Search Results for: ferrite

Low power Guanella 1:1 balun with low Insertion VSWR using a Fair-rite 2843009902 binocular – design workup

The article Low power Guanella 1:1 balun with low Insertion VSWR using a pair of Jaycar LF1260 suppression sleeves describes a current balun with low Insertion VSWR for operation at modest power levels. The design was based on Jaycar LF1260 cores which are readily available in Australia. This article presents the workup of a balun with … Continue reading Low power Guanella 1:1 balun with low Insertion VSWR using a Fair-rite 2843009902 binocular – design workup

Low power Guanella 1:1 balun with low Insertion VSWR using a pair of Fair-rite 2631540002 suppression sleeves – design workup

The article Low power Guanella 1:1 balun with low Insertion VSWR using a pair of Jaycar LF1260 suppression sleeves describes a current balun with low Insertion VSWR for operation at modest power levels. The design was based on Jaycar LF1260 cores which are readily available in Australia. This article presents the workup of a balun with … Continue reading Low power Guanella 1:1 balun with low Insertion VSWR using a pair of Fair-rite 2631540002 suppression sleeves – design workup

A magnetics review of the VK3AMP Sontheimer directional coupler

This article documents a review of the magnetics of the ‘voltage’ transformer in the VK3AMP Sontheimer directional coupler. It is typically the most important component in determining InsertionVSWR and ReturnLoss at the lowest frequencies. The transformer of interest is the one to the left, and if you follow the tracks, the multiturn winding is connected … Continue reading A magnetics review of the VK3AMP Sontheimer directional coupler

Basic measurements of the VK3AMP Sontheimer directional coupler for a N2PK wattmeter

This article documents measurement and analysis of a VK3AMP Sontheimer directional coupler in an implementation of a 400W wattmeter design by N2PK (Kiciack nd). I purchased one of the couplers for use with a DIY digital display, and although I have had it longer, it isn’t yet realised! A common failing of almost all hammy … Continue reading Basic measurements of the VK3AMP Sontheimer directional coupler for a N2PK wattmeter

Fair-rite’s ‘new’ #43 permeability data (2020)

Fair-rite publishes spreadsheets of the complex permeability characteristic of many of the ferrite mixes. This note is about #43 mix and clarification I sought from Fair-rite. Question I note that recently, the published table of #43 permeability changed subtly but significantly. Does this table apply to historical product, or does it only apply to new … Continue reading Fair-rite’s ‘new’ #43 permeability data (2020)

Improving ‘s21 series-through’ measurement of high impedances – more detail

Improving ‘s21 series-through’ measurement of high impedances canvassed a possible improvement of the s21 series-through measurement of impedance to compensate for errors in VNA port impedances that are not corrected in simpler calibration / correction schemes. This article provides more detail on the practical test case. A small ferrite cored test inductor was measured with … Continue reading Improving ‘s21 series-through’ measurement of high impedances – more detail

Improving ‘s21 series-through’ measurement of high impedances

This article canvasses a possible improvement of the s21 series-through measurement of impedance to compensate for errors in VNA port impedances that are not corrected in simpler calibration / correction schemes. The diagram above is from (Agilent 2009) and illustrates the configuration of a series-through impedance measurement. Last update: 21st April, 2023, 9:54 AM

Using complex permeability to design with Fair-rite suppression products

Fair-rite allocates some of its closed loop ferrite products to two different categories: inductive; and suppression. Sometimes the same dimensioned cores are available in both categories with different part numbers and possibly different prices, implying some real difference in behavior, eg 5943003801 and 2643803802 are both FT240-43 sized cores. Material datasheets often contain a note … Continue reading Using complex permeability to design with Fair-rite suppression products

The j value

I have noticed growing use of new lingo for reactance on hammy online forums… the term j value is replacing Reactance in the ham vernacular (though of course j does not distinguish Reactance from Susceptance). A well-designed ferrite transformer operated in the HF spectrum is close to ideal, so if it steps R by 2, … Continue reading The j value

nanoVNA – evaluation of a voltage balun – RAK BL-50A

In this article, I will outline an evaluation of a ‘classic’ voltage balun, the 1:1 RAK BL-50A voltage balun, specified for 1.8-30MHz. These were very popular at one time, but good voltage baluns achieve good current balance ONLY on very symmetric loads and so are not well suited to most wire antennas. Above is a … Continue reading nanoVNA – evaluation of a voltage balun – RAK BL-50A