How to specify impedances of a transistor?

[observer]

need help please

I am tring to design an amplifier with 1 W output using 2N3866 in the FM band ( 88-108) but I can not specify the impedances for the transistor , I tried to use a test circuit to measure the impedances in class C but it failed to give good results ( this methode was ok for higer power transistor and gave a good results) but for this one I coulden't even get the maximum output I burned 8 transistors till now for nothing .
The data sheet give no information about impedances .
If any one can help me or give any practical advice how to start maybe I am doing somthing wrong.


Thank u very much

 

[flatulent]

Re: need help please

One problem is using a transistor in class C if it is not designed for that class. Class C has a lot of base drive which will burn out bases. Try biasing the transistor slightly into conduction (class B) and see if you get better results.

 

[observer]

Re: need help please

Thank u Flatulent for ur advice , I'll try it

 

[Ricky761]

Re: need help please

I also used 3866 before and with a class c biasing, try to connect resitor with a value say between 10 to 22 ohms ( depends on your drive signal )
and watch out with the voltage input. First you can reduce the voltage input until you have tuned the circuit ( for the coil and capacitor adjustment ) 3866 max is 1 watt why not try a higher rating transistor like 2sc1971 ( 3 watts ) or 2sc1972 ( 10 watts ) for 12.5 volts.
can you attach your diagram so we could see how you implement the element/s in your circuit ?