Thursday, July 4, 2013
Band 2 Preamplifier
This is a VHF amplifier for the Band 2 Radio Spectrum tuning approximately 88 - 108 Mhz.
Band 2 Preamplifier Circuit Diagram
Band 2 Preamplifier Circuit Diagram
Notes:
The circuit uses two 2N3819 FETs in cascode configuration. The lower FET operates in common source mode, while the upper FET, operates in common gate, realising full high frequency gain. The bottom FET is tunable allowing a peak for a particular station. Coil details follow:
The circuit uses two 2N3819 FETs in cascode configuration. The lower FET operates in common source mode, while the upper FET, operates in common gate, realising full high frequency gain. The bottom FET is tunable allowing a peak for a particular station. Coil details follow:
- L1 4 turns of 18swg air spaced with a 1cm diameter, the tap is one turn up from earth end...
- L2 4 turns of 18swg air spaced with 1 cm diameter. The coupling coil is 1 turn interwound from the supply end. Enamel coated wire must be used.
