75 meter qrp ssb transceiver  

Added on
Feb 6, 2014
In general, the transceiver switches the 4-element 1500 ohm xtal BPF ends between the inputs and outputs of the two SA602s to reverse the signal flow for R/T operation. Since no IF amplifier is used in the design, 20 dB of additional receiver gain is produced by the 2N2222 receiver RF amplifier, while automatic gain control (AGC) is produced by the peak DC swing of the
75 meter qrp ssb transceiver - schematic

LM386 output passed through a rectifier and filtered by a capacitor and fed to the gate of a BS170 enhancement mode FET acting as a variable resistor across the input of the LM386. 50 ohm antenna feeds half-pi band pass filter (BPF, element Q=5) which feeds receive-transmit (R/T) switch which feeds 2N2222 receive RF amplifier which feeds 1st SA602 which feeds R/T switch which feeds 4-element 1500 ohm xtal BPF which feeds R/T switch which feeds 2nd SA602 which feeds LM386 which feeds 1) diode which feeds capacitor which feeds gate of BS170 which produces audio automatic gain control (AGC) and 2) speaker attenuator which feeds speaker.

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