• on Audio/Video/Photography
  • Published in issue 2/2005 on page 0
About the article

VHF FM Antenna Booster

New horizons in 3-metre band DXing

VHF FM Antenna Booster

Together with a good directional antenna this high performance two-stage antenna amplifier for the VHF FM broadcast band will enable you to capture far removed (DX) stations. Alternatively, it will drastically improve reception of FM signals you’ve come to accept as marginal and noisy in your area. FM broadcast transmitters are normally meant to have a useful range of 30-100 km. Fine, but if you are in a fringe area, all you may get is a very weak signal, possibly even blotted out by a powerful station around the corner.

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Gerber file

CAM/CAD data for the PCB referred to in this article is available as a Gerber file. Elektor Members can exclusively download these files for free as part of their Membership. Gerber files allow a PCB to be produced on an appropriate device available locally, or through an online PCB manufacturing service. Elektor recommends its business partner Eurocircuits as the company of choice for its own prototypes and volume production in selected cases.

R1 = 10kOhm
R2 = 150kOhm
R3 = 1MOhm
R4 = 220Ohm
R5 = 100kOhm
R6 = 3Ohm3
R7 = 1kOhm
R8 = 1kOhm2*
P1 = 47kOhm preset H
P2 = 10kOhm linear potentiometer
C1, C6 = 22pF ceramic
C2, C5, C14 = 22pF trimmer
C3, C7, C17, C18 = 1nF ceramic
C4, C9, C13, C15 = 100nF ceramic
C8, C10 = 10nF ceramic
C11, C16 = 100µF 25V radial
C12 = 3pF9 ceramic
C19 = 12pF ceramic
D1,D3 = 1N4007
D2 = LED
T1,T2 = BF965 or BF966S
FB1,FB2,FB3 = 5 turns 0.15 mm (38SWG) enamelled copper wire on ferrite bead
L1 = 7 turns 0.9 mm dia. (20SWG) enamelled copper wire; internal dia. 5mm; length 10mm; tap at 5 turns from ground
L2,L3 = 7 turns 0.9 mm dia. (20SWG), internal dia. 5mm; closewound
L4 = 30 turns 0.15mm dia (38SWG) enamelled copper wire on a 1MOhm 0.5W resistor
K1-K4 = F socket, PCB mount
S1 = on/off switch, 1 contact
PCB, ref. 040145-1
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