Tunable RF coils question

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Some Oriental S8050 transistors are NPN and others are PNP. I think the translation messes it up.
It has the same max heat dissipation of 625mW (not 1W) as nearly every other little transistor in a TO-92 case.

But in your circuit the 100 ohm emitter resistor limits the average current to only 28mA so the heating is not much and the output power is very low.
 
so should i change the 100ohm to a smaller value to get more range?(2km is morethan enough for me tho)
 
Ziddik said:
so should i change the 100ohm to a smaller value to get more range?(2km is morethan enough for me tho)
Click to expand...
Reducing the emitter resistor value will try to cause increased current but the simulations I posted show that the transistor is badly clipping because the current is already as high as it can go.
If you increase the supply voltage then the range will be more.

https://pcs-electronics.com/schematic...orDatabase.htm says 1w(search for s8050 in that page for ease)
Click to expand...
The list is wrong for the very common American 2N3904 and 2N3906 so maybe it is also wrong for the S8050.
 

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it's true, The oscillator stops when the RF amplifier is cap-coupled to its collector, so i will try to connect to emitter, but the rf amplifier gets hot when i power it with 9V, why is that? Maybe i need a resistor in the emitter pin?
 
Last edited:
Ziddik said:
it's true, The oscillator stops when the RF amplifier is cap-coupled to its collector, so i will try to connect to emitter, but the rf amplifier gets hot when i power it with 9V, why is that? Maybe i need a resistor in the emitter pin?
Click to expand...
My FM transmitter is almost the same circuit as yours in post #17 and its RF amplifier transistor gets warm, not hot.
 
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