In the first part, the definition of the effective length of the receiving antenna in general was given, the relationship between the electric and magnetic fields induced by the electromagnetic wave at the receiving point was shown, and an expression was obtained for calculating the effective length of the loop antenna, consisting of one turn of the electric wire.

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How to compare the efficiency of different receiving antennas? When comparing electric receiving antennas with each other the effective length of an antenna is used as a coefficient of ratio between the voltage induced on the open-circuited terminals of the antenna and the power of the electromagnetic wave at the receiving point. And note that effective length and geometrical length of electric antennas often differ. But how to compare the efficiency of electric and magnetic receiving antennas?

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A Moscow radio amateur sent a review of the “Olusha-10” anti-noise ferrite rod antenna working. He carried out comparative testing twice and made two audio recordings that confirm the ability of this antenna to suppress radio interference in the medium wave frequency range. The comparison was carried out with the standard telescopic antenna of the “Eton E1” radio receiver, an external wire antenna about 15 m long, as well as with the loop and ferrite modules of the German active antenna “GRAHN GS5-SE”.

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Engineers and radio amateurs are interested in the static parameters of JFETs (Junction gate Field Effect Transistor), such as the zero-gate voltage drain current (IDSS) and the gate-to-source cutoff voltage (VGS(off)), as a rule, either when choosing JFET with the best parameters, or when selecting a pair of JFETs with the equal parameters for the differential stage. In this article, we will focus on the use of static parameters in the calculation of circuits based on JFETs.

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The modification of the DEGEN DE1103 radio receiver described below was done to provide the radio receiving in long and medium wave bands with an external antenna (or with the standard telescopic antenna), but not with the built-in ferrite rod antenna. Now while working on short waves too, the received signal from the standard telescopic or an external antenna is applied directly to the input of the first mixer, bypassing the Q1 transistor stage.

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Photo 1. The row of leads raised above the printed board.

Using special soldering iron tips or a hot air gun to desolder surface mount chips in a TQFP package carries the risk of overheating the chip and / or printed circuit board. Below is a method for safely removing chips in a TQFP package – without overheating and with the ability to reinstall the desoldered chip. It does not require any special soldering equipment.

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March 1, 1941 can be considered the day of the appearance of FM radio broadcasting in its usual form, that is, as a commercial industry, when the W47NV radio station with a transmitting center in Nashville, Tennessee, USA, went on the air for the first time. Here is how the American weekly “Broadcasting” wrote about this on March 10, 1941 in the article “New FM Station of WSM, in Nashville, Starts Operation With 70 Hours Weekly”:

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