40 Watt Amplifier For FM Broadcast by MRF171A

This amplifier was built based on Marconi's website, A Design for a 40W broadband VHF RF Power Amplifier for FM broadcast. A few minor tweaks were made to the schematic and a few parts were changed to what I had available (mostly surface mount components). The heatsink is from an old Motorola Mostar 800 MHz radio, and has the perfect heatsink island to match the MRF171A. Also used is a Progressive Concepts external LPF7002 low pass filter because it was also on hand. Since the MOSFET uses 28 VDC, I had to homebrew a 28 Volt / 5 Amp power supply using the schematic found in the ARRL handbook.

Tune up went exactly as stated in the how-to, with the RF power output hitting 57 Watts when driven with a stock Broadcast Warehouse 1 Watt LCD PLL transmitter at 98 MHz. Liberal use of ferrite beads and feedthru capacitors are on all RF detector, fan control and SWR control circuits.

Read More Source:
http://www.geocities.com/Area51/Nebula/3736/40watt.html
Thank you.

Active FM Antenna Amplifier by C2570

My friend to need circuit FM Antenna Amplifier.

I find circuit, to see good web: http://www.uoguelph.ca/~antoon/circ/activefm.html

Content in Article : I copy to you. thank you Tony van Roon

Parts List:
R1 = 27K
R2 = 270 ohm
R3 = 1K

Tr1,Tr2 = 22pF, trimmer cap (15-40pF)
C1,C2 = 5.6pF
C3 = 0.001uF (1nF), ceramic
C4,C5 = 10pF, ceramic
C6 = 0.1uF (100nF), ceramic

Q1 = 2SC2498, 2SC2570, 2N5179, SK9139, or NTE10. NPN VHF/UHF transistor
L1 = 4 turns of 20SWG magnet wire, 5mm diameter. (so-called 3T+1)
L2 = 3 turns of 20SWG magnet wire, 5mm diameter.

With only a small handfull of parts you can built this trusty FM Amplifier.

This amplifier will pull in all distant FM stations clearly. The circuit is configured as a common-emitter tuned RF pre-amplifier wired around VHF/UHF transistor Q1.

All capacitors are ceramic and 50V is the standard but the 25V types work fine too. Trimmer capacitors Tr1 and Tr2 (22pF) are adjusted for maximum gain.
Input coil L1 consists of 4 turns of 20SWG enamelled copper wire over a 5mm diameter former. It is tapped at the first turn from the ground lead side. Coil L2 is similar to L1, but has only three turns. Pin configuration is shown in the diagram.