The actual preamplifier in this circuit is a practical wideband amplfier that gives about 15 - 20dB of gain from 1.8 MHz through to well over 200 MHz. You will no-doubt replace this circuit for your own favorite amplifier for the band you are interested in.
The 2.2mH chokes should have an absolute minimum reactance of 5000 ohms at the lowest frequency to be used. For 145 MHz these may simply consist of a few turns of wire. I personally used a 10-turn 4mm Dia. coil in series with a 2.2mH torroidal inductor.
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