80m SSB & CW QRP superhet transceiver




RF "base"

SSB & CW modulator

Headphones amp.



VFO & BFO, 600dpi gif (118kB)

Main board, 600dpi gif (295kB)


VFO & BFO, 600dpi gif (73kB)

Main board, 600dpi gif (204kB)


Inside view - top

Inside view - bottom


The 80m SSB & CW transceiver design is based on an already proven concept used in ATLAS amateur transistorised transceivers from 70's. The "two-mixer + 1 XTAL filter" design uses the 1st mixer as front-end mixer on receive as well as SSB modulator on transmit. The second mixer is used as SSB product detector on receive and as a heterodyne mixer on transmit. VFO and BFO are cross-switched between both mixers with a PIN diode matrix. Between 1st mixer's output and 2nd mixer's input a crystal filter is placed, followed by an AGC PIN attenuator. AF/RF passive splitter (combiner) takes care about the proper separation of AF and RF signals at the 2nd mixer's output as well as combining them at the 1st mixer's input. The antenna switching between receiver and transceiver is done by a single 1N4007 diode. No relays are used in the transceiver. 

Both implemented mixers are AD831 type, XTAL filter is made of six 6,400 MHz crystal units and has approx. 2,7kHz of bandwidth.

There is no SSB/CW mode switch. With the activated PTT button you are "on-air" in phone mode, if you push the KEY, you are "on-air" CW. CW mode has priority over SSB mode. CW can be operated in either LSB or USB.

With the exception of both oscillators, diode switching matrix and TX PA, all transceiver units are placed on one main PCBoard. The on-board audio output stage is capable of driving low-impedance stereo headphones. There is separate BFO / VFO PCB which also includes the diode switching matrix. Unlike other my transceiver designs this one is built mostly using classical (wired) components. SMT components are used only around both mixers, mainly because I didn't want any unpleasant surprises, since the mixers are UHF units. I added to the transceiver a LM380 based AF amplifier, built on separate prototype board. Transmitter PA is constructed by using an effective technique described by 7N3WVM. I slightly adapted this "fast home-brewing" method by using a double-sided board, which is not the case with the original 7N3WVM suggestion, if I understand it right. The PCB layouts are not shown on this site.


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