Receiver for Jupiter
|RF Amp||Narrow Band Pass Filter||Mixer||Low Pass Filter||Audio Preamp||Audio Power Amp|
The audio preamplifier used in this receiver is low noise audio preamplifier LA 3161 which is designed for amplification of week signals from tape head. It has closed loop voltage gain of 35dB. And equivalent i/p noise voltage of 1.2microV. This makes it suitable for week signal amplification. The amplifier operates at 9V. The amplifier along with the external components is available on a single board at nominal cost of 35 Rs. So I am using the ready made board of LA3161 used for tape head amplification in my receiver as a low noise preamplifier. The voltage gain of this circuit is 35dB. LA3161 has two i/p channals , so any one can be used with other left unconnected. The circuit diagram of the amplifier is given in figure.
One can also use the audio section design given in Jove receiver manual. In that NTE824 is used as preamplifier. NTE 824 has an equivalent LM 387; so LM 387 can also be used without alteration in circuitry.