This new FM Power amplifier is equiped with the famous Mosfet transistor: the BLF245.

Depending on the output power level your FM synthesizer is able to provide, you can use or not the 2N4427 driver stage.

We've chosen the synthesizer n°1 (described on this Website) to drive this amplifier unit.
By the way,we will use the 2N4427 driver stage to boost properly the BLF245
.
All the impedance networks (Input & Output) have been determined by using the softwares: Mimp.EXE & Genesys.

Due to the new 20W FM transmitter developped on this website, we have corrected and modified the amplifier schematic
in order to improve most of the RF values.
The main modifications are located in the driver stage and in the output matching network of the BLF245.

Impedance matching network file(PDF)

A 9 elements low pass filter ensures that we meet at least a 60 dB rejection from the carrier.(RF Simulation with RFSIM99

Low pass filter measurements file(PDF)

Frequencies	Output Power Level	Gain	VDD	Current	Efficiency
88 MHz	24 W	26.8 dB	24V	1.8 A	56 %
98 MHz	27 W	27.3 dB	24V	1.77 A	64 %
108 MHz	24 W	26.8 dB	24V	1.55 A	65 %

Gain and Ros measurements file(PDF)

The FM amplifier has a 27 dB gain (with driver stage) and provides 25W with a 60% efficiency.
(No tune is needed to cover all the FM Band).

Amplifier schematic PDF File