Search Results for: ferrite

A method for design of small broadband RF transformers using medium µ ferrite core for receiving use

A simplified design for small broadband RF transformers using medium µ ferrite core for receiving use. The characteristic of typical medium µ ferrite mixes, particularly NiZn, are well suited to this application. This article continues with the design discussed at BN43-2402 balun example, but using a 4t primary and 12t secondary for a nominal 1:9 … Continue reading A method for design of small broadband RF transformers using medium µ ferrite core for receiving use

Some tools for designing a Guanella 1:1 balun using ferrite toroids

In designing a Guanella 1:1 balun, selecting a ferrite core that has been characterised by the manufacturer simplifies the design process greatly. The manufacturer’s full characterisation includes curves for complex permeability vs frequency and from these the magnetising impedance of the core can be calculated. Note though that tolerances on magnetics are usually fairly wide … Continue reading Some tools for designing a Guanella 1:1 balun using ferrite toroids

Designing a Guanella 1:1 balun using the ‘unknown’ ferrite toroid

At Characterising an unknown ferrite toroid an ‘unknown’ ferrite toroid was characterised. This article uses that information for design of a Guanella 1:1 current balun. The proposed design uses 11t of small coax wound in the Reisert ‘cross-over’ style. The impedance of a single turn vs freq was used to predict the impedance of an … Continue reading Designing a Guanella 1:1 balun using the ‘unknown’ ferrite toroid

Characterising an unknown ferrite toroid

The ‘unknown’ toroid is wound with a single turn and measured with a VNA, an AIMuhf in this case. Of interest in the first instance is the apparent inductance of the single turn winding at low frequencies where typically permeability µ is fairly constant and core loss is fairly low. Last update: 26th December, 2015, … Continue reading Characterising an unknown ferrite toroid

Accuracy of AIMuhf system – AIM910A vs several recent versions on a ferrite cored inductor

Yet another release of AIM software is available, 910A at the time of writing. I have downloaded and tested 8 versions this year, most have been wanting. Again, there is very little detail on what has changed and likely impact on historical measurments. A quick set of measurements was made on my test inductor pictured … Continue reading Accuracy of AIMuhf system – AIM910A vs several recent versions on a ferrite cored inductor

Thermal observations on Neosid 28-053-31 ferrite toroid

The Neosid 28-053-31 ferrite toroid is used in my HF Balun Project. This article reports some thermal measurements and analysis made in relation to the project some years ago, but possibly of interest. Above is the Neosid 28-053-31 ferrite toroid in an implementation of my HF Balun Project using XLPE wire for the winding. The … Continue reading Thermal observations on Neosid 28-053-31 ferrite toroid

Interpreting temperature rise in ferrite cored RF transformers and inductors

  We often see statements by hams where they draw inference from observed temperature rise of a ferrite core at RF. Lets consider the following statement. The FT-240-43 balun MUST be quite efficient as it barely increased in temperature over a 5 minute over at 100W on SSB. For the purpose of this explanation, lets … Continue reading Interpreting temperature rise in ferrite cored RF transformers and inductors