So it stops until the startup resistor recharges the capacitor.

[T3sl4co1l]

Are you actually running it from 48V, and using the winding schedule specified for the transformer?

[electros6]

No, I actually used my own designed transformer for 48V . not the one specified in the datasheet