23cm GaAs-FET preamplifier


On 23cm the best way to obtain a good RX-sensitivity is to use a GaAs-FET in the front-end, since these devices show very low noise figures. This particular design is not very different from the common ones. I have not made any particular efforts to obtain the lowest possible noise figure or highest gain, however. A negative bias is established with a 555 and some passive components forming a voltage inverter.The current through the transistor shall be approx 15-20 mA. I had an MGF-1304 which I used, but I think it will do fine with a cheaper MGF-1302 or similar. The properties turned out to be very good compared to some references I have. Although, I have not been able to measure any gain or noise figure in exact numbers.




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