The LHCD System is commissioned on the SST- 1 tokamak for the current drive. It has a capability to generate power of 2 MW CW at 3.7 GHz and deliver the power to the tokamak via a grill antenna through a phased array of waveguides. The system relies on 4 Klystrons (TH-2103D) each generating 500 kW CW power. The klystrons act as an amplifier providing a gain of 40 dB with a bandwidth of 10 MHz and amplify the input power provided by a solid state driver. The klystron requires a supply of 65 kV and 20A for its operation and has to be extensively conditioned before it can be operated even for obtaining lower power levels. As such there is a requirement of a compact, low cost source which can give an output of 50W to 1kW at 3.7 GHz with a very narrow bandwidth. This can be achieved by the use of solid state devices (transistors). However the power handling of a solid state device is limited (1 kW). Higher power levels can be achieved by using many such solid state devices in parallel and then combining each of their output power. An effort to build such a modular device through which we can obtain variable output power (50W to 1kW CW) at 3.7 GHz has been initiated. This paper describes the design of oscillator for such a system. The oscillator is based on bipolar junction transistor BFR360F. Linear and non-linear analysis has been performed on the design to ascertain its performance. The oscillator delivered a power of 20 mW at 3.7 GHz.