400 meter radio bug

Today on the Internet you can find many schemes of radio transmitters. For many months, almost half of them were repeated, but not a single circuit showed the required parameters. Long-range schemes were encountered, but stability left much to be desired. Stable circuits, in turn, had a range of not more than 100 meters. As a result, it was decided to assemble your circuit.



Within a few days after a careful selection of radio components, a scheme for a completely new radio beetle was created. Thanks to the applied high-frequency amplifier (UHF), it was possible to increase the range of the device to 400 meters. I did the tests with the Nokia N95 mobile phone receiver, a decrease or increase in the frequency is observed, but only by 0.5 fm! The power of the radio bug is about half a watt, tests were also conducted with a double UHF, the range went over a kilometer, the LED in the antenna circuit freely lit up. Jamming of several television channels at a distance of 50 meters from the TV was also noticed. I want to note that the TV channels went down completely, only the blue screen! Let's get back to our radio transmitter.



Microwave transistors of the kt325v type were used in the transmitter and high-frequency amplifier, the cutoff frequency of these transistors is more than 1 gigahertz (1000 megahertz). The microphone took an electronic one, from a Chinese tape recorder, pick up a microphone with great sensitivity. In the photos there is a beetle layout, later it will be transferred to the board, but in smd version. The circuit contains 6 turns of wire with a diameter of 1.2 mm, wound on a frame with a diameter of 8 mm. To configure the beetle, I advise you to use the simplest pointer RF detector. With this detector, you can configure any bug in 5 minutes.



Using a variable capacitor, you can tune the transmitter to any desired frequency in the fm limit. If desired, you can increase the number of turns of the circuit to 9 - and then the transmitter will work in the range of am. My beetle caught at a frequency of 95 megahertz, although the beetle perfectly transmitted a signal in the band 94 - 96 megahertz (fm). It is convenient to use Chinese receivers, or a mobile phone receiver. Unlike other bugs, this one is excellently caught on digital technology. The range, as already mentioned, is 400 meters <>.



This range was obtained with direct visibility in the city. The microphone sensitivity is about 4 - 5 meters, the transmitter freely covers one room, even a whisper is heard. The antenna is a piece of wire with a length of 40 cm, powered by a 9-volt crown.