Receiver for 7MHz CW/SSB
A simple receiver with three transistors and only one coil wound on a broomstick ! The tuning is done with a copper wire shaped like a mousetrap.
The goal was to build a simple receiver , it goes without expensive components. The oscillator operates at half the reception frequency and doubled in mixer. With trimcapacitor , Ct1 , trimmed frequency to 3500kHz when the mousetrap is standing straight up . The frequency will then increase when the trap folds down over the coil. Receiver sensitivity depends on the gain after the mixer. A Darlington transistor Q2 basically consists of two interconnected transistors and represent the greatest gain. I built my Darlington from two BC550 . Q3 gives power boost to the headphones. Normal computer headphones.
The receiver is built up on a wooden plate with dimensions of 175 × 95 × 22. A sawn-off piece of a standard board that is machined on three sides. This layout is pasted on the board and blank thumbtack placed in the respective dots. Download the drawing here. And use this link to a program " viewer " to print out the drawing in scale 1:1
A little decoration around the coil gives eyecatcher .