How to make a transformer for RF?

hi every body
i had seen a lot of transformers that are found in RF circuits
the problem i tried to use the transformer used in power supply
but the circuit doesn't work
the question is how can i make this transformers
or how can i solve this problem

RF circuits use ferrite cores instead of steel-laminates.

You can get toroidal or rod like cores, depends on the circuit. Others like EE,EI,UI etc are easy to wind but difficult to properly close them after the winding is done, unless you are crafty. Many quality cores come with a datasheet with all the important parameters and graphs.

A LCR/Inductance Meter is invaluable when designing anything magnetic but you can also hand-compute the parameters.

All the best.

look i didn't understand u very much
but what i need exactly
if u had seen receiver of an RF circuit u will find the
first stage is an antenna with a step up RF transformer
i decided to buy a wire and round it to make the transformer
am going on the right way?

The trouble is that the RF "waves" are too small compared to the lower frequencies that the power supply transformer was designed for. You have to put the power supply transformer into a hydraulic press, and squeeze it to be smaller. Then it will work just fine!

Nice reply biff44!

mr_byte31,
Do u know basic of transformer design?
Then do u know how to use proper lamination?
how to find the turns ratio etc.

Mains transformer r for about 50/60 herts so different cores.
Rf is for khz/mhz/ghz.
Hence different cores. Also many other factors.
so don't think even of generating this type of ideas.

thanks every body for reply
here is the link for the transmitter that i need to build
http://www.web-ee.com/Schematics/TV_...VTransmitb.pdf
and like the transformers found in this link
http://www.vintage-radio.com/repair-..._vhf-sets.html
can any body help to make these transformer

I assume you are talking about T1 in TVTransmitb.pdf. It's a 4.5 MHz tuned sound IF transformer. In this project, it's used as the resonant circuit of an FM oscillator.

Have you tried buying the old transformer from the company who sells the kit? Or simply buy the whole kit?
http://www.ramseyelectronics.com/cgi...ction&key=TV6C
Assembly manual:
http://www.ramseyelectronics.com/dow...anuals/TV6.pdf

The current kit looks a little different from the old Poptronix article. The transformer's tuning capacitor may now be external to the transformer. Maybe you can buy the 42IF122 transformer from a distributor such as Mouser, and add an external 220pF tuning capacitor, just like Ramsey shows on page 9 of their new assembly manual. That's just a guess, because the schematic is missing from the manual.

thats very nice
but how can i make sure that it is the desired transformer
and if i want to wind it my self how can i know the turns ratio on the graphite rod?