Conex Club Magazine - no.7-8 - 2002

Conex Club Magazine - no.7-8 - 2002 - Irons for RF shocks and broadband transformers

Reading time: 3 minute

The main topics presented

1. Professional manufacture of printed circuits in our own laboratory - Development of exposed laminate

Development is an extremely important phase in the manufacturing flow, depending on it the final appearance of the printed wiring.

However, it is a relatively simple chemical process in which the precautions are more of a labor protection nature (rubber gloves, goggles, gown or overalls, nose / mouth mask, etc.) than of a technical nature.

2. GPS - How it works

In order for the GPS receiver to work properly, it must meet two essential requirements. The first of these is location of satellites in orbit, and the second is distance from satellite to receiver.

First let's take a look at how the receiver stores data about the location of satellites in orbit.

Remember that the receiver receives two types of information encoded from the satellite. The first type of information is called ALMANAC and it is information about how the satellites are placed in orbits and what orbits they are in at a given time.

ALMANAC is continuously transmitted by satellite and stored by the GPS receiver in memory. Any satellite can have small deviations from normal working positions at some point, so the ground stations that are part of the control segment have the task of correcting the position of the satellite in orbit, its altitude and speed.

This corrected data that the satellite receives in a coded form from the ground stations in the control segment is called EPHEMERIS.

It remains valid only for a period of time between 4 and 6 hours after which it is refreshed.

3. The noise of rain or waves

For many, the feeling of peace prior to restful sleep is induced by a repetitive background noise. Therefore, some people fall asleep more easily with the radio muted or when it is raining quietly outside.

For hot summer days, when the rain doesn't come at all and for those who can't afford a beach holiday, there is an electronic possibility to simulate (even if any copy is paler than the original) the respective sound environment.

This is the purpose of the montage presented, taken from an article written by Eng. Klaus Schlenzig and appeared in Funkamateur magazine, number 10 of 1994.

The subject is not new, several noise generators of this type appearing over time in our technical magazines. Unlike the article indicated there, it was preferred to use an audio frequency amplifier stage made with a cheap and widespread integrated circuit. (LM386N).

4. Dynamic light

Dynamic light presented is made with the AT90S1200 microcontroller and offers the user the possibility to choose one of the 16 sequences of work sequence as well as one of the 8 sequences of dynamic light.

These settings are made using one or more straps made on the pins noted in the drawing in the article with J1..J7. With the help J1..J3 choose one of the 8 work sequences and with the help of the straps J4..J7 one of those will be selected 16 times of work sequence.

The electronic control equipment is extremely simple and consists of the supply and stabilization of the 5Vdc voltage necessary to supply and operate the AT90S1200 integrated circuit.

This module uses eight LEDs to illustrate the desired work sequence.

Of course, instead of these signaling LEDs, different control equipment or a relay of the type can be used Solid State (S216SE2) to ensure the control of various user-defined devices.

5. RF shock shields and broadband transformers

The very large spread of linear broadband amplifiers, as well as the advantages of their use, is a real challenge for the amateur manufacturer. These require RF shocks and broadband transformers, both made on ferrite.

In addition, the widespread use of computers, as well as the agglomeration of the spectrum by increasing radio communications, requires increased interference protection (RFI), which requires (among other things) broadband RF shocks.

Given the practical nature of the magazine, it is presented to readers a material to support them in making these components.

6. Transceiver for 144Mhz band

In the magazine Conex Club no. 6/2001 was presented a receiver for the 2m band that uses the specialized integrated circuit MC3356. Its detailed performances are described in no. 11/2000.

Starting, in principle, from this integrated circuit, in the laboratory of Conex Electronic a transceiver was made for amateur radio users who use the 144 - 146MHz.

The main parameters of the device are:

  • supply voltage: 13.8V;
  • receiver sensitivity: better than 1uV at a signal-to-noise ratio of 10dB;
  • power at the output of the transmitter: 2.5W;

Way of working:

  • single frequency - at reception and transmission;
  • with 600kHz offset, for working using amateur radio retransmitters.


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