4 Band Double Tuned Preselector

Circuit diagram:

Circuit Notes

The circuit requires an RF input which can be from a longwire or a loop antenna. The Preamplifier has a range from 550kHz (Medium Wave) up to 30 MHz in the SW band. The input Switch S1, applies voltage to a set of relays which switch in the appropriate coils.

The preamplifier is double tuned on the input having two IFT coils for each RF range, input applied to G1 of a double gate MOSFET. Gain control is applied to G2 and the output is taken from the DGMOSFET drain terminal. Click here for a picture of David's MW loop. Click hereto view a finished picture of this project.

Return to Radio Frequency Circuits