Page last updated: 19/05/2013
All transistor BC547 SSB HF Transceiver
Detailed here within is an all transistor SSB HF single band transceiver originally designed for the 80m band by John VK3AJG I have made some very minor alterations purely to suite the components I had at hand, and have included a PCB layout.
Transceiver description single conversion super heterodyne, with a 6MHz intermediate frequency, four pole crystal ladder SSB filter. Receiver audio output of 250mW, and transmit RF output of 600mW
Starting in receive mode, and the RF front end comprising T101,T102,C101,C102, & C103 forming a double tuned band pass filter impedance matched to both the antenna and RF amplifier Q101. Diodes D101 & D102 limit the RF input to a maximum of 600mV, whilst D103 forms a diode switch, grounding the input to Q101 during transmit.
The mixer / IF subsection used for both transmit and receive, comprising active balanced mixer Q102, Q103, & Q104 followed by a four pole crystal ladder filter X101, X102, X103, & X104 then a further active balanced mixer Q105, Q106, & Q107.
The VFO comprising Q114, Q115, & Q116 running the operating frequency plus IF (9.75MHz on 80m) is mixed with the output from the front end RF amplifier, the product then filtered by the four pole ladder filter providing adequate selectivity on today's busy amateur bands, before then being further mixed with the BFO this product containing the received audio.
The recovered audio is then passed through an active low pass filter R124, R125, R126, C132, C133, C134, & Q108 removing any residual RF content before being further amplified by Q109. Q110 grounds the input of the final audio amplifier during transmit, whilst Q111, Q112, & Q113 form the audio output stage of the receiver, providing upto 250mW of audio to the loudspeaker.
In transmit mode microphone audio is amplified by Q118, some tailoring of the audio response is affected here before being mixed with the BFO. The output of the first mixer being double sideband suppressed carrier, the DSB signal then passing through the four pole ladder filter to remove the unwanted sideband before being further mixed with the VFO to provide single sideband suppressed carrier at the required frequency.
The SSB signal is then filtered by T107,T108,C173,C174, & C175 forming a double tuned band pass filter impedance matched to both the balanced mixer and RF amplifier Q119, then the final RF amplifier Q120, Q121, Q122, Q123, Q124, & Q125, and finally Pi filter C183, C184, & L105 removing any residual unwanted products.
RF diode switching D109, D110, D111, & D112, move the BFO and VFO between input and output of the mixer / IF subsection, thus allowing its use for bothe transmit and receive. Diodes D113, & D114 providing antenna switching between receiver input and transmitter output
Power to receive only sections is undertaken by Q127, whilst for transmit by Q128
Voltage regulation for both the BFO and VFO is provided by Q126, D117, & D118. Generating a stable 9v supply regardless of variations in input supply.
All transistor (BC547) HF SSB TXCVR schematic:
All transistor (BC547) HF SSB TXCVR PCB layout & component placement:
All transistor (BC547) HF SSB TXCVR PCB top trace:
All transistor (BC547) HF SSB TXCVR PCB bottom trace:
All transistor (BC547) HF SSB TXCVR parts listing:
Further to the details of the pages above - the original CAD files created using EAGLE PCB Design software are included below, along with associated PDF files of both schematics and PCB layouts suitable for printing directly.
To use the original CAD files, they must be opened with EAGLE. Visit the CADsoft web site for more details, the software (including a freeware version), part libraries, tutorials, for EAGLE are available.
HF SSB TXCVR schematic A4 PDF - schematic PDF A4
HF SSB TXCVR schematic A1 PDF - schematic PDF A1
HF SSB TXCVR PCB component layout PDF - PCB component placement PDF A4
HF SSB TXCVR PCB bottom track PDF - PCB bottom track 1:1 PDF A4
HF SSB TXCVR PCB top track PDF - PCB top track 1:1 PDF A4
HF SSB TXCVR EAGLE schematic - Original CAD schematic file
HF SSB TXCVR EAGLE board - Original CAD board file
John's original details details can be found here VK3AKG The BC547 80m SSB QRP Transceiver but don't forget to check out the rest of Johns site, as there is more to come...