Circuit : Andy Collinson
Email :
Modification for other Frequencies
To use the circuit at other frequencies, it is only necessary to change the values of L1 and C!. In fact if C1 is made a variable capacitor then
the circuit can be varied to operate over a particular frequency range. For convenience the turns calculator and resonant frequency are shown below. Other calculators on
my Tuned Circuit page.
For use on 80 Meters.
Change C1 to a 47pF variaable capacitor and add a parallel capacitor of 15pF
Change L1 to 40uH
To make L1 wind 63 turns of 24swg wire around a 2 cm plastic pipe and spread the turns over 3 cm.
This covers approximately 3.1 to 5.6MHz.
For use on 40 Meters.
Change C1 to a 47pF variaable capacitor and add a parallel capacitor of 33pF
Change L1 to 8uH
To make L1 wind 45 turns of 30swg wire around a 8mm plastic former such as a pen spaced about 1cm.
This covers approximately 6.9 to 9.1MHz.
Circuit Exchange International | Return to Radio Circuits | https://www.cxi1.co.uk |