The FM transmitter using a varactor diode way radio, plus a Class C amplifier, RF output power of up to 300 mW more open to more than one kilometer distance communications. Select the components of this fm transmitter: Q1 with ≥ 100 mA, Ft ≥ 300 MHz, β ≥ 100 tubes available 3 DG82, 3DG122, 3DG130, 2G711; Q2 with 2SC2538, 2SC1970, etc..
It must be noted in the fm transmitter assembly that RF Baffles circle L8, L9, L10; C13, C14, C17, C18, C19, and so can not be omitted, otherwise it would cause unnecessary self-excited oscillation. L1, L5 need to tap extraction, data such as icons, not otherwise due to impedance matching, the output power of less than maximum. Such as a battery-powered, Q3 (Darlington tube), C15, R6 can be omitted.
Debugging steps :
1. In the output termination of testing circuit to regulate the C7, C9, C12 to the largest multimeter readings,
2. Remove test circuit connected to one meter in length pole antenna to pull to fine-tune C12 simple reading of the largest field will be completed debugging.