Method for manufacturing chokes for TX. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Method for manufacturing chokes for TX. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Nodes of amateur radio equipment

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The inductor for the output stage of a parallel-powered transmitter is a very important part that can cause a number of unpleasant phenomena, from self-excitation to spontaneous combustion.

Traditionally manufactured multi-band choke is the optimal quarter-wave line for the lowest frequency range. Half-wave resonance frequencies for other, shorter wavelength bands are often located near the operating frequencies of the transmitter, which leads to trouble.

Using a ferrite core with a sufficient initial magnetic permeability, it seems possible to make a choke, in which the first half-wave resonance will be located outside the amateur radio bands.

So, the inductor is wound on a ferrite rod with a permeability of 600 ... 800, a diameter of 8 mm, a length of 72 ... 75 mm. Wire 0,45 PEV-2. The winding is 40 mm long, continuous, 25 mm - progressively in increments of 0,5 to 4 mm (about 15 turns). Only 95 turns. The choke has the first half-wave resonance at a frequency of 32 MHz. The inductance at 1 MHz is 300 mH. Thus, quite acceptable parameters are provided in the range from 1,5 to 30 MHz without resonances.

Author: O.Puzanov (UB5LW); Publication: N. Bolshakov, rf.atnn.ru

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