Search Results for: efhw

A simple Simsmith model for exploration of a common EFHW transformer design – 2t:14t

This article describes a Simsmith model for an EFHW transformer using a popular design as an example. This article models the transformer on a nominal load, being . Real EFHW antennas operated at their fundamental resonance and harmonics are not that simple, so keep in mind that this level of design is but a pre-cursor … Continue reading A simple Simsmith model for exploration of a common EFHW transformer design – 2t:14t

A simple Simsmith model for exploration of a common EFHW transformer design – 2t:16t

This article describes a Simsmith model for an EFHW transformer using a popular design as an example. This article models the transformer on a nominal load, being . Real EFHW antennas operated at their fundamental resonance and harmonics are not that simple, so keep in mind that this level of design is but a pre-cursor … Continue reading A simple Simsmith model for exploration of a common EFHW transformer design – 2t:16t

Shorting winding sections of a ferrite cored EFHW transformer

A chap recently posted some advice on construction of a dual ratio transformer for EFFHW antennas, advice with an informative pic, but without measurement evidence that it works well. Pictured is a dual UnUn. I made this for experimenting. It’s both a 49 and 64 to 1 UnUn. The 49 to 1 tap uses the … Continue reading Shorting winding sections of a ferrite cored EFHW transformer

Small efficient matching transformer for an EFHW – a Simsmith model

This article offers a simple Simsmith model for the Small efficient matching transformer for an EFHW. Above is the model topology. D1 is a daemon block which essentially, calculates key values for the other blocks based on exposed parameters and the named ferrite material complex permeability data file. The prototype used a Fair-rite 2643625002 (#43) … Continue reading Small efficient matching transformer for an EFHW – a Simsmith model

A Smith chart view of EFHW transformer compensation

I have written several articles on design of high ratio ferrite cored transformers for EFHW antennas. Having selected a candidate core, the main questions need to be answered: how many turns are sufficient for acceptable InsertionVSWR at low frequencies and core loss; and what value of shunt capacitance best compensates the effect of leakage inductance … Continue reading A Smith chart view of EFHW transformer compensation

FT240-43 matching transformer for an EFHW – NEC model at 3.6MHz

The article End Fed Half Wave matching transformer – 80-20m laid out a design for a EFHW transformer based on the readily available FT240-43. This article builds an NEC model for an EFHW antenna at 3.6MHz incorporating a realistic model of the above transformer. NEC provides for a NT card characterising a two port network … Continue reading FT240-43 matching transformer for an EFHW – NEC model at 3.6MHz

Small efficient matching transformer for an EFHW – NEC model at 3.6MHz

The article Small efficient matching transformer for an EFHW laid out a design for a small EFHW transformer. This article builds an NEC model for an EFHW antenna at 3.6MHz incorporating a realistic model of the above transformer. NEC provides for a NT card characterising a two port network using Y parameters. Y parameter model … Continue reading Small efficient matching transformer for an EFHW – NEC model at 3.6MHz

EFHW exploration – Part 2: practical examples of EFHW

EFHW exploration – Part 1: basic EFHW explored the basic half wave dipole driven by an integral source as a means of understanding that component of a bigger antenna system. The EFHW can be deployed in a miriad of topologies, this article goes on to explore three popular practical means of feeding such a dipole. … Continue reading EFHW exploration – Part 2: practical examples of EFHW