ANTENTOP- 01- 2014 # 018

Simple AM Tube Transmitter for 1.5- 3.5- MHz

By Georgiy Gorelashvili , 4L1G

4L1G

The schematic (in different variations) was very popular in ex-USSR. There is possible use any powerful pentode with tap from the third grid (for modulation). Of course, frequency of the transmitter is not stable but it is quite possible use for experimental purposes.

Parts List:

Microphone: Carbon microphone from old telephone set.

Transformer: Best choice is to use a special transformer from surplus military radio. Transformer is hard to make because the second winding contains 6000 turns of wire 0.08- mm (39- AWG). However, an audio transformer from an old tube radio receiver would work fine.

Bulb at antenna circuit: 3.5v- 0.15... 0.5-A. Amperage depends on antenna impedance.

L1: 10 turns, wire 1.2- mm (AWG-16), diameter 35-mm.

L2: 25 turns, wire 1.2-mm (AWG-16),

diameter 30-mm.

L3: 30-turns, wire 0.5-mm (AWG-24)

Tap from 25s and 10s turn. Diameter 25-mm

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