tuned circuit for FSK LNA amplifier

[a3abdelhafez]

hi for all

i make LNA at range between 45&49MHZ for FSK receiver

i want to make two tuned circuits at input of LNA for desired frequncies

the qustion now can i find coil in this range with high quality factor?

 

[xxargs]

hi for all

i make LNA at range between 45&49MHZ for FSK receiver

i want to make two tuned circuits at input of LNA for desired frequncies

the qustion now can i find coil in this range with high quality factor?

Selfmade coil in most case.. you can incrase Q-value if you winding with flat copper strip from copper sheet compare to circular copper wire. - circular geometry is best shape to make most possibly skin-effect... flat shape or Litz-wire give lot lower skin effect compare to massive circular wire.

with circular massive copper wire you can make around Q = 200 , possible 300 in best case , but with flat copper strip I succesfully make near Q=450 in my try to make band reject filters in 70 MHz range (reject deep is _very_ depend of Q-value... and one of methodes to measure Q-value).

 

[ahmad_abdulghany]

How can I make that flat copper coil? do you mean copper on board??

Thanks in advance,
Ahmad,

 

[xxargs]

How can I make that flat copper coil? do you mean copper on board??

Thanks in advance,
Ahmad,

simular

I use buyed copper-sheet around 0.1 - 0.2 mm thickness (Im in vacation, cannot check thickness on my work just now)

copper on FR4-board is litte for thin and more or less hydrogenium hardened (from plastic/glue over long time and/or electroplating process, its not same 'plastic' as copper wire/sheet or new glown small copper oil-pipe) and often brittle and easy to broken/cut itself in very hard bend (for example moment to draw off from FR4-board).

but, you can try, easiest way is using hot air-fan to soften glue between board and copper sheet and start lift copper from corner.

 

[ahmad_abdulghany]

Thank you xxargs,
But, sorry, i'm still unable to imagine the process you described above, can you give simple illustration drawing for the process of that coil!?

Thanks alot..
ahmad,