HF Transformers

The productgroup comprises the following: SMPS transformers and Datacom/Telecom Transformers.

There are several types of transformers used in radio frequency (RF) work. (Steel laminations are not suitable for RF.)

Ferrite-core transformers
Widely used in intermediate frequency stages and in super heterodyne radio receivers, the transformers are usually canned for stability and to reduce interference.

Air-core transformers
These are used for high frequency work. The lack of a core means very low inductance. Such transformers may be nothing more than a few turns of wire soldered onto a printed circuit board.

Transmission-line transformers
For radio frequency use, transformers are sometimes made from configurations of transmission line, sometimes bifilar or coaxial cable, wound around ferrite or other types of core. This style of transformer gives an extremely wide bandwith but only a limited number of ratios (such as 1:9, 1:4 or 1:2) can be achieved with this technique.
The core material increases the inductance dramatically, thereby raising its Q factor. The cores of such transformers help improve performance at the lower frequency end of the band. RF transformers sometimes used a third coil (called a tickler winding) to inject feeedback into an earlier (detector) stage.

Baluns are transformers designed specifically to connect between balanced and unbalanced circuits. These are sometimes made from configurations of transmission line and sometimes bifilar or coaxial cable and are similar to transmission line transformers in construction and operation.

See also

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