1W Shortwave Transmitter

While it may sound a watt insufficient to transmit radio signals , shortwave something special happen . Considering that a station as RPI ( Pirate Radio International ) , which broadcasts from the Andes ( the mast was spared the boys! ) Has a 100-watt transmitter on a J -Pole antenna type and with that power comes Russia and even China came to the conclusion that we can cover our modest quietly watt city where we mount .

1W Shortwave Transmitter Circuit Diagram

Transmitter Circuit Diagram

But we must not forget that no matter the radiated power , if our system is deficient antenna will not reach the next block . So pay attention to the type and size of antenna to use . An alternative is to build dipoles , which although large , work quite well .

Here is the electronic design of the transmitter, which we thank New Zealand station . As seen , there are a handful of passive components , two transformers , inductors and a pair of low-power transistors . The circuit is powered by 13.8vy consumes about 3 watts . In the construction of this project, take into account some aspects :
  • The temperature is crucial for the stability of the system, if the transistors overheat the output frequency can be unstable .
  • The crystal oscillator must be chosen according to the desired transmit frequency .
  • The printed circuit which will be reinforced epoxy . If using risk phenolic moisture to condense inside and make capacitance effect , altering the operation.
  • The source must be stabilized as much as possible to avoid frequency shifts .
  • The inductors should be as accurate as possible as these are calculated for optimum results.
  • If the power source is removed physically from the transmitter is advisable 100nF capacitors placed at the ends of the wire to prevent noise transmission seizes .
Once armed the system would be placed in a suitable enclosure , if metal is better. The output to the antenna is done with a conventional keg type connector . Do not use power and audio connectors . The coaxial cable to the radiant should be adequate for this type of installation. A poor wiring can reduce the final power radiated .

An out-band antenna used to increase ROE equipment, causing losses to the radiated power .

After this you need to enter the audio terminals with a modulation signal (one TDA2002 perfectly fulfills that role ) and start broadcasting in the fascinating world of Shortwave.

Remember that this type of activity is (or at least should be ) regulated by the state. Sure on the legal aspects before transmitting. According to the laws of the place where the emissions perform , we may remove the equipment and radiant . Be careful .



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