I saw a recent discussion where the blind were leading the blind on the dimensions of a twisted two wire line for Z0=50Ω for use in a balun. The poster had used an online calculator which used the well known log function for estimating Z0 of an air spaced two wire line… the calculator, like … Continue reading Z0 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 enamelled 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. enamelled wire depends on an insulating coating, and its breakdown voltage depends on the … Continue reading On use of enamelled 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
A correspondent wrote with concern of the apparent difference between graphs produced by my #52 choke design tool with a graph published by G3TXQ of his measurement of 11t on a pair of stacked FT240-52 cores. I published a note earlier about my concerns with a similar graph by G3TXQ compared to the Fairrite datasheet, … Continue reading Reconciling my #52 choke design tool with G3TXQ’s measurements
The article describes a current balun intended for measurement use with low power instrumentation. It is lightweight and can be made with materials readily available in Australia (LF1260 cores are a little over $1 each in packs of six). The target application is for a 600mm square small loop for field strength measurement below 15MHz. … Continue reading Low Insertion VSWR HF Guanella 1:1 balun for instrumentation
Measuring an RF inductor This article walks through practical measurement of a ferrite toroidal inductor using an antenna analyser. To be relevant practically, lets use an example from N4SPP’s end fed wire antenna on 3.6MHz. His coupling transformer uses a two turn winding on an FT240-43 core for the nominal 50Ω connection to the antenna … Continue reading Exploiting your antenna analyser #10