|
"The circuit of fig. 5 can be used as an rf or if stage. Due to the extremely high gate impedance, feedback can be troublesome when high-Q tuned circuits are used. An if amplifier usually depends on the first filter for its selectivity so you can
afford to swamp the input with a 2200 or 2700 resistor. This will make a completely stable system.
The receiver in fig. 2 (not shown here) uses two of these stages. The first is swamped with the filter terminating resistor, the second stage with 2200 ohms - the two stages become very docile. As an rf amplifier the circuit will require careful shielding of the input and output circuits. By reducing the value of C5 and adding a "gimmick" capacitor or small adjustable capacitance between the junction of C5, R4 and L2 to gate 1 you can include neutralization with the same layout. Agc or mvc can be included as shown. Limit this voltage to + or - 4 volts on gate 2. Maximum gain requires +4 volts from gate 2 to the source. Fig. 5 includes another form of output circuit. The slug-tuned coil can be a TV IF coil rewound for your frequency. For this service you must provide space to drill a 5/16-inch hole to mount the coil. If you don't need a low impedance output, capacitor C9 can be connected across the coil and C10 can be eliminated." |
Return to Amateur Radio Receivers ||
LED Mosfet Receiver
|| Send E-Mail