This short-range circuit is from a publication from the 1970s. Any general-purpose PNP transistor like the BC558 can be used. The antenna is 80 cm to 120 cm and the coil is formed by two windings of 100 and 50 turns of wire 28 in a ferrite rod. The winding of 100 turns goes to the variable. The modulator transformer is an old radio transistor driver. The circuit also works with a small speaker used as a microphone.
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