PSK31 Receiver Project: Testing

By | 14/03/2014

rf amplifier Q1Testing of the PSK31 Receiver has shown that the audio output section is satisfactory. White noise is clearly heard on headphones inserted in the output jack socket. The level is easily controlled by preset resistor R8, the gain control for IC2 (LM386) [1] . With an antenna connected to the board however the PSK31 tones were not heard. Further investigation showed that rf amplifer transistor Q1 was not the 2n3819 JFET specified. The relevant section of the board and schematic are shown below.schematic rf amplifier

The incorrect device seems to be marked as a BC256B. This is a pnp Bipolar transistor and not the JFET required. It has been removed. The board will be re-tested when the 2n3819 is fitted. An update will follow.

[1] Complete Circuit Diagram