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12 June 2009

15dB UHF Antenna Preamp Circuit

This is an UHF band TV antenna preamp circuit with 15dB gain and build by a transistor. It is formed based on BF180 UHF Transistor. This circuit is a simple circuit. This is a figure of the circuit.

The principle operation of the circuit is two stages. The first stage is an band pass filter constructed by the C1, CV1, L1, L4, C7 and C3, the second stage is a base-common voltage amplifier with low input impedance to match. Build the L1 ~ L4 as air core coil to obtain high Q-Factor. You can find out about air core coil construction and calculation here. After assembling, pack it into a proper metallic box and connect the ground of the circuit to the box to reduce noise effect.