From: Starz and Stripes on Jul 2, 8:50 pm


How do you measure the impedance of a broadband transformer for a RF
transistor amplifier? I'm referring to the input and output broadband
tranformers just before and after the transistor finals.

With a broadband network analyzer and a set of resistive
terminations...over a wide bandwidth of frequencies. To be
very precise. But, you don't have to be that precise.

It's no different than checking an old audio transformer, such as
a vacuum tube output amplifier's transformer. Just count the
turns in each, square the ratio of the number of turns, and
you have the "impedance ratio." That's a rough approximation
which usually works well for most things.

All the answers depend on what you want to find out about this
solid-state RF amplifier. Please give more details on desires.

Most of the Motorola App-Note designs are detailed enough to
get the data direct, including designing your own particular
broadband transformer thingy. Helge Granberg did a nice job
very detailed in those App Notes.