Article
Active Antenna
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Short-wave listeners often are not able to, or allowed to, install a long-wire antenna or other large dimension antenna in or around the home. In such cases, the present active antenna, intended for the frequency range 3–30 MHz, may be found useful. The author used a 1-metre long rod or brass tube with a diameter of 2–6 mm.
Materials
Gerber file
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PCB
Component list
Resistors
R1 = 470k
R2 = 220k
R3 = 1k
R4 = 100
R5 = 150
R6 = 39
R7 = 1M
P1= 470 logarithmic
Capacitors
C1 = 1nF
C2,C3,C8,C9 = 100nF
C4,C10 = 47µF 25V radial
C5,C7 = 47pF
C6 = 500pF tuning capacitor
Inductors
L1,L2,L6 = 10 turns 0.7mm ECW, 4mm diameter (wind on 3.5mm drill bit)
L3 = 1 turn 0.7mm ECW, around L4
L4 = 8 turns 0.7mm ECW, 12mm diameter (wind on 10 mm drill bit)
L5 = 22 turns 0.7mm ECW, 12mm diameter (wind on 10mm drill bit)
L7,L8 = 1mH miniature choke
Semiconductors
T1 = BF247B
T2 = BF245A
T3 = 2N5109
Miscellaneous
PCB, ref. 040383-1 from The PCBShop
R1 = 470k
R2 = 220k
R3 = 1k
R4 = 100
R5 = 150
R6 = 39
R7 = 1M
P1= 470 logarithmic
Capacitors
C1 = 1nF
C2,C3,C8,C9 = 100nF
C4,C10 = 47µF 25V radial
C5,C7 = 47pF
C6 = 500pF tuning capacitor
Inductors
L1,L2,L6 = 10 turns 0.7mm ECW, 4mm diameter (wind on 3.5mm drill bit)
L3 = 1 turn 0.7mm ECW, around L4
L4 = 8 turns 0.7mm ECW, 12mm diameter (wind on 10 mm drill bit)
L5 = 22 turns 0.7mm ECW, 12mm diameter (wind on 10mm drill bit)
L7,L8 = 1mH miniature choke
Semiconductors
T1 = BF247B
T2 = BF245A
T3 = 2N5109
Miscellaneous
PCB, ref. 040383-1 from The PCBShop
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