Project
20/80m CW QRP Transceiver
November 2018, DL6ZB


This a 20/80m imaging CW QRP transceiver. The output power is about 1.5 watts into a 50 ohm load. Design goal was to make it simple with parts from the junk box. Here's the final design. The receiver is a single conversion with an IF of 9 MHz. A junk box 2,7 kHz KVG XF9B crystal filter was used here. It isn't very selective for CW use. Therefore I added a simple OpAmp AF filter. A small speaker or a high impedance headphone may be used. The VFO is 5.0-5.5 MHz. Mixed with the 9 MHz IF this results in 14.0-14.5 MHz and 4.0-3.5 MHz imaging transceiver. Some of the ideas are from VA3IUL and W7EL.

Click on schematic to get a high resolution version.

Schematic


Front View.

Front


Top view.
- VFO with a 1:36 planetary gear
- IF and AGC amplifier (open case)
- S-Meter
- Crystal Filter
- AF amplifier

Top


Bottom view.
- Front Plate
- RF TX pre and power amplifiers
- AF pre-amplifier and AF filter
- 9 MHz RX&TX crystal oscillators
- Bandpass and TX low pass filters
- T/R switching

Bottom