i got an fm tx schematic from internet the guy who drew this schematic claims that this circuit can transmit signal upto 3-4 km with a 10M Antenna! Do u guys think its true?
i got an fm tx schematic from internet the guy who drew this schematic claims that this circuit can transmit signal upto 3-4 km with a 10M Antenna! Do u guys think its true?
No, it's got two crude untuned amplifier stages, but only using puny transistors anyway (so power can only be low), I would imagine the most likely outcome is it's highly unstable.
If the output used a tuned circuit instead of the 4.7k collector resistor then its output voltage swing will be higher than the supply voltage for more output power. But its output is limited by the supply voltage so its range is limited. The antenna is a low impedance which needs more current than the weak BC549 can supply and its base current is much too low. This circuit might have a range of 500m to a very sensitive radio with nothing in between or 100m to a cheap clock radio. Across the street to a cheap TDA7000 "radio" from The Dollar Store.
The antenna for the FM band is supposed to be an 80cm whip. A 10m long antenna (but you said 10M which is extremely long) is not correct.
so should i replace the 4k7 Resistor with an inductor and trim cap? Is that what u mean with "tuned circuit"? If it is, will i get more range if added 2 or 3 more transistors?