Active FM Antenna Booster


Active FM Antenna Booster

 

Active FM Antenna Booster

 


This is a simple active antenna booster. This amplifier will pull in all distant FM stations clearly. The circuits is configured as a common-emmitter tuned RF preamplifier wired around VHF/UHF transistor Q1. Input coil L1 consists of four turns of 20SWG enamelled copper wire (slightly space wound) over 5mm diameter former. It is tapped at the first turn from ground lead side. Coil L2 is similar to L1, but has only three turns. Pin configuration of transistor 2SC2570 is shown in the fm antenna booster schematic. Adjust input/output trimmers (VC1/VC2) for maximum gain.

Active FM Amplifier



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 = 0.01 (10nF), 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 enameled 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.


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