bfr96s running hot in RF amplifier

[BigBoss]

The thing that scares me is the choice of the transistor, it costs 12-15Euros each one on ebay (inc. pp)! That is too much, I wonded if an alternative could be used.

No.. It's just 0.7 Euro each..
Also for 1uF capacitors, look at here..
https://gr.mouser.com/ProductDetail...=sGAEpiMZZMs0AnBnWHyRQFQYdTDrJniYm6x1U1wfCm4=
http://gr.mouser.com/ProductDetail/NXP-Semiconductors/BFQ18A115/?qs=sGAEpiMZZMvDjfggS9kWsYBuK9aEi8UyI62hCrMpwUQ%3d

 

[neazoi]

No.. It's just 0.7 Euro each..
Also for 1uF capacitors, look at here..
https://gr.mouser.com/ProductDetail...=sGAEpiMZZMs0AnBnWHyRQFQYdTDrJniYm6x1U1wfCm4=
http://gr.mouser.com/ProductDetail/NXP-Semiconductors/BFQ18A115/?qs=sGAEpiMZZMvDjfggS9kWsYBuK9aEi8UyI62hCrMpwUQ%3d

Thanks! I will try it when the components arrive and let you know. (It might take a few weeks).
I see that there is no base bias resistors, how is the base biased is the input signal is too low?

 

[BigBoss]

Thanks! I will try it when the components arrive and let you know. (It might take a few weeks).
I see that there is no base bias resistors, how is the base biased is the input signal is too low?

I have used ideal current source and ideal RF Choke.You should design a current source with 2-3 small signal transistor ( PTAT is preferable PTAT=Proportional To Absolute Temperature)
and Ferrite Beaded RFC. ( for instance from EPCOS ).I have given simplified principal circuit, the rest is on you..

For 100uH coil, this fits your requirements..
https://gr.mouser.com/ProductDetail...=sGAEpiMZZMv126LJFLh8y4rsEyIjbuvqfO4aSkwpCiQ=

 

[neazoi]

I have used ideal current source and ideal RF Choke.You should design a current source with 2-3 small signal transistor ( PTAT is preferable PTAT=Proportional To Absolute Temperature)
and Ferrite Beaded RFC. ( for instance from EPCOS ).I have given simplified principal circuit, the rest is on you..

For 100uH coil, this fits your requirements..
https://gr.mouser.com/ProductDetail...=sGAEpiMZZMv126LJFLh8y4rsEyIjbuvqfO4aSkwpCiQ=

I worry about the base choke and rest of the circuit. Shall I connect the current source there?
Can't I just use an ordinary voltage divider to bias the bases?