Wide band high frequency amplifier

This is Wide band high frequency amplifier circuit, a Wide frequency band between 75-150 MHz, Using transistors, a PNP amplifier. To enhance the signal strength. Before the receiver of the phone. Or FM radio or amateur radio.

If high-frequency signals, in particular, its VHF. The booster circuit is one, serves to amplify the signal strength only.

Operation of the circuit

High-frequency range VHF, inductive antenna, to the emitter pin of the transistor Q1. so circuit held, in conjunction with the bass, a nice low output impedance. You can use a special access code 50 ohms, the antenna on the circuit at all.

The Signal at the Q1 will be expanded to increase. And sent to a tuner or receiver to the receiver.

Wide band high frequency amplifierFigure 1 The wideband high frequency amplifier circuit.

The L1 coil wire enamel No. 24 SWG, thousands of rounds of 10, inside diameter 3 mm. And the coil L2 wire number. Thousands of 13 turns, diameter 5 mm. Stent both as a non-core, or an air core.

The power supply is +5 V, this circuit while current is 2.5 mA. If the components to use. Should be based on the antenna. And design of high frequency printed circuit boards as well.

How to assemble circuits
The assembling circuit onto the universal PCB board as Figure 2 May have problems, the interference inserted come in, If assembly circuit to actually use. Should have a basic antenna and PCB design in high frequency reasonable.

The components list
Resistors size ¼ W +5%
R1, R2__________18K
R4_____________220 ohm
C1, C3__________0.0056uF 50V
C2_____________56pF 50V
C4_____________5.6pF 50V
Q1___________BF324___PNP Transistors
L1___is 10 turns of 24 SWG enamel coated magnet wire wound with a inside diameter of about 3mm. no core.
L2____is 13 turns of 24 SWG enamel coated magnet wire wound with an inside diameter of about 5 mm. no core.
The Universal PCB board

Figure 2 the component layouts of this circuit

Keep reading: ‘Simple Active Antenna in SW/MW/FM bands’ »

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The BF324 transistor has a transition frequency of 450MHz, which is not much higher than common transistors like the 2N3906 (pnp) or 2N3904 (npn). This is one reason why the common-base configuration is used here. A npn transistor like the BF199 might be a better bet, but the polarity of the supply would need to be reversed. As both supply lines are at ground potential as far as signal voltages are concerned, the output could still be referenced to the negative rail.

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