The answer to these questions depends entirely on what you are trying to do. The answers you seek are not unique. Again a schematic would be helpful.

here is the schematic,there u can see the F1 and F2,the designer says the parameters for the both are : F1 = F2 = 18turns/0.5mm/2.5mm/ferite.
so if we calculate the inductance ,the result will be 30nH.so tell me can i use a solenoid air-core inductor with a value of 30nH,instead of ferrite core.will there be any major problem or please give me any advise!

 

At VHF frequencies of 50-150MHz. the physical size of your inductors will be important. If the air core inductor is not more than 50% larger thna the ferite core you may have a fighting chance. The parasitic interwinding capacitance may also affect the match on the input and output of T1. The real problem is if you build it and it doesn't work how will you ever find out what is wrong and how to fix it.

It looks like a risky propsition.

 

please help me in making thos RF chokes.pleaseeee pleaseeee

 

can a HF RF power amplifier be made with using RF chokes without Ferrite core, or without a ferrite core cant we make RF amplifier at all!please advice me

 

Do you have an Oscilloscope, or at least an LCR Meter?

If not, stating the number of turns on xx diameter form will only get you sort of close, and when it doesn't work, there isn't anything we would be able to do to assist.

There are a large amount of details to consider, and measure when things aren't working correctly. The only way to measure the circuit is with a scope.

 

why is ferrite core used in RF chokes!i think to reduce the size of the RF choke,for example. a 1mH RF choke with ferrite core will be smaller than the 1mH air core rf choke.am i right!

 

You might find the following article helpful
http://powerelectronics.com/mag/power_inductor_core_material/