We observed short duration, narrow band Type IIIb radio bursts that occur just before the onset of a normal Type III burst. These observations were made with a multichannel radiometer with a center frequency of 25 MHz, time constant of 10 milliseconds and frequency resolution of 100 KHz. The average half power duration of a typical element of a Type III burst was determined. It was found to be very similar to the time profile of a normal Type III burst, i.e., sharp rise and exponential type decay. The duration of the exciter, tE, and the decay time constant, τ, determined from the average time profile were 0.88 and 0.31 seconds, respectively. The corresponding quantities for the associated Type III bursts are 6.0 and 2.1 seconds, respectively. It is interesting to note that the ratios are the same, and equal to 0.98. We found that there is no difference between the time profile of a Type III burst associated with a Type IIIb burst and that of an isolated Type III burst. We also found that the two quantities ‘tE’ and ‘ τ ’ are positively correlated in the case of isolated Type III bursts. The linear correlation coefficient is 0.70. This correlation seems to break down in the case of Type III bursts associated with Type IIIb bursts. We looked for a relation between durations of the elements of the Type IIIb bursts and that of the associated Type III bursts, and found that the two quantities are positively correlated. Lastly, we would like to point out that the elements of Type IIIb bursts observed by us are more intense than the associated Type III burst.