A recent online posting gave unequivocal recommendation for the Coil32 Inductance Calculator for application to a ferrite toroidal HF current balun. Always interested in these things, I tried to download it to evaluate it but there was rigmorol to create an account and aware that I have never downloaded a calculator that handled that specific … Continue reading Coil32 inductance calculator
An online poster recently sought to design a broadband 9:1 transformer for HF. Choosing a BN43-2402 balun core, he planned to use a 2t primary and 6t secondary for a nominal 50Ω input. He subsequently posted measurements of the prototype. What might we expect… is it a good starting point. A first approximation at the … Continue reading BN43-2402 balun example
The OCF short vertical dipole for HF has become popular, particularly disguised as a flag pole for low impact installations and encouraged by claims of outstanding performance. The antenna was described in QST and a commercial version was available at time of writing. The rationale for the design is that it is a short dipole, … Continue reading OCF short vertical dipole for HF
I saw a recent discussion where the blind were leading the blind on the dimensions of a twisted two wire line for Zo=50Ω for use in a balun. The poster had used an online calculator which used the well known log function for estimating Zo of an air spaced two wire line… the calculator, like … Continue reading Zo of two wire line
The Red Dot 2016A is a digital HF+ VSWR meter. The frequency range is specified as 1.6-60MHz. Last update: 25th July, 2016, 1:10 PM
I have published a number of transmitting balun designs, and none of them use enameled wire. I am sometimes asked why is that so, but more often advised that it is a better solution than the wires that I have used. enameled wire depends on an insulating coating, and its breakdown voltage depends on the … Continue reading On use of enameled wire in transmitting baluns
The article describes a current balun with low Insertion VSWR for operation at modest power levels. It is lightweight and well suited to portable operations, and can be made with materials readily available in Australia (LF1260 cores are a little over $1 each in packs of six.) Last update: 7th May, 2017, 10:45 AM
David, VK3IL posted EFHW matching unit in which he describes a ferrite cored transformer matching unit that is of a common / popular style. Above is David’s pic of his implementation. It is a FT140-43 toroid with 3 and 24t windings and note the 150pF capacitor in shunt with the coax connector. The popular belief … Continue reading End fed matching – analysis of VK3IL’s measurements
The article describes a current balun intended for use with an ATU at modest power levels. It is lightweight and well suited to portable operations, and can be made with materials readily available in Australia (LF1260 cores are a little over $1 each in packs of six.) Last update: 15th March, 2016, 10:49 AM
A correspondent having read End fed matching – design review raised a similar design by PA3HHO which uses a#43 ferrite toroid as part of an end-fed matcher, see Multi band end-fed (English). Further to End fed matching – PA3HHO design review , this article has a solution to PA3HHO’s “original 40/20/10 version” using FT140-43 with … Continue reading End fed matching – PA3HHO design review #2