A new method is presented for producing tunable ns duration pulse train from a fiashlamp pumped dye laser using gain saturation and frequency locking effect. This method employs two coupled cavities. A tunable seeded pulse, which is produced in a short cavity contained tuning elements, is injected into another long cavity without tuning elements. Then the pulse modulation is formed and continued relying on gain saturation. The spectrum of the output pulses is locking at the frequency of the seeded pulse relying on the frequenoy locking effect. This method gives a higher tuning efficiency. The number of the output pulses can be controlled without pulse selective arrangements, with the Rh6G in ethyl alchol the pulse trains of 3 ns duration pulses with less than 0.01 nm spectral width were obtained.