Archive for April, 2008
Simple mixer circuit schematic - Common base
The mixer schematic is build on common base principle, where input voltages are transformed in alternative currents wich are summed to form the alternative current component for the collector. The total amplification is R6 / Ri, where Ri is one of the input resistors. I’ve build this mixer for a little transmitter and works great.
Radio field indicator with MOS-FET
A rf field indicator is required to verify power stages and transmitters antennas. With this radio field indicator you can measure radiated energy from antenna. This circuit is very sensitive, a weak signal is enough.
The S2 commutator allows to select : 480KHz … 2.4MHz / 2.4MHz … 12MHz / 12MHz … 40MHz.
A 30cm long wire [...]
VN66AF 27MHz CB amplifier
The 10 meters 27MHz CW radio amplifier is equiped with VN66AF transistor produced by Siliconix wich has some advantages: its cheap, great dielectric insulation and high gain. Here we use VN66AF as an rf amplifier for 10m band (26 … 30 MHz ).
With this 27MHz rf amplifier, small transmitters ~ 200mW, can be transformed in [...]
