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Two Tone Generation

 

In the measurements of linearity of amplifiers and / or transmitters, a small little tool is used, its function is to generate two sinusoidal audio signals. The value of these two frequencies is not binding, what’s important is that they are both in the clear band of the transmitter filter; generally, this range is between 300 Hz and 3000 Hz for SSB emissions. Furthermore, it is appropriate that these frequencies differ between them as much as possible.

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9 MHz I.F. Module

The design and construction of the intermediate frequency amplifier dates back to 2009. As center frequency we have chosen the value of 9 MHz, and all the architecture follows the trace of the famous project CDG2000 and everything detectable online regarding this matter. I've never published anything on paper, but I am going now to publish on the Internet, believing that any good idea can also be used by other lovers of self-construction.

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Tone Oscillator

 

Oscillofono

At the Section A.R.I. Senigallia we started a course in telegraphy. Now abolished the examination requirements in proving knowledge of the CW to get the license of radio operator, the course is aimed at those who, abandoned or telegraphy after passing the exam, or who never have approached to the code Morse instead now show interest in this way of communicating.
Obviously after the retrieval of a telegraph key, it is presented the need for a tone oscillator that produces the note. After a quick search on the Internet, the first copy made consisted of an audio oscillator obtained with an integrated, NE555 in astable multivibrator configuration. Although endowed with the ability to adjust the frequency of the generated note, immediately several 'students' signaled the unpleasantness of the note. The circuit is in fact a square wave generator without any output filter, thus very far from a known 'pure'.

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Traps for 40/80 m dipole

An alternative to traps made with coaxial cable, criticized for ineffectiveness by some authors (1), is a thing from the past: a classical realization of a resonant circuit with lumped elements. Two resonant circuits, easy to reproduce and suitably robust, were made. A pipe resin, commonly used as a garden lighting support, is used to hold the inductor. The external diameter is of 60 mm and is 130 mm long. On this sleeve, 6 holes for mounting the inductor and capacitor were made.