1W FM Booster based 2N4427

This is the circuit diagram of linear FM Booster / RF amplifier based 2N4427 Philips transistor. The RF Amplifier is for boosting small fm transmitters and bugs. It use two Philips 2N4427 and its power is about 1Watt. At the output you can drive any linear with BGY133 or BLY87 and so on. Its power supply has to give 500mA current at 12 Volts. More voltage can boost the distance but the transistors will be burned much earlier than usual.! In any case do not exceed the 15Volts. The Amp offers 15 dB in the area of 80Mhz to 110 Mhz. L4, L5, and L6 are 5mm diameter air coils, 8 turns, with wire 1mm wire diameter. This is an easy project, but will give you great results.

5W / 150MHz RF Amplifier Circuit

This is a 5W -150MHz RF amplifier circuit. It applies the MRF123 TMOSFET. The MRF123 is a very high gain FET which potentially unstable at both VHF and UHF frequencies, so the 68 Ohm input loading resistor has been used to enhance the stability. This RF amplifier has a gain of 14 dB and a drain effeciency of 55%.

UHF-TV Preamplifier circuit

This is a low cost, antenna-mounted, this UHF TV pre-amplifier circuit can add more than 25db of gain. The first stage of the pre-amplifier is biased from optimum gain. L1, L2 strip line equivalent with Lambda/8 of PC board. The circuit uses BFQ85 as active commponent to amplify the UHF signal, the BFR90 can be used as component replacement for BFQ85.