Receiver for Jupiter
|RF Amp||Narrow Band Pass Filter||Mixer||Low Pass Filter||Audio Preamp||Audio Power Amp|
The RF amplifier used in this project is the single stage RF amplifier using N-channel JFET (J310). The JFET is used in common-gate configuration. The common-gate amplifier is often used in high-frequency applications, as its bandwidth is much greater than that of common source amplifier. Another reason for its use is that the circuit configurations offers low i/p impedance, which is convenient for matching to transmission line.
The i/p tank circuit formed by L1,C2,C3 is used to tune the RF
amp. to 20.1MHz. The Pi-attenuator at o/p matches the o/p impedance to 50
ohms. The resistors R1 and R2 are the biasing resistors for JFET. L3 and L2
acts as a Radio Frequency Choke to avoid RF signal to go in to DC power line.
The RF amplifier used after the Narrow band pass filter is same as shown in
diagram. So receiver contain two stages of same RF amplifier one before and
other after the narrow band pass filter. The 0.47microH
air core inductor is made from #24 gauge insulated copper wire wound on 3mm
former giving 22 turns in 1inch.
Specifications of RF Amplifier: -
|3. Noise Figure||3.195dB|
|4. Noise Temperature||315.17 Kelvin|
|5. Minimum Discernible signal (BW=3.3KHz)||-133.34dBm|
|6. 1dB compression point||-12dBm|
|9. Center Frequency||20.1MHz|