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

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

WW1WW’s matching transformer for an EFHW

At PD7MAA’s BN43-202 matching transformer for an EFHW I gave an estimate of the core loss in PD7MAA’s transformer. An online expert questioned the analysis and later measurements, and proposed his own transformer design as evidence. Notably, his transformer uses #61 material and a larger binocular core, a Fair-rite 2861006802 with 2t for a nominal … Continue reading WW1WW’s matching transformer for an EFHW

Small efficient matching transformer for an EFHW

At FT82-43 matching transformer for an EFHW I wrote about the likely losses at 3.6MHz of a common design using a FT82-43 ferrite core with a 3t primary. In that case, expected efficiency (meaning PowerOut/PowerIn) of the transformer was less than 65% at 3.6MHz. I have been offered input VSWR curves for such a configuration, … Continue reading Small efficient matching transformer for an EFHW

FT82-43 matching transformer for an EFHW

A published design for an EFHW matching device from 80-10m uses the following circuit. Like almost all such ‘designs’, they are published without supporting measurements or simulations. The transformer is intended to be used with a load such that the input impedance Zin is approximately 50+j0Ω, Gin=0.02S. Analysis of a simple model of the transformer … Continue reading FT82-43 matching transformer for an EFHW

On winding configuration of EFHW matching transformers

The net abounds with articles on broadband transformers (ie untuned) for matching End Fed Half Wave (EFHW) antennas to 50Ω. One of the aspects that is common to most designs is that the turns of the primary winding are wound ‘bifilar’ with the start of the secondary winding, indeed the twist pitch is often very … Continue reading On winding configuration of EFHW matching transformers

Ellington 3 x FT240-52 matching transformer for an EFHW

Ellington describes in a Youtube video his high power matching transformer for an EFHW, he rates it suited to 500W CW. Like almost all such ‘designs’, they are published without supporting measurements or simulations. The transformer is intended to be used with a load such that the input impedance Zin is approximately 50+j0Ω, Gin=0.02S. Analysis … Continue reading Ellington 3 x FT240-52 matching transformer for an EFHW

PD7MAA’s BN43-202 matching transformer for an EFHW – full measurement set

I have written some recent articles about or relevant to PD7MAA’s BN43-202 EFHW matching transformer. At about the same time a discussion started on and through that discussion, one ‘online extra expert’ stated that my analysis was bogus (dictionary meaning: not genuine, faked, a misrepresentation). This article presents detail that was not included in the … Continue reading PD7MAA’s BN43-202 matching transformer for an EFHW – full measurement set