A reader of Amidon’s method of rating ferrite inductors and transformers wrote to support Amidon’s approach and cited a video by W0QE. W0QE’s video #80: High Power Balun with #31 Ferrite Material gives some measurements and simulations of a FT240-31 inductor with 11 and 14 turns. In the video he states: It turns out that … Continue reading Gauss based ferrite core loss
I have set out an initial design method for RF inductors and transformers using toroidal ferrite cores and over time I get correspondence drawing my attention to Amidon’s advice, specifically sections 1-35 and 1-36. Section 1-36 states explicitly that it is applicable to Iron Powder and Ferrite, which is interesting because they are very different … Continue reading Amidon’s method of rating ferrite inductors and transformers
A toroidal inductor is a resonator, though it can be approximated as a simple inductor at frequencies well below its self resonant frequency (SRF). Lets take a simple example, a ferrite toroid of rectangular cross section. From the basic definition we can derive the relationship that the flux density in the core with current I … Continue reading Calculation of impedance of a ferrite toroidal inductor – from first principles
At nanoVNA-H – measure ferrite transformer I gave an example of using a nanovna to measure loss of a ferrite cored transformer. Noelec makes a small transformer, the Balun One Nine, pictured above and they offer a set of |s11| and |s12| curves in a back to back test. (Note: back to back tests are … Continue reading nanoVNA-H – measure ferrite transformer – Noelec balun
This article demonstrates the use of the (modified) nanoVNA-H to measure Loss (Transmission Loss) and Insertion Loss of a small ferrite 64:1 RF transformer, and the Insertion VSWR and Return Loss. The transformer was designed for a receive application at 9MHz. Firstly let’s define the meaning of the terms: Last update: 2nd February, 2020, 7:11 … Continue reading nanoVNA-H – measure ferrite transformer
This article demonstrates the use of the (modified) nanoVNA-H to capture data from which the complex relative permeability of an unknown ferrite core is calculated and plotted Above, a single turn of wire through the sleeve allows measurement by the nanovna. The nanoVNA fundamentally captures s11 parameters which we need to convert to relative permeability. … Continue reading nanoVNA-H – measure ferrite core permeability
One often sees experts online insisting that s11 reflection impedance measurements of common mode chokes is inaccurate, and the ONLY way is s21 series measurement. This one is built upside down so the connections are visible. In this experiment using the SDR-KITS VNWA testboard (above), a series of measurements are made of an inductor, and … Continue reading nanoVNA-H – a ferrite cored test inductor impedance measurement – s21 series vs s11 reflection
The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50. This article documents some tests using a small ferrite cored test inductor that provides a similar impedance to that of a common mode choke suited to HF antenna feed lines. The nanoVNA-H has firmware NanoVNA-Q-0.4.3-20f33ba.dfu installed. … Continue reading nanoVNA-H – a ferrite cored test inductor – drilling down on a glitch – the fix
The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50. I have been evaluating one for common tasks around a ham station and noticed a persistent glitch around 7.5MHz in scenarios where |s21| is high. The nanoVNA-H has firmware NanoVNA-Q-0.4.3-20f33ba.dfu installed. The nanoVNA appears to be … Continue reading nanoVNA-H – a ferrite cored test inductor – drilling down on a glitch
The NanoVNA is a new low cost community developed VNA with assembled units coming out of China for <$50. This article documents some tests using a small ferrite cored test inductor that provides a similar impedance to that of a common mode choke suited to HF antenna feed lines. The nanoVNA-H has firmware NanoVNA-H_20191018.dfu installed. … Continue reading nanoVNA-H – a ferrite cored test inductor