I am used to transformers working at lower frequencies like 60 Hz. Recently I am faced with a problem of having to step up the voltage at 20MHz by a factor of about 5. I thought I could build a transformer using a T30 - 10 toroid. I played around with turns a couple of times but couldn't get any indication of step up around 20MHz. Infact the voltage got attenuated more as I increased the drive frequency. I reduced the overall turns hoping to reduce the overall inductance and gain-bandwidth but that didn't help.

I would like to know what are the basic things to consider when building transformer around those frequencies. suggestions of tutorials, books and articles will be appreciated as well as suggestions on some commercial RF transformers that I can buy.

Thanks

 

The impedance of the windings needs to match the source and load. There is a handy calculator for this toroid here:
http://toroids.info/T30-10.php

 

Thanks AlbertHall, I will have a look at the calculator and consider your advice on impedance matching.