This is a no-frills homebrew direct conversion receiver that is capable of receiving local and overseas stations on the popular 14 MHz band.
It is based on an 80 metre design by Drew Diamond VK3XU, but modified for 20 metres. The well-known NE-602 is used as the product detector. A MPF102 RF amplifier assures adequate sensitivity. The audio stage uses the common 741/386 combination, though connoisseurs may wish to substitute a lower noise op-amp for the 741.
Component values provide high and low frequency roll-off suitable for SSB. For better CW reception, increase the 4700pF capacitor between pin 2 and 6 of the 741 to 0.047uF, the 4700pF off Pin 3 to 0.022uF and reduce the 1uF near the AF Gain control to 0.1uF.
Build the VFO in a separate box, use solid construction and quality components for best stability. A vernier dial drive makes tuning easier. Battery operation is preferred to reduce the risk of hum.
The set is ideal for portable use because of its low power consumption. It can also be teamed up with a CW or DSB transmitter to make a transceiver.
Click here for the schematic diagram for this project
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This page was produced by Peter Parker VK3YE (parkerp@alphalink.com.au). The page is continually under construction. Material may be copied for personal or non-profit use only.
