Grebenkember’s original Tandem match

(Grebenkemper 1987) describes a directional coupler that has become very popular, especially in commercial implementation. The simplified circuit above from Grebenkemper’s article illustrates the key elements of the directional coupler. An important detail of the design is that the primary of the right hand transformer appears in shunt with the antenna load, and the magnetising … Continue reading Grebenkember’s original Tandem match

Coil32 inductance calculator

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

On use of enamelled wire in transmitting baluns

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

Low power Guanella 1:1 balun with low Insertion VSWR using a pair of Jaycar LF1260 suppression sleeves

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

End fed matching – analysis of VK3IL’s measurements

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