need help in rf choke

hello
i need to know how can i make rf choke for 3.5mhz
it is connected between +b and plate it function allow
the dc to flow and prevent lossing of rf signal is this right?
rf choke which i need is 2.5mh at 3.5 mhz
is there any formula for coil turns,diameter, impedance etc to make
thanks

http://www.kk5dr.com/chokes.htm

I don't know if it is too low freq. for a choke?

thanks
vfone it is useful link

fxxjssc
not low it depend on the first stage osc crystall and add rf amp and it works good
i get it through 300 turne at 1 inch air core i see the osc with scop after 300
i get the max impltude

regards